Watchtower

Since it enables you to package your apps with a dockerfile, build, push to a registry and deliver it to the cloud provider, it is no wonder that dockers are the buzz nowadays. Then again, things can become even simpler with applications such as Watchtower that enable the automation of the Docker container and ensure base image updates.

The idea behind the tool is to keep a close eye on the running docker container and identify changes to the images. Once a change is detected, the app automatically restarts the container using the new image.

The obvious advantage here is that you can easily update the apps in the container by simply pushing a new image to the docker hub or the image registry. Simply put, the app takes the new image, closes the container and restarts it with a new version without messing with your configured settings.

As previously mentioned, the program can monitor all running containers by default. However, if you prefer it to keep a close eye solely on certain subsets, then you can do so via arguments. You can configure the tool to monitor specific containers by specifying their names when launching the app. And yes, this means that the rest of the containers are going to be ignored.

The other arguments that you may use to simplify the maintenance of the containers include setting a time zone, removing the old images or attached volumes following the update, scheduling, setting a timeout or verifying the server's TLS certificate, just to name a few.

Another neat feature of the tool is that it is able to interpret the links between different containers you are running together or that are co-dependent. If Watchtower detects an update for one of the containers in a group linked together, it stops and restarts all of them in the correct order so that the app is restarted correctly.