Let us learn how to configure a self-hosted agent using Docker in Azure DevOps pipelines.
What is an Agent?
An agent is computing infrastructure with installed agent software that runs one job at a time.To build your code or deploy your software using Azure Pipelines, you need at least one agent. As you add more code and people, you'll eventually need more.
When your pipeline runs, the system begins one or more jobs.
In Azure pipelines, there are two types of build agents:
- Microsoft-hosted agents - This is a service totally managed by Microsoft and it's cleared on every execution of the pipeline (on each pipeline execution, you have a fresh new environment).
- Self-hosted agents - This is a service that you can to set up and manage by yourself. This can be a custom virtual machine on Azure or a custom on-premise machine inside your infrastructure. In a self-hosted agent, you can install all the software you need for your builds, and this is persisted on every pipeline execution. A self-hosted agent can be on Windows, Linux, macOS, or in a Docker container.
You can set up a self-hosted agent in Azure Pipelines to run inside a Windows Server Core (for Windows hosts), or Ubuntu container (for Linux hosts) with Docker. We will learn in this article on how to host Ubuntu Docker container on Linux machines.
Pre-requisites:
- Microsoft account setup
- Azure account and subscription setup
- Create a VM(Ubuntu 20.0.4) in Azure Cloud
- Create Personal Access Token in Azure DevOps
- Dockerfile created for docker build agent, please refer this repo
How to configure Self-hosted docker build agent?
1. Go to Azure DevOps dashboard - https://dev.azure.com/
2. Select your project dashboard
3. Go to your project settings
Make sure you select Grant access permission to all pipelines
Login to Azure VM where the docker build agents will be running.
Step #1 - Install Docker CLI so we can build docker image
sudo apt update && sudo apt install docker.io -y
Step #2 - Add logged in user to docker group
sudo usermod -a -G docker $USER
Step #3 - Clone repo which has Dockerfile
git clone https://github.com/akannan1087/ado-docker-agent-repo.git
Sample dockerfile is here.. please feel free to add any software in the docker agent.
FROM ubuntu:22.04
RUN apt update -y && apt upgrade -y && apt install curl git jq libicu70 maven -y
# Also can be "linux-arm", "linux-arm64".
ENV TARGETARCH="linux-x64"
WORKDIR /azp/
COPY ./start.sh ./
RUN chmod +x ./start.sh
# Create agent user and set up home directory
RUN useradd -m -d /home/agent agent
RUN chown -R agent:agent /azp /home/agent
USER agent
# Another option is to run the agent as root.
# ENV AGENT_ALLOW_RUNASROOT="true"
ENTRYPOINT ./start.sh
Step #4 - change directory
cd ado-docker-agent-repo/azp-agent-in-docker/
Step #5 - Build the Docker image
sudo docker build --tag "azp-agent:linux" --file Dockerfile .
Step #6: Run the agent as a container
Run the below command:
sudo docker run -e AZP_URL="https://dev.azure.com/your_org_name" -e AZP_TOKEN="XXXX" -e AZP_POOL=myAgentPool -e AZP_AGENT_NAME="myLinuxDockerBuildAgent" --name "azp-agent" azp-agent:linux
that's it, docker agent is successfully started.
Step #7: Verify if docker agent is running or not
Run the below command:
sudo docker ps
Check the status of build Agent
Click on agentPool name, click on Agents
This confirms that Build agent is successfully configured in Azure DevOps and is available to run builds.
How to use the Docker build agent in your pipelines?
Please use the docker agent in the classic pipeline like below: select the agentPool
run the job. now you can see the jobs under myAgentPool--> Jobs
trigger:
- main
pool:
name: myAgentPool
stages:
- stage: Build
displayName: Build stage
jobs:
- job: MavenPackageAndPublishArtifacts
displayName: Maven Package and Publish Artifacts
steps:
- task: Maven@3
displayName: 'Maven Package'
inputs:
mavenPomFile: 'MyWebApp/pom.xml'
References:
Watch steps in YouTube channel:
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