Docker

Today I needed a postgres database for development that persisted its data when recreating the container. That’s not docker’s default behaviour, but docker volumes to the rescue!

This is the command to run a postgres container that persist it’s data in /var/yourpgdata:

docker run \
   --name pgresql \
   -d \
   -p 5432:5432 \
   -e POSTGRES_USER=yourpguser \
   -e POSTGRES_PASSWORD=yourpgpass \
   -e POSTGRES_DB=yourpgdb \
   -v /var/yourpgdata:/var/lib/postgresql/data

Fine… but what does this mean? Let me explain:

If you ever developed with Docker, you have to acknowledge that it is great!

Ok… you have to wrap your brain around an additional layer with all those caveats we know and love (volumes, path in- and outside of containers, …), but it lets you bundle all your dependencies at build time and then ship an image that will run in every docker-compatible runtime!

When you develop with Docker and do a lot of start/stop/build actions you will inevitably clutter your Docker Host with many unused containers.