Filter by image registry

[feg545]

Is your feature request related to a problem? Please describe.

No

Describe the solution you'd like

Current Watchtower Capabilities

Watchtower currently supports the following container selection strategies:

• Monitoring all containers
• Monitoring containers by label
• Excluding containers using the disable-container label

Use Case

In a typical microservices project, I use Watchtower for continuous deployment. The project includes the following images or containers:

• mysql
• redis
• registry.mycompany.com/myproject/backend
• registry.mycompany.com/myproject/web

Problem

When deploying with docker stack, the container names are dynamically generated, making the disable-by-container-name method unusable.

Using labels to distinguish containers is feasible but requires modifying my docker-compose.yml, which is a bit cumbersome.

Suggestion

I would like Watchtower to support filtering based on image repository prefixes, such as filtering by registry.mycompany.com. These are our own custom images that should be auto-updated, while images like mysql and redis from the official Docker Hub don’t need to be updated frequently.

Proposed Design

I suggest that Watchtower introduces an environment variable to filter by image name before pulling. The filter should support:

• Comma-separated multiple filters
• Regular expression matching (preferred)

Example usage:

WATCHTOWER_IMAGE_FILTER=^registry.mycompany.com, /myproject/

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Describe alternatives you've considered

No

Additional context

No response

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