Deploying Go applications to App Service Linux with Azure DevOps pipelines

7 minute read | By Anthony Salemo

This post will cover deploying Go applications to Azure App Service Linux with Go “Blessed” images using Azure DevOps pipelines.

Overview

Note: Go “Blessed Images” are currently marked as experimental - these images and behavior on App Service are subject to change. This is also not recommended for production.

Prerequisites

Application Logs

IMPORTANT: Ensure that App Service Logs are enabled - review this document on how to do so.

This is important incase the application crashes due to misconfiguration of any of these profilers - given this is all at the application level, we need these logs enabled to see what may have gone wrong. You can view logging in a few ways:

Diagnose and Solve Problems -> Application Logs
Log Stream
Directly through the Kudu site - such as the /newui endpoint (https://sitename.scm.azurewebsites.net/newui) or the normal Kudu site
An FTP client to view logfiles under /home/LogFiles

Azure DevOps organization

A new or existing Azure DevOps Organization and a DevOps project is needed.

Quickstart

Go “Blessed Images” expose port 8080 - which Go application HTTP servers should be listening on. For example:

err := http.ListenAndServe(":8080", nil)

You can however change this with the PORT App Setting - the HTTP listening port in the application would need to be updated.

If you wanted to listen for PORT, you could do the following:

port := ":" + os.Getenv("PORT")
log.Fatal(app.Listen(port))

See: Default exposed ports of Azure App Service Linux Blessed Images

For this example, we’re going to be using the Fiber example from here azureossd - go-devops-examples. You can bring your own code as well.

Local development

We can quickly get started with a Go project using Fiber with the following:

Create a main.go file
Create a go.mod file by running go mod init yourmodulename
Install Fiber with go get github.com/gofiber/fiber/v2
In the main.go file, add the following:

package main

import (
    "log"

    "github.com/gofiber/fiber/v2"
)

func main() {
    app := fiber.New()

    app.Get("/", func (c *fiber.Ctx) error {
        return c.SendString("Hello, World - From Fiber!")
    })

  log.Fatal(app.Listen(":8080"))
}

Run the application with go run ., you should now see the below in your terminal:

$ go run .

 ┌───────────────────────────────────────────────────┐
 │                   Fiber v2.48.0                   │
 │               http://127.0.0.1:8080               │
 │       (bound on host 0.0.0.0 and port 8080)       │
 │ Handlers ............. 2  Processes ........... 1 │
 │ Prefork ....... Disabled  PID ............. 24812 │
 └───────────────────────────────────────────────────┘

You should now be able to access the application over localhost:8080

Create an App Service

Follow this documentation on creating a Go 1.19 App Service on Linux - Deploy a Go web app to Azure App Service

Create the pipeline

Note: This assumes your Azure DevOps organization is already created

Now we’ll create the pipeline.

In your Azure DevOps organization - create a DevOps project, if not already created yet. Choose a Project name and Visibility and then click Create project

DevOps project

On the next page, it will ask (if using a newly created project) where your code is hosted. Choose the option relevant to you.

Repo location

Select your repository that contains your Go source code.
The next page is “Configure our pipeline” - select Starter pipeline.

Note: Unline Java, Python and Node - there is no starter template available to deploy to Web Apps

Starter pipeline

Your starter pipeline will have the following:

trigger:
- main

pool:
  vmImage: ubuntu-latest

steps:
- script: echo Hello, world!
  displayName: 'Run a one-line script'

- script: |
    echo Add other tasks to build, test, and deploy your project.
    echo See https://aka.ms/yaml
  displayName: 'Run a multi-line script'

Let’s change this step-by-step:

a. Add a variables property at the top of the file:

 variables:
   webAppName: 'myapp'

b. Add a stages property and stage for “Build”:

 stages:
 - stage: Build
 displayName: Build stage
 jobs:
 - job: BuildJob
     steps:
     - task: GoTool@0
       inputs:
         version: '1.19'
            
     - task: Go@0
       inputs:
         command: custom
         customCommand: 'mod'
         arguments: 'tidy'
         workingDirectory: '$(System.DefaultWorkingDirectory)'
       displayName: 'Go mod tidy'

     - task: Go@0
       inputs:
         command: 'build'
         workingDirectory: '$(System.DefaultWorkingDirectory)'
       displayName: 'Go build'

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

     - task: PublishBuildArtifacts@1
       inputs:
         artifactName: drop

What did we do?:
- We used the Go@0 to run go mod tidy to download all our dependencies required in go.mod
- We use Go@0 to build the application and generate an executable
- We then zip up the executable with ArchiveFiles@2 to be passed on to the deploy stage

Now, add a deploy stage, we’ll do this in two parts:

First, add the stage without the task:

- stage: Deploy
  displayName: 'Deploy Web App'
  dependsOn: Build
  condition: succeeded()
  jobs:
  - deployment: DeploymentJob
    environment: $(webAppName)
    strategy:
      runOnce:
        deploy:
          steps:

Next, click Pipelines -> Edit:
Open the “Task Assistant” on the top right - if it’s not already opened.
Search for “deploy” in the search bar for avaialble built-in Azure DevOps tasks. You can use either the Azure App Service deploy or Azure Web App task to deploy to “Blessed” images on App Service Linux.
For this example, we’ll be using the Azure App Service deploy (AzureRmWebAppDeployment@4) task. Fill out the following information:
- Connection type: Your connection/authentication method
- Azure subscription: Your subscription in which the App Service resides
- App Service type: Choose “Web App on Linux”
- App Service name: Name of the App Service
- Package or folder: Set this to $(Pipeline.Workspace)/drop/$(Build.BuildId).zip
- Runtime Stack: Set this to GO|1.19
The full deploy stage will now look like:

- stage: Deploy
  displayName: 'Deploy Web App'
  dependsOn: Build
  condition: succeeded()
  jobs:
  - deployment: DeploymentJob
    environment: $(webAppName)
    strategy:
      runOnce:
        deploy:
          steps: 
          - task: AzureRmWebAppDeployment@4
            inputs:
              ConnectionType: 'AzureRM'
              azureSubscription: 'your-connection'
              appType: 'webAppLinux'
              WebAppName: 'your-site'
              packageForLinux: '$(Pipeline.Workspace)/drop/$(Build.BuildId).zip'
              RuntimeStack: 'GO|1.19'

The full runnable azure-pipelines.yml will look like this:

# Starter pipeline
# Start with a minimal pipeline that you can customize to build and deploy your code.
# Add steps that build, run tests, deploy, and more:
# https://aka.ms/yaml

trigger:
- main

variables:
  webAppName: 'your-site'

pool:
  vmImage: ubuntu-latest

stages:
- stage: Build
  displayName: Build stage
  jobs:
  - job: BuildJob
    steps:
    - task: GoTool@0
      inputs:
          version: '1.19'
        
    - task: Go@0
      inputs:
          command: custom
          customCommand: 'mod'
          arguments: 'tidy'
          workingDirectory: '$(System.DefaultWorkingDirectory)/fiber'
      displayName: 'Go mod tidy'

    - task: Go@0
      inputs:
        command: 'build'
        workingDirectory: '$(System.DefaultWorkingDirectory)/fiber'
      displayName: 'Go build'

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

    - task: PublishBuildArtifacts@1
      inputs:
        artifactName: drop
        
- stage: Deploy
  displayName: 'Deploy Web App'
  dependsOn: Build
  condition: succeeded()
  jobs:
  - deployment: DeploymentJob
    environment: $(webAppName)
    strategy:
      runOnce:
        deploy:
          steps: 
          - task: AzureRmWebAppDeployment@4
            inputs:
              ConnectionType: 'AzureRM'
              azureSubscription: 'your-connection'
              appType: 'webAppLinux'
              WebAppName: 'your-site'
              packageForLinux: '$(Pipeline.Workspace)/drop/$(Build.BuildId).zip'
              RuntimeStack: 'GO|1.19'

Important notes

In the go build section, we don’t specify anything like -o, for any named execuable output.

This is because, at the current time, SCM_DO_BUILD_DURING_DEPLOYMENT is not honored on Go “Blessed” images. oryxBuilder will always be the builder used.

The executable is built by Oryx - and named oryxBuildBinary and placed in /home/site/wwwroot.

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Deploying Go applications to App Service Linux with Azure DevOps pipelines

Overview

Prerequisites

Application Logs

Azure DevOps organization

Quickstart

Local development

Create an App Service

Create the pipeline

Important notes

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