How to automatically update your docker containers, if base-images are updated

Question

Say I have a trivial container based on the ubuntu:latest. Now there is a security update and ubuntu:latest is updated in the docker repo .

Answer 1

Here is a simplest way to update docker container automatically

Put the job via $ crontab -e:

0 * * * * sh ~/.docker/cron.sh

Create dir ~/.docker with file cron.sh:

#!/bin/sh
if grep -Fqe "Image is up to date" << EOF
`docker pull ubuntu:latest`
EOF
then
    echo "no update, just do cleaning"
    docker system prune --force
else
    echo "newest exist, recompose!"
    cd /path/to/your/compose/file
    docker-compose down --volumes
    docker-compose up -d
fi