Restore SQL dump in PostgreSQL 11 Docker at image build time - postgresql

Question

I want to build a custom Postgres11 image in which some users are created and some extensions are installed. As I want these to be created at build time, so I don't want to use docker-entrypoint-initdb.d. A next step would be to restore a sql dump as well.
FROM postgres:11
ENV PG_MAJOR 11
ENV POSTGISV 2.5
ENV TZ Europe/Brussels
RUN apt-get update \
&& apt-get install -y --no-install-recommends \
postgresql-$PG_MAJOR-postgis-$POSTGISV \
postgresql-$PG_MAJOR-postgis-$POSTGISV-scripts
USER postgres
RUN initdb && pg_ctl -o "-c listen_addresses='*'" start &&\
psql -h 0.0.0.0 --command "CREATE USER docker WITH SUPERUSER PASSWORD 'docker';" &&\
psql -h 0.0.0.0 --command "CREATE USER akela_test WITH PASSWORD 'akela';" &&\
createdb -E UTF8 -U postgres -h 0.0.0.0 -O akela_test akela_test --template template0 &&\
psql -U postgres -d akela_test -h 0.0.0.0 -c 'CREATE EXTENSION IF NOT EXISTS "hstore";' &&\
psql -U postgres -d akela_test -h 0.0.0.0 -c 'CREATE EXTENSION IF NOT EXISTS "postgis";' &&\
psql -U postgres -d akela_test -h 0.0.0.0 -c 'CREATE EXTENSION IF NOT EXISTS "uuid-ossp";' &&\
psql -U postgres -d akela_test -h 0.0.0.0 -c "CREATE ROLE akela_db WITH LOGIN PASSWORD 'akela'" &&\
psql -U postgres -d akela_test -h 0.0.0.0 -c "GRANT ALL PRIVILEGES ON DATABASE akela_test to akela_db" &&\
psql -U postgres -d akela_test -h 0.0.0.0 -c "CREATE schema db" &&\
pg_ctl stop
# gunzip -c /tmp/dump.sql.gz | psql -U akela -h 0.0.0.0 akela
USER root
seems to work:
...
CREATE SCHEMA
ALTER SCHEMA
CREATE ROLE
GRANT
CREATE SCHEMA
ALTER SCHEMA
waiting for server to shut down....2019-07-08 12:58:06.962 CEST [22] LOG: received fast shutdown request
2019-07-08 12:58:06.964 CEST [22] LOG: aborting any active transactions
2019-07-08 12:58:06.965 CEST [22] LOG: background worker "logical replication launcher" (PID 29) exited with exit code 1
2019-07-08 12:58:06.965 CEST [24] LOG: shutting down
2019-07-08 12:58:07.006 CEST [22] LOG: database system is shut down
done
server stopped
...
running the image however shows no users nor db:
postgres=# \l
List of databases
Name | Owner | Encoding | Collate | Ctype | Access privileges
-----------+----------+----------+------------+------------+-----------------------
postgres | postgres | UTF8 | en_US.utf8 | en_US.utf8 |
template0 | postgres | UTF8 | en_US.utf8 | en_US.utf8 | =c/postgres +
| | | | | postgres=CTc/postgres
template1 | postgres | UTF8 | en_US.utf8 | en_US.utf8 | =c/postgres +
| | | | | postgres=CTc/postgres
(3 rows)
postgres=# \du
List of roles
Role name | Attributes | Member of
-----------+------------------------------------------------------------+-----------
postgres | Superuser, Create role, Create DB, Replication, Bypass RLS | {}
What could be the issue?

Answer 1

The Dockerfile for postgres defines a volume which means any changes to this directory by a RUN step will be discarded. To make changes to this directory you need to do one of the following options:
Make the changes at run time rather than doing the build, and save the resulting volume.
Make changes during the build, but in a different directory. This would require changing the postgres configuration to use the different directory.
Save your changes to a different directory and then restore those changes when you start the container (see the save and load volume scripts for an example of this).
Build your own postgres image without the volume definition.