I've been running Watchtower in monitor-only mode for about three days. It keeps notifying me that certain containers have updates available, including the same containers every day. However, when I run docker pull manually, Docker reports that the images are already up to date. What explains the mismatch, and what is the correct way to apply the updates?
2 Answers
Also check which Watchtower build you’re using. The original project has been inactive for a long time, while a maintained continuation exists. An old build may have compatibility problems with newer Docker API versions and could produce unreliable update checks. Updating Watchtower or switching to a maintained version is worth considering if the behavior continues.
In monitor-only mode, Watchtower can detect and pull a newer image, but it won’t recreate or replace the running container. After the image has been pulled, running docker pull yourself will naturally say it’s current, while the existing container is still using the old image. Recreate the affected services with `docker compose up -d` so they start from the newly pulled images. `--force-recreate` usually isn’t necessary unless Compose doesn’t detect a change or you specifically want to force it.
Exactly—the important distinction is between the image in the local cache and the container that was created from an older image. Pulling alone doesn’t update an already-running container.