Docker-Compose freezing on database-creation - docker

Question

I wish to expand a web-application using docker (I'm beginner in Docker). My application demands PostgreSQL. Therefore I decided to use the docker-compose.
The docker-compose.yaml looks like:
version: '3.8'
services:
db:
image: postgres
command: "postgres -c listen_addresses='*'"
environment:
- POSTGRES_DB=CatsQMS
- POSTGRES_USER=postgres
- POSTGRES_PASSWORD=12345qwerty
application:
build: .
ports:
- "8080:8080"
depends_on:
- db
Also I have the file config.yaml which configures my web-application, it looks like this:
database_config:
host: db
user: postgres
password: 12345qwerty
port: 5432
database: CatsQMS
# Unimportant stuff
And when I lunch the docker-compose, using docker-compose up the build is freezing at this point:
Recreating cats_queue_management_system_db_1 ... done
Recreating cats_queue_management_system_application_1 ... done
Attaching to cats_queue_management_system_db_1, cats_queue_management_system_application_1
db_1 |
db_1 | PostgreSQL Database directory appears to contain a database; Skipping initialization
db_1 |
db_1 | 2020-05-20 13:42:51.628 UTC [1] LOG: starting PostgreSQL 12.3 (Debian 12.3-1.pgdg100+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 8.3.0-6) 8.3.0, 64-bit
db_1 | 2020-05-20 13:42:51.628 UTC [1] LOG: listening on IPv4 address "0.0.0.0", port 5432
db_1 | 2020-05-20 13:42:51.628 UTC [1] LOG: listening on IPv6 address "::", port 5432
db_1 | 2020-05-20 13:42:51.635 UTC [1] LOG: listening on Unix socket "/var/run/postgresql/.s.PGSQL.5432"
db_1 | 2020-05-20 13:42:51.660 UTC [24] LOG: database system was shut down at 2020-05-20 13:39:45 UTC
db_1 | 2020-05-20 13:42:51.673 UTC [1] LOG: database system is ready to accept connections
Perhaps it's an important thing, my Dockerfile:
FROM python:3.8
RUN mkdir /docker-entrypoint-initdb.d/
COPY ./application/sources/database/init.sql /docker-entrypoint-initdb.d/
RUN mkdir /app
WORKDIR /app
COPY . /app
RUN pip install -r requirements.txt
RUN python3 setup.py develop
ENTRYPOINT ["start_app", "-d"]
Where have I admitted a mistake?

Answer 1

Your application and PostgreSQL database are running and should work as expected. But Docker attached after running the containers to the db container.
You can avoid this by using the option -d or --detach on docker-compose up:
The docker-compose up command aggregates the output of each container (essentially running docker-compose logs -f). When the command exits, all containers are stopped. Running docker-compose up -d starts the containers in the background and leaves them running.
So your command looks like this:
docker-compose up -d

Answer 2

I don't think the issue is with the database container. It looks like it starts up normally and is listening for connections.
What is the ENTRYPOINT in your Dockerfile executing, "start_app"?
The -d argument looks like it may be starting the website as a daemon (background process) which doesn't give docker a process to hook into.
Maybe try
ENTRYPOINT ["start_app"]

Answer 3

Is the issue that your web app cant talk to the database? If so it might be that a) they don't share a network, and b) you're trying to connect on port 5432, but the postgres db container is not exposing or publishing this port.
I've added a few things to your docker-compose file that might make it work...
version: '3.8'
networks:
test:
services:
db:
image: postgres
command: "postgres -c listen_addresses='*'"
environment:
- POSTGRES_DB=CatsQMS
- POSTGRES_USER=postgres
- POSTGRES_PASSWORD=12345qwerty
ports:
- 5432:5432
networks:
- test
application:
build: .
ports:
- 8080:8080
networks:
- test
depends_on:
- db