Automation with Hashicorp Packer #10: Post Processors

Introduction

This tutorial focuses on utilizing Post-Processors in Hashicorp Packer, a powerful tool for creating custom images across various platforms such as AWS, Azure, GCP, VMware, Docker, Vagrant, and OpenStack. Post-Processors allow you to run tasks after an image is created, enabling you to automate additional processes and enhance your workflow.

Step 1: Understanding Post-Processors

• Post-Processors are plugins in Packer that execute after the image has been built.
• They can perform various tasks, such as:
  • Uploading the image to a specific platform
  • Modifying the image or its metadata
  • Creating a versioned image

Practical Advice

• Familiarize yourself with the different types of Post-Processors available in Packer.
• Review the official Packer documentation for a comprehensive list of Post-Processors you can use.

Step 2: Configuring a Basic Post-Processor

1. Open your Packer template file (usually in JSON or HCL format).
2. Add a post-processors section to your configuration.
3. Define the desired Post-Processor. For example, to upload an AMI to AWS, you might add:

"post-processors": [
  {
    "type": "amazon-ebs",
    "access_key": "{{user `aws_access_key`}}",
    "secret_key": "{{user `aws_secret_key`}}",
    "region": "us-east-1"
  }
]

Practical Advice

• Replace access and secret key placeholders with your actual AWS credentials.
• Ensure you specify a valid region.

Step 3: Running the Packer Build Command

• Once your template is configured with Post-Processors, run the following command in your terminal:

packer build your_template.json

Practical Advice

• Monitor the output for any errors during the build and Post-Processing steps.
• Make sure that your Packer installation is up to date to avoid compatibility issues.

Step 4: Verifying Post-Processor Effects

• After the build completes successfully, verify the results of your Post-Processors:
  • Check if the image was uploaded correctly to the specified platform.
  • Confirm that any modifications made by Post-Processors are as expected.

Common Pitfalls to Avoid

• Ensure that the credentials used in your template have the necessary permissions for the Post-Processor tasks.
• Double-check the syntax in your JSON or HCL files to avoid errors during execution.

Conclusion

Post-Processors in Hashicorp Packer extend the functionality of your image-building process by allowing additional automation steps post-creation. By configuring Post-Processors, you can effectively streamline your workflows and enhance your deployment processes. As next steps, consider exploring more complex Post-Processor configurations or integrating them with CI/CD pipelines to further automate your infrastructure management.