Build, test, and deploy .NET Core apps

Azure DevOps Services | Azure DevOps Server 2020 | Azure DevOps Server 2019 | TFS 2018

Use a pipeline to automatically build and test your .NET Core projects. Learn how to do the following tasks:

Note

For help with .NET Framework projects, see Build ASP.NET apps with .NET Framework.

Note

In Microsoft Team Foundation Server (TFS) 2018 and previous versions, build and release pipelines are called definitions, runs are called builds, service connections are called service endpoints, stages are called environments, and jobs are called phases.

Create your first pipeline

Are you new to Azure Pipelines? If so, then we recommend you try the following section first.

Create a .NET project

If you don't have a .NET project to work with, create a new one, and upload your code to your GitHub repository or Azure Repos. Start by installing the latest .NET 6.0 SDK.

Create a new .NET 6 webapp.

dotnet new webapp -f net6.0

From the same terminal session, run the application locally using the dotnet run command from your project directory.

dotnet run

Upload your code

Upload your code to new webapp GitHub or Azure Repos:

Sign in to Azure Pipelines

Sign-in to Azure Pipelines. After you sign in, your browser goes to https://dev.azure.com/my-organization-name and displays your Azure DevOps dashboard.

Within your selected organization, create a project. If you don't have any projects in your organization, you see a Create a project to get started screen. Otherwise, select the New Project button in the upper-right corner of the dashboard.

Create the pipeline

  1. Sign-in to your Azure DevOps organization and go to your project.

  2. Go to Pipelines, and then select New pipeline.

  3. Do the steps of the wizard by first selecting GitHub as the location of your source code.

  4. You might be redirected to GitHub to sign in. If so, enter your GitHub credentials.

  5. When you see the list of repositories, select your repository.

  6. You might be redirected to GitHub to install the Azure Pipelines app. If so, select Approve & install.

When the Configure tab appears, select ASP.NET Core.

  1. Examine your new pipeline to see what the YAML does. When you're ready, select Save and run.

    Save and run button in a new YAML pipeline

  2. Commit a new azure-pipelines.yml file to your repository. After you're happy with the message, select Save and run again.

    If you want to watch your pipeline in action, select the build job.

    Because your code appeared to be a good match for the ASP.NET Core template, we automatically created the pipeline for you.

    You now have a working YAML pipeline (azure-pipelines.yml) in your repository that's ready for you to customize!

  3. When you're ready to make changes to your pipeline, select it in the Pipelines page, and then Edit the azure-pipelines.yml file.

Read further to learn some of the more common ways to customize your pipeline.

YAML

  1. Add an azure-pipelines.yml file in your repository. Customize the following snippet for your build.
trigger:
- master

pool: Default

variables:
  buildConfiguration: 'Release'

# do this before all your .NET Core tasks
steps:
- task: DotNetCoreInstaller@2
  inputs:
    version: '2.2.402' # replace this value with the version that you need for your project
- script: dotnet build --configuration $(buildConfiguration)
  displayName: 'dotnet build $(buildConfiguration)'
  1. Create a pipeline and select the YAML template.

  2. Set the Agent pool and YAML file path for your pipeline.

  3. Save the pipeline and queue a build. When the Build #nnnnnnnn.n has been queued message appears, select the number link to see your pipeline in action.

  4. When you're ready to make changes to your pipeline, Edit it.

Read further to learn some of the more common ways to customize your pipeline.

Classic

  1. Create a pipeline and select the Empty Pipeline template.

  2. In the task catalog, find and add the .NET Core task. The following task runs dotnet build to build the code in the sample repository.

  3. Save the pipeline and queue a build. When the Build #nnnnnnnn.n has been queued message appears, select the number link to see your pipeline in action.

    You now have a working pipeline that's ready for you to customize!

  4. When you're ready to make changes to your pipeline, Edit it.

Read further to learn some of the more common ways to customize your pipeline.

Build environment

Use Azure Pipelines to build your .NET Core projects. Build your projects on Windows, Linux, or macOS without the need to set up infrastructure. The Microsoft-hosted agents in Azure Pipelines include several preinstalled versions of the .NET Core SDKs.

Ubuntu 18.04 is set here in the YAML file.

pool:
  vmImage: 'ubuntu-18.04' # examples of other options: 'macOS-10.15', 'windows-2019'

See Microsoft-hosted agents for a complete list of images and Pool for further examples.

The Microsoft-hosted agents don't include some of the older versions of the .NET Core SDK. They also don't typically include prerelease versions. If you need these kinds of SDKs on Microsoft-hosted agents, add the UseDotNet@2 task to your YAML file.

To install the preview version of the 5.0.x SDK for building and 3.0.x for running tests that target NET Core 3.0.x, add the following snippet:

steps:
- task: UseDotNet@2
  inputs:
    version: '5.0.x'
    includePreviewVersions: true # Required for preview versions

- task: UseDotNet@2
  inputs:
    version: '3.0.x'
    packageType: runtime

Windows agents already include a .NET Core runtime. To install a newer SDK, set performMultiLevelLookup to true in the following snippet:

steps:
- task: UseDotNet@2
  displayName: 'Install .NET Core SDK'
  inputs:
    version: 5.0.x
    performMultiLevelLookup: true
    includePreviewVersions: true # Required for preview versions

Tip

To save the cost of running the tool installer, you can set up a self-hosted agent. See Linux, macOS, or Windows. You can also use self-hosted agents to save additional time if you have a large repository or you run incremental builds. A self-hosted agent can also help you in using the preview or private SDKs that aren't officially supported by Azure DevOps or you have available on your corporate or on-premises environments only.

You can build your .NET Core projects by using the .NET Core SDK and runtime on Windows, Linux, or macOS. Your builds run on a self-hosted agent. Make sure that you have the necessary version of the .NET Core SDK and runtime installed on the agent.

Restore dependencies

NuGet is a popular way to depend on code that you don't build. You can download NuGet packages and project-specific tools that are specified in the project file by running the dotnet restore command either through the .NET Core task or directly in a script in your pipeline.

You can download NuGet packages from Azure Artifacts, NuGet.org, or some other external or internal NuGet repository. The .NET Core task is especially useful to restore packages from authenticated NuGet feeds.

This pipeline uses an artifact feed for dotnet restore in the .NET Core CLI task.

trigger:
- master

pool:
  vmImage: 'windows-latest'

variables:
  buildConfiguration: 'Release'

steps:
- task: DotNetCoreCLI@2
  inputs:
    command: 'restore'
    feedsToUse: 'select'
    vstsFeed: 'my-vsts-feed' # A series of numbers and letters

- task: DotNetCoreCLI@2
  inputs:
    command: 'build'
    arguments: '--configuration $(buildConfiguration)'
  displayName: 'dotnet build $(buildConfiguration)'

You can download NuGet packages from NuGet.org.

dotnet restore internally uses a version of NuGet.exe that's packaged with the .NET Core SDK. dotnet restore can only restore packages specified in the .NET Core project .csproj files. If you also have a Microsoft .NET Framework project in your solution or use package.json to specify your dependencies, use the NuGet task to restore those dependencies.

In .NET Core SDK version 2.0 and newer, packages get restored automatically when running other commands such as dotnet build.

In .NET Core SDK version 2.0 and newer, packages get restored automatically when running other commands such as dotnet build. However, you might still need to use the .NET Core task to restore packages if you use an authenticated feed.

Your builds may sometimes fail because of connection issues when you restore packages from NuGet.org. You can use Azure Artifacts with upstream sources and cache the packages. The credentials of the pipeline get automatically used when it connects to Azure Artifacts. These credentials are typically derived from the Project Collection Build Service account.

If you want to specify a NuGet repository, put the URLs in a NuGet.config file in your repository. If your feed is authenticated, manage its credentials by creating a NuGet service connection in the Services tab under Project Settings.

If you use Microsoft-hosted agents, you get a new machine every time your run a build, which means restoring the packages every time. Restoration can take a significant amount of time. To mitigate, you can either use Azure Artifacts or a self-hosted agent with the benefit of using the package cache.

To restore packages from an external custom feed, use the following .NET Core task:

# do this before your build tasks
steps:
- task: DotNetCoreCLI@2
  displayName: Restore
  inputs:
    command: restore
    projects: '**/*.csproj'
    feedsToUse: config
    nugetConfigPath: NuGet.config    # Relative to root of the repository
    externalFeedCredentials: <Name of the NuGet service connection>
# ...

For more information about NuGet service connections, see publish to NuGet feeds.

  1. Select Tasks in the pipeline. Select the job that runs your build tasks. Then, select + to add a new task to that job.

  2. In the task catalog, find and add the .NET Core task.

  3. Select the task and, for Command, select restore.

  4. Specify any other options you need for this task. Then save the build.

Note

Make sure the custom feed is specified in your NuGet.config file and that credentials are specified in the NuGet service connection.

Build your project

You build your .NET Core project either by running the dotnet build command in your pipeline or by using the .NET Core task.

To build your project by using the .NET Core task, add the following snippet to your azure-pipelines.yml file:

steps:
- task: DotNetCoreCLI@2
  displayName: Build
  inputs:
    command: build
    projects: '**/*.csproj'
    arguments: '--configuration $(buildConfiguration)' # Update this to match your need

You can run any custom dotnet command in your pipeline. The following example shows how to install and use a .NET global tool, dotnetsay:

steps:
- task: DotNetCoreCLI@2
  displayName: 'Install dotnetsay'
  inputs:
    command: custom
    custom: tool
    arguments: 'install -g dotnetsay'

Build

  1. Select Tasks in the pipeline. Select the job that runs your build tasks. Then select + to add a new task to that job.

  2. In the task catalog, find and add the .NET Core task.

  3. Select the task and, for Command, select build or publish.

  4. Specify any other options you need for this task, and then save the build.

Install a tool

To install a .NET Core global tool like dotnetsay in your build running on Windows, take the following steps:

  1. Add the .NET Core task and set the following properties:

    • Command: custom.
      • Path to projects: leave empty.
    • Custom command: tool.
    • Arguments: install -g dotnetsay.
  2. Add a Command Line task and set the following properties:

    • Script: dotnetsay.

Run your tests

If you have test projects in your repository, then use the .NET Core task to run unit tests by using testing frameworks like MSTest, xUnit, and NUnit.The test project must reference Microsoft.NET.Test.SDK version 15.8.0 or higher. Test results get automatically published to the service. These results are available to you in the build summary and can be used for troubleshooting failed tests and test-timing analysis.

Add the following snippet to your azure-pipelines.yml file:

steps:
# ...
# do this after other tasks such as building
- task: DotNetCoreCLI@2
  inputs:
    command: test
    projects: '**/*Tests/*.csproj'
    arguments: '--configuration $(buildConfiguration)'

An alternative is to run the dotnet test command with a specific logger and then use the Publish Test Results task:

steps:
# ...
# do this after your tests have run
- script: dotnet test <test-project> --logger trx
- task: PublishTestResults@2
  condition: succeededOrFailed()
  inputs:
    testRunner: VSTest
    testResultsFiles: '**/*.trx'

Use the .NET Core task with Command set to test. Path to projects should refer to the test projects in your solution.

Collect code coverage

If you're building on the Windows platform, code coverage metrics can be collected by using the built-in coverage data collector. The test project must reference Microsoft.NET.Test.SDK version 15.8.0 or higher. If you use the .NET Core task to run tests, coverage data is automatically published to the server. The .coverage file can be downloaded from the build summary for viewing in Visual Studio.

Add the following snippet to your azure-pipelines.yml file:

steps:
# ...
# do this after other tasks such as building
- task: DotNetCoreCLI@2
  inputs:
    command: test
    projects: '**/*Tests/*.csproj'
    arguments: '--configuration $(buildConfiguration) --collect "Code coverage"'

If you choose to run the dotnet test command, specify the test results logger and coverage options. Then use the Publish Test Results task:

steps:
# ...
# do this after your tests have run
- script: dotnet test <test-project> --logger trx --collect "Code coverage"
- task: PublishTestResults@2
  inputs:
    testRunner: VSTest
    testResultsFiles: '**/*.trx'
  1. Add the .NET Core task to your build job and set the following properties:

    • Command: test.
    • Path to projects: Should refer to the test projects in your solution.
    • Arguments: --configuration $(BuildConfiguration) --collect "Code coverage".
  2. Ensure that the Publish test results option remains selected.

Collect code coverage metrics with Coverlet

If you're building on Linux or macOS, you can use Coverlet or a similar tool to collect code coverage metrics.

You can publish code coverage results to the server with the Publish Code Coverage Results task. The coverage tool must be configured to generate results in Cobertura or JaCoCo coverage format.

To run tests and publish code coverage with Coverlet, do the following tasks:

  • Add a reference to the coverlet.msbuild NuGet package in your test project(s) for .NET projects below .NET 5. For .NET 5, add a reference to the coverlet.collector NuGet package.
  • Add the following snippet to your azure-pipelines.yml file:
- task: UseDotNet@2
  inputs:
    version: '5.0.x'
    includePreviewVersions: true # Required for preview versions
  
- task: DotNetCoreCLI@2
  displayName: 'dotnet build'
  inputs:
    command: 'build'
    configuration: $(buildConfiguration)
  
- task: DotNetCoreCLI@2
  displayName: 'dotnet test'
  inputs:
    command: 'test'
    arguments: '--configuration $(buildConfiguration) --collect:"XPlat Code Coverage" -- DataCollectionRunSettings.DataCollectors.DataCollector.Configuration.Format=cobertura'
    publishTestResults: true
    projects: 'MyTestLibrary' # update with your test project directory
  
- task: PublishCodeCoverageResults@1
  displayName: 'Publish code coverage report'
  inputs:
    codeCoverageTool: 'Cobertura'
    summaryFileLocation: '$(Agent.TempDirectory)/**/coverage.cobertura.xml'

Package and deliver your code

Upload the build output to Azure Pipelines. You can create and publish a NuGet package, or package the build output into a .zip file to deploy to a web application.

Publish artifacts to Azure Pipelines

To publish the output of your .NET build, do the following tasks:

  • Run dotnet publish --output $(Build.ArtifactStagingDirectory) on CLI or add the DotNetCoreCLI@2 task with publish command.
  • Publish the artifact by using Publish artifact task.

Add the following snippet to your azure-pipelines.yml file:

steps:

- task: DotNetCoreCLI@2
  inputs:
    command: publish
    publishWebProjects: True
    arguments: '--configuration $(BuildConfiguration) --output $(Build.ArtifactStagingDirectory)'
    zipAfterPublish: True

# this code takes all the files in $(Build.ArtifactStagingDirectory) and uploads them as an artifact of your build.
- task: PublishPipelineArtifact@1
  inputs:
    targetPath: '$(Build.ArtifactStagingDirectory)' 
    artifactName: 'myWebsiteName'

Note

The dotNetCoreCLI@2 task has a publishWebProjects input that is set to true by default. This task publishes all web projects in your repo by default. You can find more help and information in the open source task on GitHub.

To copy more files to Build directory before publishing, use Utility: copy files.

Publish to a NuGet feed

To create and publish a NuGet package, add the following snippet:

steps:
# ...
# do this near the end of your pipeline in most cases
- script: dotnet pack /p:PackageVersion=$(version)  # define version variable elsewhere in your pipeline
- task: NuGetAuthenticate@0
  input:
    nuGetServiceConnections: '<Name of the NuGet service connection>'
- task: NuGetCommand@2
  inputs:
    command: push
    nuGetFeedType: external
    publishFeedCredentials: '<Name of the NuGet service connection>'
    versioningScheme: byEnvVar
    versionEnvVar: version

For more information about versioning and publishing NuGet packages, see publish to NuGet feeds.

Deploy a web app

To create a .zip file archive that's ready for publishing to a web app, add the following snippet:

steps:
# ...
# do this after you've built your app, near the end of your pipeline in most cases
# for example, you do this before you deploy to an Azure web app on Windows
- task: DotNetCoreCLI@2
  inputs:
    command: publish
    publishWebProjects: True
    arguments: '--configuration $(BuildConfiguration) --output $(Build.ArtifactStagingDirectory)'
    zipAfterPublish: True

To publish this archive to a web app, see Azure Web Apps deployment.

Publish artifacts to Azure Pipelines

Use the Publish Artifacts task to publish the output of your build to Azure Pipelines.

Publish to a NuGet feed

If you want to publish your code to a NuGet feed, take the following steps:

  1. Use a .NET Core task with Command set to pack.

  2. Publish your package to a NuGet feed.

Deploy a web app

  1. Use a .NET Core task with Command set to publish.

  2. Make sure you've selected the option to create a .zip file archive.

  3. To publish this archive to a web app, see Azure Web Apps deployment.

Build an image and push to container registry

For your app, you can also build an image and push it to a container registry.

Troubleshoot

If you can build your project on your development machine, but you're having trouble building it on Azure Pipelines, explore the following potential causes and corrective actions:

  • We don't install prerelease versions of the .NET Core SDK on Microsoft-hosted agents. After a new version of the .NET Core SDK gets released, it can take a few weeks to roll out to all the Azure Pipelines data centers. You don't have to wait for this rollout to complete. You can use the .NET Core Tool Installer to install the version you want of the .NET Core SDK on Microsoft-hosted agents.
  • Check the .NET Core SDK versions and runtime on your development machine and make sure they match the agent. You can include a command-line script dotnet --version in your pipeline to print the version of the .NET Core SDK. Either use the .NET Core Tool Installer to deploy the same version on the agent, or update your projects and development machine to the newer version of the .NET Core SDK.

  • You might be using some logic in the Visual Studio IDE that isn't encoded in your pipeline. Azure Pipelines runs each of the commands you specify in the tasks one after the other in a new process. Examine the logs from the pipelines build to see the exact commands that ran as part of the build. Repeat the same commands in the same order on your development machine to locate the problem.

  • If you have a mixed solution that includes some .NET Core projects and some .NET Framework projects, you should also use the NuGet task to restore packages specified in packages.config files. Add the MSBuild or Visual Studio Build task to build the .NET Framework projects.

  • Your builds might fail intermittently while restoring packages: either NuGet.org is having issues, or there are networking problems between the Azure data center and NuGet.org. You may want to explore whether using Azure Artifacts with NuGet.org as an upstream source improves the reliability of your builds, as it's not in our control.

  • Occasionally, when we roll out a new version of the .NET Core SDK or Visual Studio, your build might break. For example, if a newer version or feature of the NuGet tool gets shipped with the SDK. To isolate this issue, use the .NET Core Tool Installer task to specify the version of the .NET Core SDK that's used in your build.

FAQ

Q: Where can I learn more about Azure Artifacts and the TFS Package Management service?

A: Package Management in Azure Artifacts

Q: Where can I learn more about .NET Core commands?

A: .NET Core CLI tools

Q: Where can I learn more about running tests in my solution?

A: Unit testing in .NET Core projects

Q: Where can I learn more about tasks?

A: Build and release tasks