Demo Image promotion and Garbage Collection

Optimize your Docker image workflow by configuring automatic image promotions from development to production repositories and managing storage with garbage collection in Docker Trusted Registry (DTR).

Table of Contents

1. Configure Image Promotion Policy
2. Push and Promote an Image
3. Configure Garbage Collection
4. Links and References

Configure Image Promotion Policy

First, set up an automated policy to move images tagged as stable from your development repository (devimages) to production (prodimages).

1. In the DTR UI, go to Repositories and select devimages.
2. Click Promotions and choose Tag Name as the criterion.
3. Define the rule:
   • tagName == "stable"
4. Click Add.
5. Under Target Repository, pick prodimages.
6. For Target Tag Name, enter %n to preserve the original tag.
7. Save by clicking Save and Apply.

After saving, you’ll see the new policy listed with Last Promoted set to never until it runs for the first time.

Push and Promote an Image

Tag and push an image with stable on your local machine to trigger the promotion:

# Tag alpine:latest for devimages
docker tag alpine:latest 54.145.234.153/yogeshraheja/devimages:stable

# Push to the devimages repository
docker push 54.145.234.153/yogeshraheja/devimages:stable

Return to the DTR console:

1. Refresh devimages.
2. Under Promotions, Last Promoted will update to the current timestamp.
3. Click Activity to view the detailed promotion log.

To confirm, inspect prodimages:

The stable (Promoted) tag indicates that the image has been moved successfully.

Configure Garbage Collection

Over time, untagged images accumulate and consume disk space. DTR’s Garbage Collection removes these images based on your schedule.

1. Navigate to System > Garbage Collection in the DTR UI.
2. Choose a collection mode:

3. (Optional) Schedule it using a cron expression for regular cleanups.
4. Click Save to apply.

Links and References

• Docker Trusted Registry Overview
• Manage Images with DTR
• Docker Docs: Garbage Collection