Expose OCI image labels in notification templates

Feature Request Checklist

• I checked existing issues and discussions for duplicates.
• This is a feature request, not a support question.

Problem Description

Currently there is no way to include the actual image version in notification templates (for example 1.14.3).

The report templates only expose limited information from ContainerReport, such as:

• Name
• ImageName
• CurrentImageID
• LatestImageID

This means notifications can only show image IDs or tags, but not the real version metadata of the image.

Many container images provide version metadata via OCI labels, for example:

org.opencontainers.image.version

However, these labels are not currently exposed in the notification template data model.

As a result, even if an image includes a proper OCI version label, Watchtower notifications cannot show version changes like:

jellyfin updated: 10.11.5 → 10.11.6

Desired Solution

Expose OCI image labels (or at least org.opencontainers.image.version) in the notification template context.

One possible approach would be expanding ContainerReport to include metadata from the inspected images, for example:

CurrentImageLabels map[string]string
LatestImageLabels  map[string]string

This would allow templates such as:

{{ index .CurrentImageLabels "org.opencontainers.image.version" }}
→
{{ index .LatestImageLabels "org.opencontainers.image.version" }}

Alternatively, exposing the full Docker image inspect metadata (similar to .Config.Labels) would also solve this.

This would make it possible to generate much more useful notifications like:

jellyfin updated: 10.11.5 → 10.11.6

instead of only:

jellyfin updated: d8fd457232c0 → 28e5341a13af

Current Alternatives or Workarounds

Currently there does not seem to be a clean workaround.

The only possible approaches appear to be:

• parsing versions from image tags (which does not work when using latest)
• running external scripts that call docker inspect after updates
• building a custom notification system outside of Watchtower

None of these approaches integrate cleanly with Watchtower's notification templates.

Additional Context

Many users rely on the latest tag together with Watchtower auto-updates. OCI labels are often the only reliable way to determine the actual image version. Including this metadata in notifications would allow meaningful update messages without changing existing workflows.