.net core

Continuous Deployment of Cloud Services with VSTS

October 18, 2017 Coding 4 comments , , ,

Continuous Deployment of Cloud Services with VSTS

In my last blog post, I showed how you can use ASP.NET Core with an Azure Cloud Service Web Role. The next step is to enable CI/CD for it, since you really shouldn’t be using “Publish” within Visual Studio for deployment.

As part of this, I wanted to configure the Cloud Service settings per environment in VSTS and not have any configuration checked-in to source control. Cloud Services’ configuration mechanism makes this a bit challenging due to the way it stores configuration, but with a few extra steps, it’s possible to make it work.

What you’ll need

To follow along, you’ll need the following:

  • Cloud Service the code can live in GitHub, VSTS, or many other locations. VSTS can build from any of them.
  • Azure Key Vault we’ll use Azure Key Vault to store the secrets. Creating a Key Vault is easy and the standard tier will work.
  • VSTS this guide is using Visual Studio Team Services, so you’ll need an account there. Those are free for up to five users and any number of users with MSDN licenses.

What we’re going to do

The gist here is that we’ll create a build definition that publishes the output of the Cloud Service project as an artifact. Then, we’ll create a release management process that takes the output of the build and deploys it to the cloud service in Azure. To handle the configuration, we’ll tokenize the checked-in configuration, then use a release management task to read configuration values stored in Key Vault and replace the matching tokenized values before the Azure deployment.

Moving the configuration into Key Vault

Create a new Key Vault to hold your configuration. You should have one Key Vault per environment that you intend to release to, since the secret names will directly translate to variables within VSTS. For each setting you need, create a secret with name like CustomSetting-Setting1 or CustomSetting-Setting2 and set their values. Next, in your ServiceConfiguration.Cloud.cscfg, set the values to be __CustomSetting-Setting1__ and __CustomSetting-Setting2__. The __ is the token start/end, and the value identifies which VSTS variable should be used to replace it.

One tip: If you have Password Encryption certificates or SSL endpoints configured, the .cscfg will have the certificates’ SHA-1 thumbprint’s encoded in them. If you want to configure this per environment, then replace those with token values. The configuration checker will enforce that it looks like a thumbprint, so use values like:

  • ABCDEF01234567ABCDEF01234567ABCDEF012345
  • BACDEF01234567ABCDEF01234567ABCDEF012345

Those sentinel values will be replaced with tokens during the build process and those tokens can be replaced with variable values.

We’ll use these in the build task later on.

The build definition

  1. Start with a new Empty build definition.
  2. On the process tab, choose the Hosted VS2017 Agent queue and give your build definition a name.
  3. Select Get Sources and point to your repository. This could be VSTS, GitHub or virtually any other location.
  4. Add the tasks we’ll need: Visual Studio Build (three times), Publish Build Artifacts (once). It should look something like this:
  5. For the first Visual Studio Build task, set the following values:
    Display nameRestore solution
    Visual Studio VersionVisual Studio 2017
    MSBuild Arguments/t:restore
  6. For the second Visual Studio Build task, use the following values:

    Display nameBuild solution
    Visual Studio VersionVisual Studio 2017
    MSBuild Arguments
  7. And the third Visual Studio Build task should be set as:

    Display namePublish Cloud Service
    Visual Studio VersionVisual Studio 2017
    MSBuild Arguments/t:Publish /p:OutputPath=$(Build.ArtifactStagingDirectory)\
  8. If you are using sentinel certificate values, add a PowerShell Task. Configure the PowerShell task by selecting “Inline Script”, expand Advanced and set the working folder to the publish directory (like $(Build.ArtifactStagingDirectory)\app.publish) and use the following script:

    $file = "ServiceConfiguration.Cloud.cscfg"
    # Read file
    $content = Get-Content -Path $file
    # substitute values
    $content = $content.Replace("ABCDEF01234567ABCDEF01234567ABCDEF012345", "__SslCertificateSha1__")
    $content = $content.Replace("BACDEF01234567ABCDEF01234567ABCDEF012345", "__PasswordEncryption__")
    # Save
    [System.IO.File]::WriteAllText($file, $content)

    This replaces the fake SHA-1 thumbprints with tokens that release management will use. Be sure to define variables in release management that match the names you use.

  9. Finally, set the Publish Artifact step to:

    Display namePublish Artifact: Cloud Service
    Path to Publish$(Build.ArtifactStagingDirectory)\app.publish
    Artifact NameTheCloudService
    Artifact TypeServer
  10. Go to the Variables tab and add two variables:

    BuildPlatformAny CPU
  11. Hit Save & Queue to save the definition and start a new build. It should complete successfully. If you go to the build artifacts folder, you should see TheCloudService with the .cspkg file in it.

Deploying the build to Azure

This release process depends on one external extension that handles the tokenization, the Release Management Utility Tasks. Install it from the marketplace into your VSTS account before starting this section.

  1. In VSTS, switch to the Releases tab and create a new release definition using the “Azure Cloud Service Deployment” template.
  2. Give the environment a name, like “Cloud Service – Prod”.
  3. Click the “Add artifact” box and select your build definition. Should look something like this:

    If you want continuous deployment, click the “lightning bolt” icon and enable the CD trigger.
  4. Click on the Tasks tab and specify an Azure subscription, storage account, service name and location. If you need to link your existing Azure subscription, click the “Manage” link. If you need a new storage account to hold the deployment artifacts, you can create that in the portal as well, just make sure to create a “Classic” storage account.
  5. Go to the Variables tab and select “Variable groups”, then “Manage variable groups.” Add a new variable group, give it a name like “AspNetCloudService Production Configuration”, select your subscription (click Manage to link one), and select the Key Vault we created earlier to hold the config. Press the Authorize button if prompted.

    Finally, click Add to select which secrets from Key Vault should be added to this variable group.

    It’s important to note that it does not copy the values at this point. The secret’s values are always read on use, so they’re always current. Save the variable group and return back to the Release Management definition. At this point, you can select “Link variable group” and link the one we just created.
  6. Add a Tokenize with XPath/Regular Expressions task before the Azure Deployment task.
  7. In the Tokenizer task, browse to the ServiceConfiguration.Cloud.cscfg file, something like $(System.DefaultWorkingDirectory)/AspNetCoreCloudService-CI/TheCloudService/ServiceConfiguration.Cloud.cscfg depending on what you call your artifacts.
  8. Ensure that the Azure Deployment task is last, and you should be all set.
  9. Create a new release and it should deploy successfully. If you view your cloud service configuration on Azure Portal, you should see the real values, not the __Tokenized__ values.


That’s it, you now have an ASP.NET Core Cloud Service deployed to Azure with CI/CD through VSTS. If you want to add additional environments, simply add an additional key vault and linked variable group for each environment, clone the existing environment configuration in the Release Management editor and set the appropriate environmental values. Variable groups are defined at the release definition level, so for multiple-environments you can use a suffix in your variable names and then update the PowerShell script in step 7 to append that per environment (__MyVariable-Prod__), etc.

Using ASP.NET Core with Azure Cloud Services

October 16, 2017 Coding 1 comment , ,

Using ASP.NET Core with Azure Cloud Services


Cloud Services may be the old-timer of Azure’s offerings, but there are still some cases where it is useful. For example, today, it is the only available PaaS way to run a Windows Server 2016 workload in Azure. Sure, you can run a Windows Container with Azure Container Services, but that’s not really PaaS to me. You still have to be fully aware of Kubernetes, DC/OS, or Swarm, and, as with any container, you are responsible for patching the underlying OS image with security updates.

In developing my Code Signing Service, I stumbled upon a hard dependency on Server 2016. The API I needed to Authenticode sign a file using Azure Key Vault’s signing methods only exists in that version of Windows. That meant that using Azure App Services was out, as it uses Server 2012 (based on the version numbers from its command line). That left Cloud Service Web Roles as the sole remaining option if I wanted PaaS. I could have also used a B-Series VM, that’s perfect for this type of workload, but I really don’t want to maintain a VM.

If you have tried to use ASP.NET Core with a Cloud Service Web Role, you’ll probably have come away disappointed as Visual Studio doesn’t let you do this…. until now. Never one to accept no for an answer, I found a way to make this work, and with a few workarounds, you can too.

The solution presented here handles deployment of an MVC & API application that along with config settings and deployment of the ASP.NET Core Windows Hosting Module. VS Cloud Service tooling works for making changes to config and publishing to cloud services (though please use CI/CD in VSTS!)

Many thanks to Scott Hunter‘s team, Jaques Eloff and Catherine Wang in particular, on figuring out a workaround for some gotcha’s when installing the Windows Hosting Module.

Pieces to the puzzle

You can see the sample solution here, and it may be helpful to clone and follow along in VS.

There are a few pieces to making this work:

  1. TheWebsite The ASP.NET Core MVC site. Nothing significantly special here, just an ordinary site.
  2. TheCloudService The Cloud Service project. Contains the configuration files and service definition.
  3. TheWebRole ASP.NET 4.6 project that contains the Web Role startup scripts and “references” the TheWebsite site. This is where the tricks are.

At a high level, the Cloud Service “sees” TheWebRole as the configured website. The cloud service doesn’t know anything about ASP.NET Core. The trick is to get the ASP.NET Core site published and running “in” an ASP.NET site.

Doing this yourself

The Projects

In a new solution, create a new ASP.NET Core 2 project. Doesn’t really matter what template you use. For the descriptions here, I’ll call it TheWebsite. Build and run the site, it should debug and run normally in IISExpress.

Next, create a new Cloud Service (File -> Add -> New Project -> Cloud -> Azure Cloud Service). I’ll call the cloud service TheCloudService, and on the next dialog, add a single Web Site. I called mine TheWebRole.

Finally, on the ASP.NET Template selection, choose “Empty” and continue.

Right now, we have an ASP.NET Core Website and an Azure Cloud Service with a single ASP.NET 4.6 WebRole. Next up is to clear out almost everything from TheWebRole since it won’t actually contain any ASP.NET Code. Delete the packages.config and Web.config files.

Save the project, then select “Unload” from the project’s context menu. Right-click again and select “Edit TheWebRole.csproj”. We need to delete the packages brought in by NuGet along with the imported props and target. There are three areas to delete as noted in the screen shots: Props at the top, all Reference elements with a HintPath pointing to ..\packages\ and the Target at the bottom.

At this point, your project file should look similar to this here. You can also view the complete diff.


Now comes the special sauce — we need a way to have TheWebRole build TheWebsite and include TheWebsite‘s publish output as Content. Doing this ensures that TheCloudService Package contains the correct folder layout. Add the following snippet to the bottom of TheWebRole‘s project file to call Publish on our website before the main build step.

<Target Name="BeforeBuild">
  <MSBuild Projects="..\TheWebsite\TheWebsite.csproj" Targets="Publish" Properties="Configuration=$(Configuration)" />

Then, add the following ItemGroup to include TheWebsite‘s publish output as Content in the TheWebRole project:

  <Content Include="..\TheWebsite\bin\$(Configuration)\netcoreapp2.0\publish\**\*.*" Link="%(RecursiveDir)%(Filename)%(Extension)" />

Save the csproj file, then right-click the TheWebRole and click Reload. You can test that the cloud service package is created correctly by right-clicking TheCloudService and selecting Package. After choosing a build configuration and hitting “Package,” the project should build and the output directory pop up.

The .cspkg is really a zip file, so extract it and you’ll see the guts of cloud service packages. Look for the .cssx file and extract that (again, just a zip file)

Inside there, open the approot folder and that is the root of your website. If the previous steps were done correctly, you should see something like the following

You should see TheWebsite.dll, TheWebsite.PrecompiledViews.dll, wwwroot, and the rest of your files from TheWebsite.

Congratulations, you’ve now created a cloud service that packages up and deploys an ASP.NET Core website! This alone won’t let the site run though since the Cloud Service images don’t include the Windows Hosting Module.

Installing .NET Core 2 onto the Web Role

Installing additional components onto a Web Role typically involves a startup script, and .NET Core 2 is no different. There is one complication though: the installer downloads files into the TEMP folder, and Cloud Services has a 100MB hard limit on that folder. We need to specify an alternate folder to use as TEMP with a higher quota (this is what Jaques and Catherine figured out).

In TheCloudService, expand Roles, right click TheWebRole and hit properties. Go to Local Storage and add a new location called CustomTempPath with a 500MB limit (or whatever else your app might need).

Next, we need the startup script. Go to TheWebRole, add a new folder called Startup and add the following files to it. Ensure that the Build Action is set to Content and that Copy to Output Directory is set to Copy if newer. Finally, we need to configure the cloud service to invoke our startup task. Open the ServiceDefinition.csdef file and add the following xml in the WebRole node to define the startup task:

  <Task commandLine="Startup\startup.cmd" executionContext="elevated" taskType="simple">
    <Variable name="IsEmulated">
      <RoleInstanceValue xpath="/RoleEnvironment/Deployment/@emulated" />

Now we finally have a cloud service that can be deployed, install .NET Core, and run the website. The first time you publish, it will take a few minutes for the role instance to become available since it
has to install the hosting module and restart IIS.

Note: I leave creating a cloud service instance in the Azure Portal as an exercise to the reader


There are many ways of getting configuration into an ASP.NET Core application. If you know you’ll only be running in Cloud Services, you may consider taking a direct dependency on the Cloud Services libraries and using the RoleEnvironment types to get populate your configuration. Alternatively, you can likely write a configuration provider that funnels in the RoleEnvironment configuration into the ASP.NET Core configuration system.

In my original case, I didn’t want my ASP.NET Core website to have any awareness of Cloud Services, so I came up with another way—in the startup script, I copy the values from the RoleEnvironment into environment variables that the default configuration settings pick up. The key here to making this transparent is knowing that the double-underscore, __, translates into the : when read from an environment variable. This means you can define a setting like CustomSetting__Setting1, and then you can access it with Configuration["CustomSetting:Setting1"], or similar mechanisms.

To bridge this gap, we can add this to the startup script (complete script):

$keys = @(

foreach($key in $keys){
  [Environment]::SetEnvironmentVariable($key, [Microsoft.WindowsAzure.ServiceRuntime.RoleEnvironment]::GetConfigurationSettingValue($key), "Machine")

This copies the settings from the Cloud Service Role Environment into environment variables on the host, and from there, the default ASP.NET Core configuration adds them into configuration.


  • Session affinity If you need session affinity for session state, you’ll need to configure that.
  • Data Protection API Unlike Azure App Services, Cloud Services doesn’t have any default synchronization for the keys. You’ll need a solution for this. If anyone comes up with a reusable solution, I’ll happily mention it here. More info on configuring DPAPI is here.
  • Local Debugging Due to the way local debugging of cloud services works (it directly uses TheWebRole as a startup project in IIS Express), directly debugging the cloud service does not work with the current patterns. Instead, you can set TheWebsite as a startup project and debug that normally. The underlying issue is that TheWebRole includes TheWebsite as Content and does not copy the published files to TheWebRole‘s directory. It may be possible to achieve this, though you’d likely want additional .gitignore rules to prevent those files from being committed. In my case, I did not want my service to have any direct dependency on Cloud Services, so this wasn’t an issue—I simply needed a Server 2016 web host.

CI / CD with VSTS

It is possible to automate build/deploy of these cloud service web role projects using VSTS. My next blog post will show how to set that up.

Update October 18: The post is live

Use all TFM’s with SDK-style projects in Visual Studio for Mac

August 29, 2017 Coding 4 comments , , ,

Use all TFM’s with SDK-style projects in Visual Studio for Mac


You can now use SDK-style projects, with all supported TFM’s, in Visual Studio for Mac. See getting started for details.


While Visual Studio for Mac supports the SDK-style projects, there have been a couple of issues blocking use of TFM’s other than net, netstandard, and netcoreapp.

  1. Those TFM’s are hard-coded and an SDK-style project containing any other target frameworks is blocked.
  2. Xamarin on the Mac has a multi-valued MSBuildExtensionsPath property. That means that it can search for targets in different locations. Unfortunately the logic this works with is limited to the <Import /> element, so if you set properties, as is required to use LanguageTargets, it won’t work. Fortunately, with some brainstorming with Ankit Jain and Mikayla Hutchinson, we found a solution.

Getting Started

You’ll need a few things:

  1. Latest stable channel of Visual Studio for Mac
  2. .NET Core 2 SDK (even if you’re not targeting .NET Standard 2 or .NET Core, the SDK style projects use these targets). Download here.
  3. Matt Ward‘s Extension to VSfM that removes TFM checks on SDK-style projects. Binary | Source. Install by going to Visual Studio -> Extensions... -> Install from file...

Then, create a new SDK-style project and use the latest version of the MSBuild.Sdk.Extras package, at least version 1.1.0-beta.69:

<PackageReference Include="MSBuild.Sdk.Extras" Version="1.1.0-beta.69" PrivateAssets="all" />

At the end of the project file, just before the closing tag, you’ll also need the following, as per the MSBuild SDK Extras readme:

<Import Project="$(MSBuildSDKExtrasTargets)" Condition="Exists('$(MSBuildSDKExtrasTargets)')" />

Here’s a complete example of using the SDK-style projects with an iOS class library:

<Project Sdk="Microsoft.NET.Sdk">

    <PackageReference Include="MSBuild.Sdk.Extras" Version="1.1.0-beta.69" PrivateAssets="all" />

  <Import Project="$(MSBuildSDKExtrasTargets)" Condition="Exists('$(MSBuildSDKExtrasTargets)')" />

Building these projects

These projects will build in the IDE (VSfM, VS, etc) or the command line. If you use the command line, you must use msbuild, not dotnet build. Keep in mind that with msbuild, you must explicitly call restore first, so your build steps will look like this:

msbuild /t:restore
msbuild /p:Configuration=Release


For the beta, since it’s a SemVer2 package, you must be using the NuGet v3 feed. If your VSfM prefs have https://www.nuget.org/api/v2/, you need to update that to be https://api.nuget.org/v3/index.json.


If you run into issues, please file a bug on the MSBuild SDK Extras project site: https://github.com/onovotny/MSBuildSdkExtras/issues and reach
me @onovotny.

Announcing Reactive Extensions for .NET 4.0 Preview 1

May 27, 2017 Coding 1 comment , , ,

Announcing Reactive Extensions for .NET 4.0 Preview 1!

I am happy to announce that the first preview of Rx.NET 4.0 is now available. This release addresses a number of issues and contains several enhancements.

The biggest enhancement is consolidating the existing packages into one main package, System.Reactive NuGet. This will prevent most of the pain around binding redirects that were caused by #205. If you are using Rx 4.0 and need to use libraries built against Rx 3.x, then you need to also install the compatibility package System.Reactive.Compatibility. That package contains facades with type forwarders to the new assembly so types are unified correctly. You only need this compatibility package if you are consuming a library built against 3.x. You do not need it otherwise.

If you’re interested in the background behind the version numbers, I suggest reading the thread as it contains the gory details. While the idea was technically sound, it did mean that binding redirects were required for all .NET Framework uses. We heard the feedback loud and clear that this was really painful and took steps to fix it in 4.0.

The fix was to consolidate the previous set of packages into a single System.Reactive package. With the single package, binding redirects are no longer required and the platforms will get the correct Rx package version.

Please try it out and let us know if you encounter any issues at our repo. The full release notes are there too.

Multi-targeting the world: a single project to rule them all

January 4, 2017 Coding 9 comments , , , , , , ,

Multi-targeting the world: a single project to rule them all

Starting with Visual Studio 2017, you can now use a single project to build platform-specific libraries for all project types. This blog will explore why you might want to do this, how to do it and workarounds for some point-in-time issues with the tooling.



Since the beginning of .NET Core, the project.json format has enabled multi-targeting, that is compiling to multiple target frameworks in parallel and creating an output for each. With ASP.NET Core, it’s common to target both net45 and netcoreapp1.0 so you can deploy the site to either the desktop framework, which runs on Windows, or to the CoreCLR, which runs cross-platform. Multi-targeting is nothing more than compiling the same code multiple times, once per target platform. Each target can specify its own dependencies and ifdef‘s, so you can easily tailor the code to the specific platform.

Another example may have a library target netstandard1.0, netstandard1.3, and net45 to enable different levels of functionality based on the available surface area.

While it was also possible to target UWP, Win8, or profile-based PCL’s, using project.json, doing so required hacks like private copies of all reference assemblies, WinMD files and more. Beyond that, some things didn’t work correctly as some platforms require additional targets to generate additional outputs like .pri files on UWP for resource lookup. So while technically possible, full multi-targeting was brittle and required you to stay in a very narrow path, avoiding things like resources or GUI elements that require the full tool-chain to process.

Enter MSBuild

With the move to MSBuild as part of the .NET Core Tooling direction change, the picture gets much better, so much so that with VS 2017 RC2, you can correctly multi-target all platform types, including UWP, profile-based PCL’s, and Xamarin iOS/Android. Not only that, but by conditionally including/excluding directories based on globs, you can reduce the need for ifdef‘s in many cases.

As part of being open sourced and enabled to run cross-platform, the build targets and tasks required to actually do the build were combined into an SDK. This went along with drastic simplification of the csproj file to have a minimal footprint, that will get even smaller, like this:

<Project Sdk="Microsoft.NET.Sdk">
    <PackageReference Include="Microsoft.NETCore.App" Version="1.0.1" />

Microsoft’s blog details all of the improvements in this area. For current lack of a better term, I’ll call projects based on these new tools “SDK style.” The easiest way to identify these “SDK style” projects is by looking for the Sdk attribute in the top Project element.

Multi-targeting vs. .NET Standard Libraries vs. PCL’s

Before we go further, let’s answer this question that many people have asked — why would you want to multi-target vs just use a single portable library, whether that’s .NET Standard or an older profile-based PCL?

There are several answers to that question — first, if your code can all fit within a single .NET Standard-based library, then there’s no reason to multi-target. If you’re using a legacy profile-based PCL, at the very least consider moving up to the equivalent .NET Standard version. Don’t make more work for yourself. The decision to multi-target falls out of a need to use functionality that doesn’t exist within a .NET Standard version or if you need to target an earlier platform that doesn’t support the .NET Standard version you need. A common example is that many libraries still need to support .NET 4.5. Despite a significant amount of functionality available in .NET Standard 1.3, that .NET Standard version only supports .NET 4.6+. Chances are though that the code would work “just fine” on .NET 4.5, so it’s easy to multi-target to both net45 and netstandard1.3.

The other main reason why you’d need to multi-target is to use platform-specific code within your library. For example, on iOS you might want to use SecKeyChain for saved credentials, on Android use its Context to access shared services like preferences, and on Windows its Credential Manager. You might have a common method called GetCredential that other code uses to get the data. Today you might use dependency injection or reflection to access a “.Platform” library with a specific implementation that your common code uses. Instead, you can choose to multi-target and access the platform code directly.

How to multi-target

Let me start by saying that the methods here are based on the new “SDK-style” projects that VS 2017 provides. They orchestrate using the existing project types that are installed by Visual Studio. As such, the build itself won’t work on a box without the other tools installed (so you’re building on a Windows box, much like you probably are today). Some of these may work on a Mac with Visual Studio for Mac but I have not tested that in any way. When you install Visual Studio 2017, make sure to install all of the tools for the project types you need (Xamarin, UWP, etc) and also the .NET Core Tooling.

There’s no UI in VS for adding additional target frameworks, but I have some samples that show what to do.

First, create a new .NET Core Class Library project. If you don’t see the following option, make sure to install the .NET Core workload in the VS Installer.

New .NET Core Class Library
.NET Core workload

Right-click the project and select “Edit project file…”. This is new in VS 2017 – the ability to edit the project file while it’s open and have changes instantly reflected.

In the editor, after noticing how much less boilerplate code there is now, look for the TargetFramework property that looks like this: <TargetFramework>netstandard1.3</TargetFramework> property. Change that to <TargetFrameworks>netstandard1.3;net45</TargetFrameworks> to target .NET 4.5 and NET Standard 1.3. You can add however many targets you want by adding to that semi-colon list. It’s subtle, but note the difference in property names between TargetFramework and TargetFrameworks with a plural. It’s easy to miss.

For some frameworks, like .NET 4.5, that’s all you need to do. However, targeting .NET Standard and .NET 4.x is far from “the world.” We can do better! You would think it should be as easy as adding additional TFM’s like uap10.0, xamarin.ios10 or MonoAndroid70 to the list, and hopefully by the time the tools RTM it will be, but for now we need to add extra properties to the project file to tell MSBuild what to do with those.

Fortunately, and here’s the real secret, the “SDK-style” build system has a LanguageTargets property that you can specify per TFM to import the targets for that project type instead of the vanilla Microsoft.CSharp.targets import. That means we can use the “Windows Xaml”, Android, iOS, or any other platform tool-chain we need.

Xamarin Example

In the example here, I have a class library that multi-targets to net45, uap10.0, netstandard1.3, Xamarin.iOS10 and MonoAndroid70. In this contrived library, I have a Greeter class that’s calling a Hello() method that needs platform specific code. I’m using a pattern where I have a directory for each TFM where code in there only gets included there, so no ifdef‘s are needed. For Android, Resources are supported if you need them. While the example doesn’t currently use them, you could use PList‘s, xib‘s or Story Boards on iOS, Page‘s on UWP, or any other “native” file type supported by the platform.

Win81/WP8/PCL/Wpa81/Xamarin/Net45 Example

As a more realistic example, one of my libraries, Zeroconf, an mDNS discovery library, targets “the world.” It currently has concrete implementations for wp8, Wpa81, Win8, portable-Wpa81+Win81, uap10.0, net45, and netstandard1.3 (which supports Xamarin and CoreCLR.) In addition to the the concrete implementations, it provides a netstandard1.0 fa├žade to support being used in portable libraries. The different concrete implementations are required due to differences in the networking stacks between the various Windows networking stacks. For now, the uap10.0 version cannot use the netstandard1.3 version until NetworkInformation is fully supported by the platform, so it continues to use the WinRT variant. You can see the platform-specific code in the platforms directory and then how they’re conditionally included by the csproj in the ItemGroups

The property groups at the top contain the LanguageTargets and properties needed. For portable-Wpa81+Win81 two extra items are required as the special PCL profile also supports WinRT. The ItemGroup here has two TargetPlatform to pull in the correct .winmd references.


You can build the libraries either in VS 2017 or the command-line. If you use the command line, you’ll want to run the following from a VS 2017 Developer Command Prompt: msbuild /t:restore followed by msbuild /t:build. If you want to create a NuGet package, you can run msbuild /t:pack. It’s important to note that you must currently use msbuild, the desktop version in the VS 2017 path, to build these and not dotnet build. The reason is that while dotnet build calls MSBuild, it’s currently using a CoreCLR version even though the desktop version is present in your VS installation. The engineering team is aware of this and in the future, dotnet build will be smart enough to call the desktop version of msbuild when present. The “regular” targets file we’re using to support the platform-specific features are designed for Desktop MSBuild. They do not yet have support for CoreCLR tasks. Bottom line, as of the current release: if your targets use build tasks, then you need to provide both CoreCLR and Desktop versions of the library in order to support both “regular” MSBuild and dotnet build.

Common gotcha’s

There are several bugs in the tool-chain currently that are in the process of being fixed:

  • Some Project-to-project (p2p) references aren’t resolving correctly. Whereas they should resolve to the “best” match, they are resolving to the first TFM in the list.
  • Another bug is preventing a “legacy” csproj from doing a p2p reference with a “Portable Library can only reference other portable library” error.
  • Files that are conditionally included won’t show up in the Solution Explorer. As a workaround, include all files with None as the first item group (see example).
  • for iOS (and possibly Android), you need to set DebugType to full as the Xamarin ConvertPdb2Mdb task doesn’t yet support the new Portable PDB format generated by this tool-chain.
  • Win8, Win81, and uap10.0 aren’t correctly understood by the NuGet targets today. As a workaround, you need to include the NugetTargetMoniker property set to the full TFM as shown here. Similarly, for legacy PCL targets, it requires Version=v0.0 in the NugetTargetMoniker here. These should hopefully be fixed by GA.
  • Windows assemblies that use resources need a .pri file alongside them. They’re currently missing from the generated NuGet. Workaround is to use your own .NuSpec for now until the bug is fixed.

Into the weeds, how it all works

This is by no means an official explanation, it’s what I’ve found from exploring the SDK build targets. Some of the terminology and concepts may change over time.

The “SDK style” projects consist of a set of targets/tasks that are pre-installed with MSBuild (and the CLI tools). You can see them in the following directory: C:\Program Files (x86)\Microsoft Visual Studio\2017\<sku>\MSBuild\Sdks where <sku> is Community, Professional, or Enterprise, depending on what you installed. The two SDK’s you’re likely to use directly are Microsoft.NET.Sdk and Microsoft.NET.Sdk.Web.

The Sdk attribute causes an Sdk.props and Sdk.targets within the specified SDK’s \Sdk directory to be imported before and after the project file. The Microsoft.NET.Sdk SDK’s targets defines an “outer” and “inner” build. The “outer-loop” is what your project file directly defines, including several TFM’s in the TargetFrameworks property. If you only have a single build with a TargetFramework property defined, then there’s only an “inner-loop”.

For an “outer-loop” build, the SDK targets imports props/targets in a buildCrossTargeting directory (soon to be renamed to buildMultiTargeting). Those get auto-included before and after the main project file (props before, targets after.) The “outer-loop” targets will eventually loop through each of the TargetFrameworks calling msbuild again in an “inner-loop” with TargetFramework set to one TFM. This “inner-loop” build is what we currently have in today’s “normal” project types. The “inner-loop” build provides an extension point for providing your language-specific targets (the Import that was at the bottom of your old csproj before) in place of the “vanilla” one it’ll include by default. By providing a LanguageTargets property for the “inner-loop,” conditioned by TFM, we can use the “original” targets that invoke the full tool-chain for the target platform. See here, here and here for UWP, iOS, and Android, respectively.

Within each conditionally defined property group, we can set properties that are specific to a particular “inner-loop.” These correspond to the properties in your existing platform-specific project file and are used by the platform-specific targets specified.

One thing you give-up currently is any UI in VS for configuring these properties. Perhaps they’ll return sometime in the future. For now, one thing I’ve found helpful is to maintain a few “dummy” projects where I can edit some settings to see the values and then put them into my multi-targeting csproj.

Looking forward

As of today (January 4, 2017), the tooling is in a fairly rough state. The .NET Core tooling is rightfully in an “alpha” state. The MSBuild SDK is under active development and things will change before GA. There are a number of issues in the tooling that can make it hard to use today, but I expect those to be fixed soon. Most of the bugs I’ve found are slated to be fixed in the RC3 time-frame, and I’d expect things to be better with that release.

As to whether-or-not to take the plunge today: I’d suggest that if you have a tolerance for figuring this out and reporting issues you’ll encounter, then go for it. If you have a complex project today that already multi-targets a different way (most likely by using multiple “head” projects and shared code project types), I would recommend trying this out in a branch to see how far you get. I’ll be happy to help, just give me a shout. The more the community bangs on this stuff up front, the more issues can be addressed prior to GA.


Many thanks to Brad Wilson, Joe Morris, and Daniel Plaisted for reviewing this post and providing feedback.

Authenticode Signing Service and Client

September 12, 2016 Coding 1 comment , , , , ,

Authenticode Signing Service and Client

Last night I published a new project on GitHub to make it easier to integrate Authenticode signing into a CI process by providing a secured API for submitting artifacts to be signed by a code signing cert held on the server. It uses Azure AD with two application entries for security:

  1. One registration for the service itself
  2. One registration to represent each code signing client you want to allow

Azure AD was chosen as it makes it easy to restrict access to a single application/user in a secure way. Azure App Services also provide a secure location to store certificates, so the combination works well.

The service currently supports either individual files, or a zip archive that contains supported files to sign (works well for NuGet packages). The service code is easy to extend if additional filters or functionality is required.

Supported File Types

  • .msi, .msp, .msm, .cab, .dll, .exe, .sys, .vxd and Any PE file (via SignTool)
  • .ps1 and .psm1 via Set-AuthenticodeSignature


You will need an Azure AD tenant. These are free if you don’t already have one. In the “old” Azure Portal, you’ll need to
create two application entries: one for the server and one for your client.

Azure AD Configuration


Create a new application entry for a web/api application. Use whatever you want for the sign-on URI and App ID Uri (but remember what you use for the App ID Uri as you’ll need it later). On the application properties, edit the manifest to add an application role.

In the appRoles element, add something like the following:

  "allowedMemberTypes": [
  "displayName": "Code Sign App",
  "id": "<insert guid here>",
  "isEnabled": true,
  "description": "Application that can sign code",
  "value": "application_access"

After updating the manifest, you’ll likely want to edit the application configuration to enable “user assignment.” This means that only assigned users and applications can get an access token to/for this service. Otherwise, anyone who can authenticate in your directory can call the service.


Create a new application entry to represent your client application. The client will use the “client credentials” flow to login to Azure AD
and access the service as itself. For the application type, also choose “web/api” and use anything you want for the app id and sign in url.

Under application access, click “Add application” and browse for your service (you might need to hit the circled check to show all). Choose your service app and select the application permission.

Finally, create a new client secret and save the value for later (along with the client id of your app).

Server Configuration

Create a new App Service on Azure (I used a B1 for this as it’s not high-load). Build/deploy the service however you see fit. I used VSTS connected to this GitHub repo along with a Release Management build to auto-deploy to my site.

In the Azure App Service, in the certificates area, upload your code signing certificate and take note of the thumbprint id. In the Azure App Service, go to the settings section and add the following setting entries:

CertificateInfo:Thumbprintthumbprint of your certThumbprint of the cert to sign with
CertificateInfo:TimeStampUrlurl of timestamp server
WEBSITE_LOAD_CERTIFICATESthumbprint of your certThis exposes the cert’s private key to your app in the user store
Authentication:AzureAd:AudienceApp ID URI of your service from the application entry
Authentication:AzureAd:ClientIdclient id of your service app from the application entry
Authentication:AzureAd:TenantIdAzure AD tenant IDeither the guid or the name like mydirectory.onmicrosoft.com

Enable “always on” if you’d like and disable PHP then save changes. Your service should now be configured.

Client Configuration

The client is distributed via NuGet and uses both a json config file and command line parameters. Common settings, like the client id and service url are stored in a config file, while per-file parameters and the client secret are passed in on the command line.

You’ll need to create an appsettings.json similar to the following:

  "SignClient": {
    "AzureAd": {
      "AADInstance": "https://login.microsoftonline.com/",
      "ClientId": "<client id of your client app entry>",
      "TenantId": "<guid or domain name>"
    "Service": {
      "Url": "https://<your-service>.azurewebsites.net/",
      "ResourceId": "<app id uri of your service>"

Then, somewhere in your build, you’ll need to call the client tool. I use AppVeyor and have the following in my yml:

    secure: <the encrypted client secret using the appveyor secret encryption tool>

  - cmd: appveyor DownloadFile https://dist.nuget.org/win-x86-commandline/v3.5.0-rc1/NuGet.exe
  - cmd: nuget install SignClient -Version 0.5.0-beta3 -SolutionDir %APPVEYOR_BUILD_FOLDER% -Verbosity quiet -ExcludeVersion -pre


  - cmd: nuget pack nuget\Zeroconf.nuspec -version "%GitVersion_NuGetVersion%-bld%GitVersion_BuildMetaDataPadded%" -prop "target=%CONFIGURATION%" -NoPackageAnalysis
  - ps: '.\SignClient\SignPackage.ps1'
  - cmd: appveyor PushArtifact "Zeroconf.%GitVersion_NuGetVersion%-bld%GitVersion_BuildMetaDataPadded%.nupkg"  

SignPackage.ps1 looks like this:

$currentDirectory = split-path $MyInvocation.MyCommand.Definition

# See if we have the ClientSecret available
    Write-Host "Client Secret not found, not signing packages"

# Setup Variables we need to pass into the sign client tool

$appSettings = "$currentDirectory\appsettings.json"

$appPath = "$currentDirectory\..\packages\SignClient\tools\SignClient.dll"

$nupgks = ls $currentDirectory\..\*.nupkg | Select -ExpandProperty FullName

foreach ($nupkg in $nupgks){
    Write-Host "Submitting $nupkg for signing"

    dotnet $appPath 'zip' -c $appSettings -i $nupkg -s $env:SignClientSecret -n 'Zeroconf' -d 'Zeroconf' -u 'https://github.com/onovotny/zeroconf' 

    Write-Host "Finished signing $nupkg"

Write-Host "Sign-package complete"

The parameters to the signing client are as follows. There are two modes, file for a single file and zip for a zip-type archive:

usage: SignClient <command> [<args>]

    file    Single file
    zip     Zip-type file (NuGet, etc)

File mode:

usage: SignClient file [-c <arg>] [-i <arg>] [-o <arg>] [-h <arg>]
                  [-s <arg>] [-n <arg>] [-d <arg>] [-u <arg>]

    -c, --config <arg>            Full path to config json file
    -i, --input <arg>             Full path to input file
    -o, --output <arg>            Full path to output file. May be same
                                  as input to overwrite. Defaults to
                                  input file if ommited
    -h, --hashmode <arg>          Hash mode: either dual or Sha256.
                                  Default is dual, to sign with both
                                  Sha-1 and Sha-256 for files that
                                  support it. For files that don't
                                  support dual, Sha-256 is used
    -s, --secret <arg>            Client Secret
    -n, --name <arg>              Name of project for tracking
    -d, --description <arg>       Description
    -u, --descriptionUrl <arg>    Description Url

Zip-type archive mode, including NuGet:

usage: SignClient zip [-c <arg>] [-i <arg>] [-o <arg>] [-h <arg>]
                  [-f <arg>] [-s <arg>] [-n <arg>] [-d <arg>] [-u <arg>]

    -c, --config <arg>            Full path to config json file
    -i, --input <arg>             Full path to input file
    -o, --output <arg>            Full path to output file. May be same
                                  as input to overwrite
    -h, --hashmode <arg>          Hash mode: either dual or Sha256.
                                  Default is dual, to sign with both
                                  Sha-1 and Sha-256 for files that
                                  support it. For files that don't
                                  support dual, Sha-256 is used
    -f, --filter <arg>            Full path to file containing paths of
                                  files to sign within an archive
    -s, --secret <arg>            Client Secret
    -n, --name <arg>              Name of project for tracking
    -d, --description <arg>       Description
    -u, --descriptionUrl <arg>    Description Url


I’m very much open to any collaboration and contributions to this tool to enable additional scenarios. Pull requests are welcome, though please open an issue to discuss first. Security reviews are also much appreciated!

Using Xamarin Forms with .NET Standard

July 9, 2016 Coding 10 comments , , , ,

Using Xamarin Forms with .NET Standard

With the release of .NET Core and the .NET Standard Library last week, many people want to know how they can use packages targeting netstandard1.x with their Xamarin projects. It is possible today if you use Visual Studio; for Xamarin Studio users, support is coming soon.


Using .NET Standard pretty much requires you to use project.json to eliminate the pain of “lots of packages” as well as properly handle transitive dependencies. While you may be able to use .NET Standard without project.json, I wouldn’t recommend it.

You’ll need to use the following tools:

Getting Started

As of now, the project templates for creating a new Xamarin Forms project start with an older-style packages.config template, so whether you create a new project or have an existing project, the steps will be pretty much the same.

Step 1: Convert your projects to project.json following the steps in my previous blog post.

Step 2: As part of this, you can remove dependencies from your “head” projects that are referenced by your other projects you reference. This should simplify things dramatically for most projects. In the future, when you want to update to the next Xamarin Forms version, you can update it in one place, not 3-4 places. It also means, you only need the main Xamarin.Forms package, not each of the packages it pulls in.

If you hit any issues with binaries not showing up in your bin directories (for your Android and iOS “head” projects), make sure that you have set CopyNuGetImplementations to true in your csproj as per the steps in the post.

At this point, your project should be compiling and working, but not yet using netstandard1.x anywhere.

Step 3: In your Portable Class Library projects, find the highest .NET Standard version you need/want to support.

Here’s a cheat sheet:

  • If you only want to support iOS and Android, you can use .NET Standard 1.6. In practicality though, most features are currently available at .NET Standard 1.3 and up.
  • If you want to support iOS, Android and UWP, then NET Standard 1.4 is the highest you can use.
  • If you want to support Windows Phone App 8.1 and Windows 8.1, then NET Standard 1.2 is your target.
  • If you’re still supporting Windows 8, .NET Standard 1.1 is for you.
  • Finally, if you need to support Windows Phone 8 Silverlight, then .NET Standard 1.0 is your only option.

Once you determine the netstandard version you want, in your PCL’s project.json, change what you might have had:

    "dependencies": {
        "Xamarin.Forms": ""        
    "frameworks": {        
        ".NETPortable,Version=v4.5,Profile=Profile111": { }
    "supports": { }


    "dependencies": {
        "NETStandard.Library": "1.6.0",
        "Xamarin.Forms": ""        
    "frameworks": {        
        "netstandard1.4": {
            "imports": [ "portable-net45+wpa81+wp8+win8" ]
    "supports": { }

Note the addition of the imports section. This is required to tell NuGet that specified TFM is compatible here because the Xamarin.Forms package has not yet been updated to use netstandard directly.

Then, edit the csproj to set the TargetFrameworkVersion element to v5.0 and remove any value from the TargetFrameworkProfile element.

At this point, when you reload the project, it should restore the packages and build correctly. You may need to do a full clean/rebuild.

Seeing it in action

I created a sample solution showing this all working over on GitHub. It’s a good idea to clone, build and run it to ensure your environment and tooling is up-to-date. If you get stuck converting your own projects, I’d recommend referring back to that repo to find the difference.

As always, feel free to tweet me @onovotny as well.

UWP NuGet Package Dependencies

August 29, 2015 Coding 4 comments , , ,

UWP NuGet Package Dependencies

[Updated: 9/15/15 on the NuGet package contents at the end]

In my last post, Targeting .NET Core, I mentioned that NuGet packages targeting .NET Core and using the dotnet TFM need to list their dependencies. What may not be immediately obvious, as this is new behavior for UWP projects, is that UWP packages need to list their BCL dependencies too, not just “regular” NuGet references.

The reason for this is that UWP projects also use .NET Core and may elect to use newer BCL package versions than the default. While the uap10.0 TFM does imply BCL + Windows Runtime, it doesn’t really say what version of the dependencies you get. Instead, that’s in your project.json file, which by default includes the Microsoft.NETCore.UniversalWindowsPlatform v5.0.0 “meta-package”, which pulls in most of the .NET Core libraries at a particular version. But what happens if newer BCL packages are published? Right now, the OSS BCL .NET Core packages are being worked on and they’re a higher version – System.Runtime is 4.0.21-beta*.

In Windows 8.1 and Windows 8, this wasn’t an issue because those platforms each had a fixed set of BCL references. You’d know for sure what BCL version’s you’d get for each of those. But now with UWP, that’s no longer true, so you need to specify them.

Fortunately, you don’t have to figure out all of the dependencies by hand. Instead, you can use my handy NuSpec.ReferenceGenerator tool (NuGet|GitHub) to add those dependencies to your NuSpec file.

The ReadMe is fairly detailed, but for the majority of projects, if you have a NuSpec file whose filename matches your project name (like MyAwesomeLibrary.csproj with a MyAwesomeLibrary.nuspec sitting somewhere under the .sln dir), adding the reference should be all you need.

For a UWP Class Library package, you should have the following in your NuSpec:

  • A dependency group with the uap10.0 TFM
  • In your Project Build options for Release mode, choose “generate library layout”
  • Copy the entire directory structure of the output to your \lib\uap10.0 dir.

Targeting .NET Core

July 29, 2015 Coding 7 comments , , , ,

Targeting .NET Core


Since DNX was announced, library authors have been inundated with requests to support .NET Core and the CoreCLR. Up until now, the only real option was to use the DNX-based project.json build system with the Visual Studio xproj projects. Adding these project types into an existing project that already supports a wide-range of platform targets can be challenging. There are a few issues with the current approach:
– Not all project types can be built with project.json
– It’s been a moving target as DNX is rightfully still in beta.
– Without proper guidance, authors have been targeting dnxcore50 in their packages intended for .NET Core instead of dotnet
– To be fair, dotnet is a recent update that has been little publicized

Starting today though, there’s a better way. Just make sure to install the Windows developer tooling as it includes this new functionality.


If we go back to the .NET Core presentation back in November, you may remember this diagram:

In terms of terminology, .NET Core should be your target; CoreCLR is just a runtime. Referring to the diagram, the dnxcore50 Target Framework Moniker refers to the box in the upper-right — it’s the ASPNet 5 app model. It is BCL + DNX specific libraries. Similarly, uap10.0 is the Windows Universal app model, BCL + Windows Runtime.

Many (most?) libraries do not actually need the DNX or WinRT dependencies. All they really need are the BCL libraries. What then is the target there? The answer is dotnet. By using dotnet, you instead specify your dependencies in your nuget package and your package will then run on any supported runtime, including CoreCLR, .NET Native and .NET 4.6 (assuming you’re using the newest BCL packages.)

Existing Libraries

What has been lost in the commotion around DNX, CoreCLR and .NET Core is the fact that “Profile 259″+ Portable Class Libraries, class libraries that target a minimum of .NET 4.5, Windows 8 and Windows Phone 8, can run on CoreCLR as-is. You do not need to create a new project or target newer contract/BCL references. All you need is to put your existing library into \lib\dotnet in your NuGet package in addition to the \lib\portable-* directory it is now and list your dependencies in the package.

The only time you might need a new project is if you have platform-specific code. In that case, the new UWP tools for Windows 10 has a better option: “Modern PCLs”. Once you install the UWP tools, create a new Class Library (Portable) in your solution and make sure only .NET 4.6, Windows Universal 10 and ASP Net 5 is checked. When you do that, you’ll get a modern PCL that uses project.json and pulls in the newest .NET Core packages as references. You can then use linked files, shared projects and your existing techniques to build a class library that targets .NET Core. Then, put that in your \lib\dotnet directory and create the dependencies element for it. No magic needed. Using this technique, I was able to adapt several OSS libraries to support .NET Core in very little time.

NuGet Dependencies – the heart of dotnet

As I described in my previous post, the key to making dotnet work is specifying all of your dependencies. This can be a tedious and error-prone process. I’ve built a tool, NuGet.ReferenceGenerator that automates creation of the dependency element for the majority of cases. The tool works with either existing compatible PCL projects and the new “modern PCL” projects.

Just add the NuSpec.ReferenceGenerator NuGet to your package and build. I won’t go over all of the docs, but you can find those on the project site.

At build time, the tool will read the references your assembly requires, determine the source NuGet package and version, and create the <dependencies> element in the NuSpec.

Call To Action

  • If you maintain a library, review any areas where you are currently targeting dnxcore50 and update your NuGet package to put those bits in dotnet. If you are not using any Microsoft.Dnx references, and the majority of libraries do not, then there’s no reason to target dnxcore50 when dotnet reaches a far broader set of targets.
    • Bonus by using the “Modern PCL” projects and/or reusing your existing PCL, your dependencies will be the stable versions, not pre-release. That means your package can be stable too and not wait until Q1 2016!.
  • If you currently have a library that’s a “System.Runtime”-based PCL, one that’s at least portable-win8+net45+wp8, then simply add a copy of the binary to your NuGet package in the dotnet directory. Adding it to \lib\dotnet and leaving a copy in lib\portable-win8+net45+wp8 allows it to work with .NET Core and the existing NuGet v2 clients.
  • Ensure your NuGet package lists all of its dependencies in a <dependencies targetFramework="dotnet"> element. Use the stable package versions, not the DNX pre-release versions. If you don’t want to create and maintain this by hand, use my ReferenceGenerator.
  • Last, but most importantly, make sure your nuget.exe version is up-to-date by running nuget update -self. Version 2.8.6 or later is required to properly package dotnet.