Sometimes, we need to have multiple database instances to test our projects. Until now, Docker and Docker Compose don't have an easy alternative to resolve this.
Some people (and I) have gotten around this by creating services for each database they need:
### docker-compose.yaml
services:
postgres_1:
image: postgres:latest
postgres_2:
image: postgres:latest
I resolved this by adding a new entrypoint and setting a environment var in the Docker Compose Service for Postgres:
The container entrypoint:
### entrypoint.sh
#!/bin/bash
set -e
set -u
function create_user_and_database() {
local database=$1
echo " Creating user and database '$database'"
psql -v ON_ERROR_STOP=1 --username "$POSTGRES_USER" <<-EOSQL
CREATE USER $database;
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 db in $(echo $POSTGRES_MULTIPLE_DATABASES | tr ',' ' '); do
create_user_and_database $db
done
echo "Multiple databases created"
fi
And the docker-compose service:
### docker-compose.yaml
postgres:
image: postgres:alpine
container_name: postgres
restart: unless-stopped
ports:
- 5432:5432
environment:
POSTGRES_PASSWORD: "postgres"
POSTGRES_MULTIPLE_DATABASES: users, products, orders
healthcheck:
test: ["CMD-SHELL", "pg_isready -U postgres"]
interval: 5s
timeout: 5s
retries: 5
volumes:
- ./<path-of-the-entrypoint>/multiple-databases.sh:/docker-entrypoint-initdb.d/multiple-databases.sh
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