Watchtower is a free, open source application that allows you to monitor the running Docker containers and updates them automatically if it finds any changes in their base images. When watchtower finds that a running container needs to be updated, it will gracefully stop the running container by sending it a SIGTERM signal. It will then download the new image, and finally restart the Container with the same options that were used when it was deployed initially. Everything will be done automatically on the background, so the user intervention is not required. In this guide, we will see how to automatically update running Docker containers using Watchtower in Unix-like operating systems.
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Reference:- This article was originally posted on BestDevOps.com