Checkpoint Support - A Journey Towards Predictable and Consistent Deployments
In the ever-evolving landscape of software development, ensuring predictability and consistency in deployments has always been a challenge. Our team faced similar hurdles, especially when managing historical versions of repositories. We needed a solution that could help us recreate environments from specific points in time, ensure reproducible deployments, and track changes in package behavior over time.
Inspired by the success stories of Ubuntu Snapshots on Azure and the increased security and resiliency of Canonical workloads on Azure, we embarked on a journey to develop a feature that could address these challenges.
The Problem
Imagine working on a project where you need to ensure that your deployment environment is consistent with a specific point in time. This is crucial for debugging, testing, and even for compliance purposes. However, without a robust system in place, managing and accessing historical versions of repositories can be a daunting task.
The Solution: Checkpoint
After weeks of brainstorming, development, and testing, we are thrilled to announce the release of the Checkpoint feature in Pulp! Think of it as similar to snapshot.debian.org or snapshot.ubuntu.com. This new addition allows you to manage and access historical versions of repositories, enhancing your content management capabilities. This feature is available as a tech-preview starting from Pulp version 3.74.0.
Key Benefits
- Historical Version Management: Easily recreate environments from specific points in time. This is particularly useful for debugging and compliance purposes.
- Reproducible Deployments: Ensure consistent replication of validated environments. This means that you can deploy the same environment multiple times with the same results.
- Structured Update Workflow: Track changes in package behavior over time. This helps in understanding how updates affect your environment and in planning future updates.
How It Works
The Checkpoint feature integrates seamlessly with Pulp, allowing you to create and manage checkpoints for your repositories. These checkpoints act as snapshots, capturing the state of your repository at a specific point in time. You can then use these checkpoints to recreate environments, ensuring that they are consistent with the state of the repository at the time the checkpoint was created.
For more details on how plugins can enable the checkpoint feature, check out this guide.
For repo admins looking to manage checkpoints for their repos, this guide provides all the necessary steps.
Example Usage with Pulp CLI
Here's a step-by-step example of how to use the checkpoint feature with the pulp CLI.
Setting Up the Repository, Remote, and Distributions
First, set up the repository, remote, and distributions:
pulp file remote create --url https://fixtures.pulpproject.org/file/PULP_MANIFEST --name myfile
pulp file repository create --name myfile --remote myfile
pulp file distribution create --name myfile --repository myfile --base-path myfile # regular distro
pulp file distribution create --checkpoint --name myfile-snapshot --repository myfile --base-path checkpoints/myfile # checkpoint distro
Creating an Empty Publication for Testing
Next, create an empty publication for testing purposes:
pulp file publication create --checkpoint --repository myfile # use "--checkpoint" to create the publication
http ${CONTENT_ADDR}/pulp/content/checkpoints/myfile/ # one checkpoint
HTTP/1.1 200 OK
Content-Length: 296
Content-Type: text/html
Date: Tue, 18 Mar 2025 14:04:11 GMT
Server: Python/3.10 aiohttp/3.8.1
X-PULP-CACHE: MISS
<html>
<head><title>Index of </title></head>
<body bgcolor="white">
<h1>Index of </h1>
<hr><pre><a href="../">../</a>
<a href="20250318T140338Z/">20250318T140338Z/</a> 18-Mar-2025 14:03
</pre><hr></body>
</html>
Syncing the Repository and Creating Another Checkpoint Publication
Sync the repository and create another checkpoint publication:
pulp file repository sync --name myfile
pulp file publication create --checkpoint --repository myfile
http ${CONTENT_ADDR}/pulp/content/checkpoints/myfile/
HTTP/1.1 200 OK
Content-Length: 448
Content-Type: text/html
Date: Tue, 18 Mar 2025 14:05:04 GMT
Server: Python/3.10 aiohttp/3.8.1
X-PULP-CACHE: MISS
<html>
<head><title>Index of </title></head>
<body bgcolor="white">
<h1>Index of </h1>
<hr><pre><a href="../">../</a>
<a href="20250318T140338Z/">20250318T140338Z/</a> 18-Mar-2025 14:03
<a href="20250318T140442Z/">20250318T140442Z/</a> 18-Mar-2025 14:04
</pre><hr></body>
</html>
http ${CONTENT_ADDR}/pulp/content/checkpoints/myfile/20250318T140442Z/
HTTP/1.1 200 OK
Content-Length: 835
Content-Type: text/html
Date: Tue, 18 Mar 2025 14:06:31 GMT
Server: Python/3.10 aiohttp/3.8.1
X-PULP-CACHE: MISS
<html>
<head><title>Index of /pulp/content/checkpoints/myfile/20250318T140442Z/</title></head>
<body bgcolor="white">
<h1>Index of /pulp/content/checkpoints/myfile/20250318T140442Z/</h1>
<hr><pre><a href="../">../</a>
<a href="1.iso">1.iso</a> 18-Mar-2025 14:04 1.0 kB
<a href="2.iso">2.iso</a> 18-Mar-2025 14:04 1.0 kB
<a href="3.iso">3.iso</a> 18-Mar-2025 14:04 1.0 kB
<a href="PULP_MANIFEST">PULP_MANIFEST</a> 18-Mar-2025 14:04 228 Bytes
</pre><hr></body>
</html>
Testing the Redirect
Finally, test the redirect by attempting to access a timestamp for which no checkpoint exists. The system will automatically redirect you to the nearest checkpoint created at or before the specified timestamp in the URL.
$ http ${CONTENT_ADDR}/pulp/content/checkpoints/myfile/20250318T140340Z/
HTTP/1.1 301 Moved Permanently
Content-Length: 22
Content-Type: text/plain; charset=utf-8
Date: Tue, 18 Mar 2025 14:09:19 GMT
Location: /pulp/content/checkpoints/myfile/20250318T140338Z/
Server: Python/3.10 aiohttp/3.8.1
301: Moved Permanently
Moving Towards SDP
The introduction of the Checkpoint feature is a significant step towards achieving Safe Deployment Practices (SDP). By ensuring that deployments are predictable and consistent, we can reduce the risk of errors and improve the overall quality of our software.
We are excited about the possibilities that the Checkpoint feature brings and look forward to seeing how it helps you in your projects.
Happy coding!