Setting up a simple Azure DevOps Pipeline

Migrating from GitHub Actions to Azure DevOps Pipelines for .NET Deployment  

Recently, I transitioned my .NET Core API deployment from GitHub Actions to Azure DevOps Pipelines. While the process seemed straightforward at first, I ran into a few challenges—particularly around self-hosted agents, deployment methods, and ensuring my API was properly updated.  

In this post, I’ll walk through the migration steps, issues I encountered, and how I resolved them.

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1. Setting Up Azure DevOps Pipelines  

Parallellism Request & Self-Hosted Agent  

When I first set up my pipeline, Microsoft required approval for parallelism to run the pipeline on their hosted agents. This request can take up to 5 business days to process.

In the meantime, they suggested using a self-hosted agent to proceed with deployments immediately.

To set up a self-hosted agent:

1. In Azure DevOps, go to Organization Settings → Agent Pools

2. Create a new agent pool

3. Add a new agent and download the provided ZIP

4. Follow the setup instructions to register and start the agent

Once the agent was up and running, I was able to successfully trigger my first deployment.

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2. Deployment Issues & Fixes  

Initial Deployment – 500 Errors  

Although the first deployment succeeded, my API returned 500 errors when accessed. Checking via FTP, I noticed that my .dll files were not updated—meaning the new code wasn’t actually deployed!  

Root Cause: Wrong Deployment Method  

Comparing my GitHub Actions workflow with the Azure DevOps YAML pipeline, I noticed a key difference:

• GitHub Actions was using zipDeploy, which properly extracted and deployed the app.

• Azure DevOps, by default, was running in Run-From-Zip mode, meaning my app was running from a mounted ZIP file and not updating as expected.

Fix: Explicitly Use zipDeploy  

To resolve this, I added the following line to my Azure DevOps pipeline:

deploymentMethod: 'zipDeploy'

This ensured that Azure properly extracted the contents of the deployment package instead of running it directly from a ZIP file.

3. Comparing GitHub Actions vs. Azure DevOps YAML

Here’s a side-by-side comparison of my GitHub Actions workflow and the Azure DevOps pipeline YAML:

GitHub Actions Workflow (Previously Working)

name: Build and Deploy .NET API to Azure

on:
  push:
    branches:
      - main

jobs:
  build:
    runs-on: windows-latest
    steps:
      - uses: actions/checkout@v4
      - name: Set up .NET Core
        uses: actions/setup-dotnet@v1
        with:
          dotnet-version: '8.x'
          include-prerelease: true
      - name: Build and Publish
        run: |
          dotnet build --configuration Release
          dotnet publish -c Release -o $/myapp
      - name: Upload Artifact
        uses: actions/upload-artifact@v4
        with:
          name: .net-app
          path: $/myapp

  deploy:
    runs-on: windows-latest
    needs: build
    steps:
      - name: Download Artifact
        uses: actions/download-artifact@v4
        with:
          name: .net-app
      - name: Deploy to Azure
        uses: azure/webapps-deploy@v2
        with:
          app-name: 'FoodDiary'
          publish-profile: $
          package: .

Azure DevOps Pipeline (Initial Version - Not Working Correctly)

stages:
- stage: Build
  jobs:
  - job: Build
    steps:
    - checkout: self
    - task: UseDotNet@2
      inputs:
        packageType: 'sdk'
        version: '8.x'
        includePreviewVersions: true
    - script: dotnet build --configuration Release
      displayName: 'Build .NET'
    - script: dotnet publish -c Release -o $(Build.ArtifactStagingDirectory)/myapp
      displayName: 'dotnet publish'
    - task: PublishBuildArtifacts@1
      inputs:
        pathToPublish: '$(Build.ArtifactStagingDirectory)/myapp'
        artifactName: 'drop'

- stage: Deploy
  jobs:
  - job: Deploy
    steps:
    - task: DownloadBuildArtifacts@0
      inputs:
        buildType: 'current'
        artifactName: 'drop'
        downloadPath: '$(System.ArtifactsDirectory)'
    - task: AzureWebApp@1
      inputs:
        appType: webApp
        azureSubscription: '$(azSub)'
        appName: 'FoodDiary'
        package: '$(System.ArtifactsDirectory)/drop'

Azure DevOps Pipeline (Fixed Version - Now Working)

- task: AzureWebApp@1
  inputs:
    appType: webApp
    azureSubscription: '$(azSub)'
    appName: 'FoodDiary'
    package: '$(System.ArtifactsDirectory)/drop'
    deploymentMethod: 'zipDeploy'