To install Docker on Alpine Linux, follow these steps:

apk add --update docker openrc
# Start the Docker daemon at boot
rc-update add docker boot
# Start the Docker daemon manually
service docker start
# Ensure the status is **running**
service docker status

If you encounter an unsatisfiable constraints error when trying to install Docker via the apk add command, it is likely because you do not have access to the Community repository. To rectify this issue, open your /etc/apk/repositories file and update accordingly.

# echo "http://dl-cdn.alpinelinux.org/alpine/latest-stable/community" >> /etc/apk/repositories

For more details about installing Docker on Alpine, refer to Alpine Linux documentation.