Automation with Hashicorp Packer #6: Configuring Provisioners

Introduction

This tutorial focuses on configuring provisioners in Hashicorp Packer, a powerful tool for automating the creation of custom machine images across various platforms like AWS, Azure, and Google Cloud. By the end of this guide, you will understand how to effectively use provisioners to customize your images, enhancing your automation workflow.

Step 1: Understanding Provisioners

Provisioners are components in Packer that allow you to install and configure software on your image after it has been created. This step is crucial for setting up your environment according to your specifications.

• Common Provisioner Types:
  • Shell: Executes shell scripts on the image.
  • Ansible: Uses Ansible playbooks to configure the image.
  • Puppet: Applies Puppet manifests for configuration.
  • Chef: Utilizes Chef cookbooks for setup.
  • File: Uploads files to the image.

Step 2: Setting Up Your Packer Template

Before you can use provisioners, you need a basic Packer template. This template defines how your image will be built.

• Create a JSON or HCL file:
  • Define the builders, which specify the type of image you want to create.
  • Example of a simple builder configuration:

    {
      "builders": [
        {
          "type": "amazon-ebs",
          "access_key": "YOUR_ACCESS_KEY",
          "secret_key": "YOUR_SECRET_KEY",
          "region": "us-east-1",
          "source_ami": "ami-123456",
          "instance_type": "t2.micro",
          "ssh_username": "ec2-user",
          "ami_name": "MyCustomImage {{timestamp}}"
        }
      ]
    }
    

Step 3: Adding Provisioners to Your Template

Now that you have a basic template, you can add provisioners to configure your image.

• Add Provisioners Section:
  • Include a provisioners section in your template.
  • Example of adding a shell provisioner:

    {
      "provisioners": [
        {
          "type": "shell",
          "inline": [
            "sudo yum update -y",
            "sudo yum install -y httpd",
            "sudo systemctl start httpd",
            "sudo systemctl enable httpd"
          ]
        }
      ]
    }
    

Step 4: Running the Packer Build

With your template configured, you can now execute the build process.

• Use the Packer Build Command:
  • Run the following command in your terminal:

    packer build your-template.json
    

  • Monitor the output for any errors during the provisioning process.

Step 5: Verifying Your Image

After the build process is complete, it's essential to verify that your image has been configured correctly.

• Check the Image:
  • Log into the created instance using SSH.
  • Ensure that the installed software and configurations are as expected.

Conclusion

In this tutorial, you learned how to configure provisioners in Hashicorp Packer to customize your machine images. By understanding provisioners and executing a proper build process, you can streamline your automation tasks significantly. For further exploration, consider experimenting with different provisioner types and configurations to enhance your image creation process.