Azure Function - Unable to deploy 502 Bad Gateway

Question

I am trying to deploy a hello world Azure Functions app through Azure Pipeline but it just wont deploy.

I am using azure-functions-core-tools v4.x which allows me to create a function app using func init and func new ...

Now the folder structure I got is this:

root
host.json
node_modules
package.json
src/function/helloWorld.js <-- JUST A SIMPLE HELLO WORLD FUNCTION

const { app } = require('@azure/functions');

app.http('helloWorld', {
    methods: ['GET', 'POST'],
    authLevel: 'anonymous',
    handler: async (request, context) => {
        context.log(`Http function processed request for url "${request.url}"`);

        const name = request.query.get('name') || await request.text() || 'world';

        return { body: `Hello, ${name}!` };
    }
});

have host.json at root.

My pipeline looks like this:

steps:
  - task: UseNode@1
    inputs:
      version: $(nodeVersion)

  - task: Npm@1
    displayName: "Install dependencies"
    inputs:
      command: "install"

  - task: ArchiveFiles@2
    displayName: "Archive function app"
    inputs:
      rootFolderOrFile: "$(System.DefaultWorkingDirectory)" # <-- zip entire project
      includeRootFolder: false
      archiveType: "zip"
      archiveFile: "$(Build.ArtifactStagingDirectory)/functionapp.zip"
      replaceExistingArchive: true

  - task: PublishBuildArtifacts@1
    displayName: "Publish function app artifact"
    inputs:
      PathtoPublish: "$(Build.ArtifactStagingDirectory)"
      ArtifactName: "functionapp"

  - task: AzureFunctionApp@1
    displayName: "Deploy to Azure Function App"
    inputs:
      azureSubscription: $(azureServiceConnection)
      appType: functionAppLinux
      appName: $(functionAppName)
      package: "$(Build.ArtifactStagingDirectory)/functionapp.zip"

I am getting error:

App Service Application settings are already present. Package deployment using ZIP Deploy initiated. ##[error]Failed to deploy web package to App Service. ##[warning]Can't find loc string for key: KuduStackTraceURL ##[error]KuduStackTraceURL [REDACTED - DOESNT OPEN IN BROWSER ANYWAY] ##[error]Error: Error: Failed to deploy web package to App Service. Bad Gateway (CODE: 502) ##[warning]Error: Failed to update deployment history. Error: Method Not Allowed (CODE: 405) App Service Application URL: [REDACTED] Finishing: Deploy to Azure Function App

I have confirmed that Artifact is being built. All other steps in pipeline are running fine but I DONT KNOW WHY this step is not working.

As per GPT, its a folder structure issue. I got this folder structure from azure-functions-core-tools package.

Did you try deploying the function code using any other IDE or cli? — Pravallika KV
– Pravallika KV, Commented May 9 at 12:47

Pravallika KV · Accepted Answer · 2025-05-09 13:56:02Z

Set the deploy task to AzureFunctionApp@2 in the pipeline:

deploy:
          steps:
          - task: AzureFunctionApp@2

I have used below yml code to Build and deploy the Node Js function to Azure using devops pipeline.

Pipeline:

trigger:
- master

variables:

  azureSubscription: 'f94XXXded364'
 
  # Function app name
  functionAppName: 'appname'

  # Environment name
  environmentName: 'environmentname'

  # Agent VM image name
  vmImageName: 'ubuntu-latest'

stages:
- stage: Build
  displayName: Build stage
  jobs:
  - job: Build
    displayName: Build
    pool:
      vmImage: $(vmImageName)

    steps:
    - task: NodeTool@0
      inputs:
        versionSpec: '20.x'
      displayName: 'Install Node.js'

    - script: |
        if [ -f extensions.csproj ]
        then
            dotnet build extensions.csproj --runtime ubuntu.16.04-x64 --output ./bin
        fi
      displayName: 'Build extensions'

    - script: |
        npm install
        npm run build --if-present
        npm run test --if-present
      displayName: 'Prepare binaries'

    - task: ArchiveFiles@2
      displayName: 'Archive files'
      inputs:
        rootFolderOrFile: '$(System.DefaultWorkingDirectory)'
        includeRootFolder: false
        archiveType: zip
        archiveFile: $(Build.ArtifactStagingDirectory)/$(Build.BuildId).zip
        replaceExistingArchive: true

    - upload: $(Build.ArtifactStagingDirectory)/$(Build.BuildId).zip
      artifact: drop

- stage: Deploy
  displayName: Deploy stage
  dependsOn: Build
  condition: succeeded()
  jobs:
  - deployment: Deploy
    displayName: Deploy
    environment: $(environmentName)
    pool:
      vmImage: $(vmImageName)
    strategy:
      runOnce:
        deploy:
          steps:
          - task: AzureFunctionApp@2
            inputs:
              connectedServiceNameARM: '$(azureSubscription)'
              appType: 'functionAppLinux'
              appName: $(functionAppName)
              deployToSlotOrASE: true
              package: '$(Pipeline.Workspace)/drop/$(Build.BuildId).zip'
              runtimeStack: 'NODE|20'
              deploymentMethod: 'auto'

Code snippet:

const { app } = require('@azure/functions');

app.http('httpTrigger', {
    methods: ['GET', 'POST'],
    authLevel: 'anonymous',
    handler: async (request, context) => {
        context.log(`Http function processed request for url "${request.url}"`);

        const name = request.query.get('name') || await request.text() || 'world';

        return { body: `Hello, ${name}!` };
    }
});

Able to build and deploy the function successfully:

Portal:

I had already solved it. I was using @1 version of task. Instead I needed to use @2 version. Thanks

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