Docker Notes

Getting PostgreSQL Up & Running

So I don’t tear my hair out again figuring out how to make stuff work, here are the steps I’ve used to get a postgresql database up and running with Docker, initialised with a dump of our Trac database.

Getting our Trac database is fairly straight-forward with pg_dump.

We need to create a Dockerfile with the contents along the lines of:

FROM postgres:alpine

ADD . /docker-entrypoint-initdb.d

Copy our database here, call it something like trac.db.sql, and we’ll also add a user as well:

#!/bin/bash
set -e

psql -v ON_ERROR_STOP=1 --username "$POSTGRES_USER" <<-EOSQL
    CREATE USER trac;
    CREATE DATABASE trac;
    GRANT ALL PRIVILEGES ON DATABASE trac TO trac;
EOSQL

I’m not yet sure if adding the trac user is actually required or not, haven’t gotten that far.

Anyway, we can build with sudo docker build ..

Once we start it up, and init has finished, we can verify everything is running by connecting with psql, where $CONTAINER is the container we’ve started:

sudo docker run -it --rm --link $CONTAINER:postgres postgres:alpine psql -h postgres -U postgres

Can use commands like \list and \dt to confirm our database is configured correctly, and run some queries on the listed tables to ensure the data looks correct.

TODO: Use a separate data volume for the database files.

Additional information:

• https://hub.docker.com/_/postgres/
• https://github.com/docker-library/postgres/blob/master/9.6/alpine/docker-entrypoint.sh
• https://stackoverflow.com/questions/29946412/postgresql-and-docker
• https://dba.stackexchange.com/questions/1285/how-do-i-list-all-databases-and-tables-using-psql#1288
• https://ryaneschinger.com/blog/dockerized-postgresql-development-environment/

Next Steps

Next up is building a container for Trac, and getting it to communicate with our postgres container. We’ll probably want to have a separate container for the web server as well. Nginx or Apache2? I assume Trac can run under Nginx. It uses WSGI or whatever it is with Apache2…