Add Dockerfile and docker-compose to allow for multiple databases on …

…one postgres container

Dockerfile

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+FROM postgres:12.3
+
+COPY docker-entrypoint-initdb.d /docker-entrypoint-initdb.d

README.md

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 # yul-dc-postgres
-postgres image for yul-dc project
+Postgres image for yul-dc project
+
+Creates databases for Blacklight and Management projects in a single running container. 

docker-compose.yml

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+version: '3'
+
+services:
+  db:
+    build: .
+    image: 'curationexperts/dc-postgres:master'
+    ports:
+      - "5432:5432"
+    volumes:
+      - "db:/var/lib/postgresql/data"
+    environment:
+      POSTGRES_MULTIPLE_DATABASES: blacklight_yul_development,yul_dc_management_development
+      POSTGRES_USER: postgres
+      POSTGRES_PASSWORD: password
+
+volumes:
+  db:

docker-entrypoint-initdb.d/multiple-pg-databases.sh

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+#!/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