Docker Postgres running multiple dockers with segregated instances - postgresql

Question

I have a requirement with docker/docker-compose to run 2 different instances of postgres but i need their data to be completely separate as both applications control the database server completely, not just a single database
Here is the docker file there is one in each project directory
FROM postgres:10-alpine
COPY data/resources.sql.gz /docker-entrypoint-initdb.d/resources.sql.gz
ENV POSTGRES_USER=postgres
ENV POSTGRES_PASSWORD=123456
Here is the section from each docker compose, there is one in each project directory
Project 1
db_test:
image: postgres:10-alpine
container_name: postgres_test
restart: always
expose:
- '5432'
environment:
- POSTGRES_USER=postgres
- POSTGRES_PASSWORD=123456
- PGDATA=/db
volumes:
- ./db:/db
networks:
backend:
ipv4_address: 172.16.1.6
Project 2
db:
image: postgres:10-alpine
container_name: postgres
restart: always
expose:
- '5432'
environment:
- POSTGRES_USER=postgres
- POSTGRES_PASSWORD=123456
- PGDATA=/db
volumes:
- ./db:/db
networks:
backend:
ipv4_address: 172.16.0.6
I should also note that the resources.sql.gz is unique to each project
The problem i am having is that i build project 1, then stop the docker
then i build project 2 and for some reason its inheriting the databases from project 1
what i need is to completely seperate both so that i could run them side by side with different ports (if required)

Answer 1

One option is to create two distinct docker volumes:
docker-compose.yml
version: "3.7"
volumes:
db1-pgdata-volume:
name: db1-postgres-data
db2-pgdata-volume:
name: db2-postgres-data
services:
db_test:
image: postgres:10-alpine
container_name: postgres_test
restart: always
expose:
- '5432'
environment:
- POSTGRES_USER=postgres
- POSTGRES_PASSWORD=123456
- PGDATA=/db
volumes:
- db1-pgdata-volume:/var/lib/postgresql/data
networks:
backend:
ipv4_address: 172.16.1.6
db:
image: postgres:10-alpine
container_name: postgres
restart: always
expose:
- '5432'
environment:
- POSTGRES_USER=postgres
- POSTGRES_PASSWORD=123456
- PGDATA=/db
volumes:
- db2-pgdata-volume:/var/lib/postgresql/data
networks:
backend:
ipv4_address: 172.16.0.6

Answer 2

You are using the same database storage for both services. It's like you're using a single database with two access points.
Change the volumes section to this :
in db service :
volumes:
- ./db:/var/lib/postgresql/data
in db_test service:
volumes:
- ./db_test:/var/lib/postgresql/data
Remove the following from the environment section :
- PGDATA=/db