Postgres docker: add additional database after initialization - postgresql

Question

I'm using Postgres within a docker-compose environment to host databases for multiple containers. I basically want to add a database per application directly from docker-compose without the need of manually creating the databases and users. For this, I'm using the init script feature of the Postgres docker image and copy the following bash script by mounting a volume:
db:
image: postgres:9.6
container_name: db
restart: always
volumes:
- postgres-data:/var/lib/postgresql/data
- /opt/docker/pgsql-entrypoint:/docker-entrypoint-initdb.d
environment:
- POSTGRES_PASSWORD={{ vault_pgsql_root_password }}
- POSTGRES_MULTIPLE_DATABASES=confluence-{{ confluence_pgsql_password }},keycloak-{{ keycloak_pgsql_password }},gitlab-{{ gitlab_pgsql_password }},jira-{{ jira_pgsql_password }}
Basically the POSTGRES_MULTIPLE_DATABASESenvironment variable contains all the databases and users that should be created. The password is as follows:
#!/bin/bash
set -e
set -u
function create_user_and_database() {
local database=$1
local password=$2
echo " Creating user and database '$database'"
psql -v ON_ERROR_STOP=1 --username "$POSTGRES_USER" <<-EOSQL
CREATE USER $database WITH PASSWORD '$password';
CREATE DATABASE $database;
GRANT ALL PRIVILEGES ON DATABASE $database TO $database;
EOSQL
}
if [ -n "$POSTGRES_MULTIPLE_DATABASES" ]; then
echo "Multiple database creation requested: $POSTGRES_MULTIPLE_DATABASES"
for entry in $(echo $POSTGRES_MULTIPLE_DATABASES | tr ',' ' '); do
db=$(echo $entry | cut -f1 -d-)
pw=$(echo $entry | cut -f2 -d-)
create_user_and_database $db $pw
done
echo "Multiple databases created"
fi
My problem is: at a certain point (now ;) ) I may want to add an additional service. Just adding an additional pair to the environment variable does not work, as the Postgres image is skipping the init step if data already exists. Is there a way to still achieve this behaviour?
Edit: I should have specified that i want to do it automatically from the compose file, by just changing the environment variable. It’s clear that it can be done manually of course.

Answer 1

You can always connect to the server with a database client and do it manually. If you don't want to expose the database port to the host then you can run the postgres client from the terminal in the postgres container. To open the terminal in the container:
> docker exec -it <container_name> /bin/sh
Then change users to postgres and start the client
# su postgres
postgres#1778e9755f65:/$ psql
Once inside just create a database:https://www.postgresql.org/docs/9.0/sql-createdatabase.html

Answer 2

I ended up not to use docker-compose but using sensible to deploy the database container directly and also make sure the appropriate users, databases and permissions are present. I could not find a meaningful way to do that during startup and environment variables.