Build Python apps

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You can use Azure Pipelines to build, test, and deploy Python apps and scripts as part of your CI/CD system. This article focuses on creating a basic pipeline.

If you want an end-to-end tutorial, see Use CI/CD to deploy a Python web app to Azure App Service on Linux.

To create and activate an Anaconda environment and install Anaconda packages with conda, see Run pipelines with Anaconda environments.

Create your first pipeline

New to Azure Pipelines? If so, then we recommend you try this section before moving on to other sections.

Get the code

Import this repo into your Git repo in Azure DevOps Server 2019:

Import this repo into your Git repo:

https://github.com/Microsoft/python-sample-vscode-flask-tutorial

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 Python package to create a Python package to test on multiple Python versions.

1. When your new pipeline appears, take a look at the YAML to see what it does. When you're ready, select Save and run.

   

2. You're prompted to 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.

   You just ran a pipeline that we automatically created for you, because your code appeared to be a good match for the Python package template.

   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 this snippet for your build.

trigger:
- master

pool: Default

steps:
- script: python -m pip install --upgrade pip
  displayName: 'Install dependencies'

- script: pip install -r requirements.txt
  displayName: 'Install requirements'

2. Create a pipeline (if you don't know how, see Create your first pipeline), and for the template select YAML.

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

4. 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.

5. 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

You don't have to set up anything for Azure Pipelines to build Python projects. Python is preinstalled on Microsoft-hosted build agents for Linux, macOS, or Windows. To see which Python versions are preinstalled, see Use a Microsoft-hosted agent.

Use a specific Python version

To use a specific version of Python in your pipeline, add the Use Python Version task to azure-pipelines.yml. This snippet sets the pipeline to use Python 3.6:

steps:
- task: UsePythonVersion@0
  inputs:
    versionSpec: '3.6'

Use multiple Python versions

To run a pipeline with multiple Python versions, for example to test a package against those versions, define a job with a matrix of Python versions. Then set the UsePythonVersion task to reference the matrix variable.

jobs:
- job: 'Test'
  pool:
    vmImage: 'ubuntu-latest' # other options: 'macOS-latest', 'windows-latest'
  strategy:
    matrix:
      Python27:
        python.version: '2.7'
      Python35:
        python.version: '3.5'
      Python36:
        python.version: '3.6'

  steps:
  - task: UsePythonVersion@0
    inputs:
      versionSpec: '$(python.version)'

You can add tasks to run using each Python version in the matrix.

Run Python scripts

To run Python scripts in your repository, use a script element and specify a filename. For example:

- script: python src/example.py

You can also run inline Python scripts with the Python Script task:

- task: PythonScript@0
  inputs:
    scriptSource: 'inline'
    script: |
      print('Hello world 1')
      print('Hello world 2')

To parameterize script execution, use the PythonScript task with arguments values to pass arguments into the executing process. You can use sys.argv or the more sophisticated argparse library to parse the arguments.

- task: PythonScript@0
  inputs:
    scriptSource: inline
    script: |
      import sys
      print ('Executing script file is:', str(sys.argv[0]))
      print ('The arguments are:', str(sys.argv))
      import argparse
      parser = argparse.ArgumentParser()
      parser.add_argument("--world", help="Provide the name of the world to greet.")
      args = parser.parse_args()
      print ('Hello ', args.world)
    arguments: --world Venus

Install dependencies

You can use scripts to install specific PyPI packages with pip. For example, this YAML installs or upgrades pip and the setuptools and wheel packages.

- script: python -m pip install --upgrade pip setuptools wheel
  displayName: 'Install tools'

Install requirements

After you update pip and friends, a typical next step is to install dependencies from requirements.txt:

- script: pip install -r requirements.txt
  displayName: 'Install requirements'

Run tests

Use scripts to install and run various tests in your pipeline.

Run lint tests with flake8

To install or upgrade flake8 and use it to run lint tests, use this YAML:

- script: |
    python -m pip install flake8
    flake8 .
  displayName: 'Run lint tests'

Test with pytest and collect coverage metrics with pytest-cov

Use this YAML to install pytest and pytest-cov, run tests, output test results in JUnit format, and output code coverage results in Cobertura XML format:

- script: |
    pip install pytest pytest-azurepipelines
    pip install pytest-cov
    pytest --doctest-modules --junitxml=junit/test-results.xml --cov=. --cov-report=xml
  displayName: 'pytest'

Run tests with Tox

Azure Pipelines can run parallel Tox test jobs to split up the work. On a development computer, you have to run your test environments in series. This sample uses tox -e py to run whichever version of Python is active for the current job.

- job:

  pool:
    vmImage: 'ubuntu-latest'
  strategy:
    matrix:
      Python27:
        python.version: '2.7'
      Python35:
        python.version: '3.5'
      Python36:
        python.version: '3.6'
      Python37:
        python.version: '3.7'

  steps:
  - task: UsePythonVersion@0
    displayName: 'Use Python $(python.version)'
    inputs:
      versionSpec: '$(python.version)'

  - script: pip install tox
    displayName: 'Install Tox'

  - script: tox -e py
    displayName: 'Run Tox'

Publish test results

Add the Publish Test Results task to publish JUnit or xUnit test results to the server:

- task: PublishTestResults@2
  condition: succeededOrFailed()
  inputs:
    testResultsFiles: '**/test-*.xml'
    testRunTitle: 'Publish test results for Python $(python.version)'

Publish code coverage results

Add the Publish Code Coverage Results task to publish code coverage results to the server. You can see coverage metrics in the build summary and download HTML reports for further analysis.

- task: PublishCodeCoverageResults@1
  inputs:
    codeCoverageTool: Cobertura
    summaryFileLocation: '$(System.DefaultWorkingDirectory)/**/coverage.xml'

Package and deliver code

To authenticate with twine, use the Twine Authenticate task to store authentication credentials in the PYPIRC_PATH environment variable.

- task: TwineAuthenticate@0
  inputs:
    artifactFeed: '<Azure Artifacts feed name>'
    pythonUploadServiceConnection: '<twine service connection from external organization>'

Then, add a custom script that uses twine to publish your packages.

- script: |
   twine upload -r "<feed or service connection name>" --config-file $(PYPIRC_PATH) <package path/files>

You can also use Azure Pipelines to build an image for your Python app and push it to a container registry.

Related extensions

• Azure DevOps plugin for PyCharm (IntelliJ) (Microsoft)
• Python in Visual Studio Code (Microsoft)