Automation with Hashicorp Packer #1: Intro mutable vs Immutable infrastructure

Introduction

This tutorial is designed to introduce you to the concepts of mutable and immutable infrastructure, which are fundamental to understanding how Hashicorp Packer operates. Packer is a powerful tool that simplifies the process of creating custom machine images across multiple platforms. By grasping the differences between these two types of infrastructure, you will gain insight into the benefits of using Packer for your automation needs.

Step 1: Understand Mutable Infrastructure

Mutable infrastructure refers to the traditional approach where servers are modified and updated in place. This means:

• Updates and Changes: Changes are made directly to the existing servers. For example, applying patches or installing software updates.
• Potential Risks: This approach can lead to configuration drift, where the server’s state diverges from its intended configuration over time.
• Rollback Complexity: Rolling back updates can be complicated since you must revert the server to a previous state, increasing the risk of downtime.

Practical Advice

• Regularly audit your mutable infrastructure to ensure consistency and compliance.
• Consider using configuration management tools like Ansible or Chef to help manage and automate changes.

Step 2: Explore Immutable Infrastructure

Immutable infrastructure is a modern approach that promotes the idea of replacing servers rather than modifying them. Key aspects include:

• New Instances: Instead of updating servers, new instances are created from a pre-defined image, ensuring that all instances are identical.
• Consistency: Each deployment starts from the same image, eliminating configuration drift.
• Simplicity in Rollbacks: If an update fails, you can simply revert to the previous image by launching an earlier version.

Practical Advice

• Leverage version control for your images to maintain a history of changes and easily roll back to previous versions.
• Use Packer to automate the creation of these images, ensuring they are consistently built from the same source.

Step 3: Recognize the Benefits of Immutable Infrastructure

Understanding the benefits can help you appreciate why many organizations are shifting towards immutable infrastructure:

• Reliability: Reduces the chances of unexpected behaviors caused by server modifications.
• Speed: New instances can be launched quickly from pre-built images, enhancing deployment speed.
• Scalability: Scaling applications becomes easier as new instances can be spun up from the same image.

Common Pitfalls to Avoid

• Failing to test images before deploying them can lead to issues. Always validate your images in a staging environment.
• Overlooking the need for proper monitoring and logging can complicate troubleshooting.

Conclusion

In this tutorial, we explored the key differences between mutable and immutable infrastructure, focusing on how these concepts relate to Hashicorp Packer. Understanding these principles is essential as they lay the groundwork for effective automation and deployment strategies.

Next steps include diving deeper into Packer's functionalities and starting to create your own images using the tool. For additional resources, consider exploring the GitHub repository mentioned in the video.