How to Create, Configure, and Manage a Self-Hosted Agent in Azure DevOps

In the intricate realm of DevOps, flexibility and granular control over your build and deployment processes are essential. While Azure DevOps offers robust cloud-hosted agents, there are scenarios where self-hosted agents become indispensable. Whether it’s for specific tool integrations, customized configurations, or compliance with stringent security policies, self-hosted agents provide the ultimate control. This guide will walk you through setting up a self-hosted agent in Azure DevOps, enriched with best practices, detailed steps, and management tips.

Prerequisites

Before diving in, ensure you have the following prerequisites:

1. Azure DevOps Account: Create one at Azure DevOps if you haven’t already.
2. Agent Machine: A physical or virtual machine running Windows, macOS, or Linux.
3. Network and Permissions: Ensure the machine has internet access and administrative permissions to install software.

Step 1: Create a Personal Access Token (PAT)

To authenticate your self-hosted agent with Azure DevOps, you need a Personal Access Token (PAT).

1. Navigate to your Azure DevOps organization settings.
2. Select "Personal Access Tokens" under the "Security" tab.
3. Click on "New Token".
4. Set the appropriate scopes (e.g., Agent Pools (read, manage)) and create the token.
5. Copy the token and store it securely.

Step 2: Download the Agent Package

On your agent machine:

1. Navigate to your Azure DevOps project.
2. Go to Project Settings > Agent pools.
3. Select the desired agent pool or create a new one.
4. Click on New Agent.
5. Download the appropriate agent package for your operating system.

Step 3: Configure the Agent

On Windows:

1. Extract the downloaded zip file.
2. Open Command Prompt and navigate to the extracted directory.
3. Run config.cmd.
4. Provide the server URL (e.g., https://dev.azure.com/yourorganization).
5. Paste the PAT when prompted.
6. Configure the agent with the default options or customize as needed.
7. Run the agent by executing run.cmd.

On Linux:

1. Download the file
   

   wget https://vstsagentpackage.azureedge.net/agent/3.239.1/vsts-agent-osx-x64-3.239.1.tar.gz
   

2. Extract the downloaded tar.gz file:
   

   tar zxvf vsts-agent-linux-x64-*.tar.gz
   

3. Navigate to the extracted directory:
   

   cd vsts-agent-linux-x64
   

4. Run the configuration script:
   

   ./config.sh
   

5. Provide the server URL and PAT when prompted.

6. Configure the agent, then start it:
   

   ./svc.sh install
   ./svc.sh start
   

On macOS:

1. Extract the downloaded tar.gz file:
   

   tar zxvf vsts-agent-osx-x64-*.tar.gz
   
   

2. Navigate to the extracted directory:
   

   cd vsts-agent-osx-x64
   
   

3. Run the configuration script:
   

   ./config.sh
   
   

4. Provide the server URL and PAT when prompted.

5. Configure the agent, then start it:
   

   ./svc.sh install
   ./svc.sh start
   
   

Step 4: Verify Agent Configuration

Back in Azure DevOps:

1. Navigate to "Project Settings" > "Agent Pools".
2. Select your pool and check if the new agent is listed and online.

Managing the Agent

Removing the Agent

If you need to remove the agent from your pool:

1. Stop the Agent:
   • On Windows: Run svc.sh stop or manually stop the service from the Services app.
   • On Linux/macOS: Run ./svc.sh stop.
2. Unconfigure the Agent:
   • Navigate to the agent's directory and run the unconfiguration command:
     • On Windows: config.cmd remove
     • On Linux/macOS: ./config.sh remove
3. Delete the Agent Directory:
   • Once unconfigured, you can safely delete the agent's directory to free up space.

Reconfiguring the Agent

To reconfigure an existing agent:

1. Navigate to the Agent Directory:
   • If you haven’t deleted the agent directory, navigate back to it.
2. Run the Configuration Command:
   • On Windows: config.cmd
   • On Linux/macOS: ./config.sh
3. Follow the Configuration Steps:
   • Provide the server URL and PAT when prompted.
   • Customize the agent settings as needed.
4. Start the Agent:
   • On Windows: Run run.cmd or start the service from the Services app.
   • On Linux/macOS: Run ./svc.sh start.

Best Practices

1. Security: Regularly rotate your PATs and ensure they have the least privilege necessary.
2. Maintenance: Keep the agent machine updated with the latest security patches and software updates.
3. Scalability: For large teams or complex pipelines, consider setting up multiple agents to distribute the workload.
4. Monitoring: Utilize Azure Monitor or other monitoring tools to keep an eye on the health and performance of your self-hosted agents.

Conclusion

Setting up, configuring, and managing a self-hosted agent in Azure DevOps empowers you with greater control and customization of your CI/CD pipelines. It’s a straightforward process that opens up a world of possibilities for optimizing your development workflow. Whether you're integrating specific tools, enhancing security, or boosting performance, a self-hosted agent is a powerful addition to your DevOps toolkit.

Happy DevOps-ing!