I run postgres inside the docker container to limit the amount of system resources available to it. I'm having trouble understanding how to make data persistent. I read the following articles:
https://www.andreagrandi.it/2015/02/21/how-to-create-a-docker-image-for-postgresql-and-persist-data/
http://container42.com/2013/12/16/persistent-volumes-with-docker-container-as-volume-pattern/
We suggest using a container with data, and then associate a postgres container with it. What I do not understand, what is the advantage for this? As far as I can tell, if for some reason the docker machine shuts down (for example, moving it to another physical machine), the data-only container will stop working and all content will be lost? I tried to create the volume in the postgres container, but in fact it does not save anything to disk.
Here is my docker file. What am I doing wrong?
FROM ubuntu MAINTAINER Andrew Broadbent < andrew.broadbent@manchester.ac.uk > # Add the PostgreSQL PGP key to verify their Debian packages. # It should be the same key as https://www.postgresql.org/media/keys/ACCC4CF8.asc RUN apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys B97B0AFCAA1A47F044F244A07FCC7D46ACCC4CF8 # Add PostgreSQL repository. It contains the most recent stable release # of PostgreSQL, ``9.3``. RUN echo "deb http://apt.postgresql.org/pub/repos/apt/ precise-pgdg main" > /etc/apt/sources.list.d/pgdg.list # Install ``python-software-properties``, ``software-properties-common`` and PostgreSQL 9.3 # There are some warnings (in red) that show up during the build. You can hide # them by prefixing each apt-get statement with DEBIAN_FRONTEND=noninteractive RUN apt-get update && apt-get install -y python-software-properties software-properties-common postgresql-9.3 postgresql-client-9.3 postgresql-contrib-9.3 # Note: The official Debian and Ubuntu images automatically ``apt-get clean`` # after each ``apt-get`` # Run the rest of the commands as the ``postgres`` user created by the ``postgres-9.3`` package when it was ``apt-get installed`` USER postgres # Create a PostgreSQL role named ``docker`` with ``docker`` as the password and # then create a database `docker` owned by the ``docker`` role. # Note: here we use ``&&\`` to run commands one after the other - the ``\`` # allows the RUN command to span multiple lines. RUN /etc/init.d/postgresql start &&\ psql --command "CREATE USER docker WITH SUPERUSER PASSWORD 'docker';" &&\ createdb -O docker docker # Complete configuration USER root RUN echo "host all all 0.0.0.0/0 md5" >> /etc/postgresql/9.3/main/pg_hba.conf RUN echo "listen_addresses='*'" >> /etc/postgresql/9.3/main/postgresql.conf # Expose the PostgreSQL port EXPOSE 5432 # Add VOLUMEs to allow backup of config, logs and databases RUN mkdir -p /var/run/postgresql && chown -R postgres /var/run/postgresql VOLUME ["/etc/postgresql", "/var/log/postgresql", "/var/lib/postgresql"] # Set the default command to run when starting the container USER postgres CMD ["/usr/lib/postgresql/9.3/bin/postgres", "-D", "/var/lib/postgresql/9.3/main", "-c", "config_file=/etc/postgresql/9.3/main/postgresql.conf"]
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