localhost doesn't work when I dockerize postgres with Django - django

Question

My system is Ubuntu 22.04.1 LTS.
I was going through the Django for professionals book and follow all line by line but somehow when i dockerize my django project with postgres it just doesn't run localhost properly, with sqlite all works fine.
Dockerfile
# Pull base image
FROM python:3.10.6-slim-bullseye
# Set environment variables
ENV PIP_DISABLE_PIP_VERSION_CHECK 1
ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1
# Set work directory
WORKDIR /code
# Install dependencies
COPY ./requirements.txt .
RUN pip install -r requirements.txt
# Copy project
COPY . .
docker-compose.yml
version: "3.9"
services:
web:
build: .
command: python /code/manage.py runserver 0.0.0.0:8000
volumes:
- .:/code
ports:
- 8000:8000
depends_on:
- db
db:
image: postgres:13
volumes:
- postgres_data:/var/lib/postgresql/data/
environment:
- "POSTGRES_HOST_AUTH_METHOD=trust"
volumes:
postgres_data:
django.settings.py
DATABASES = {
"default": {
"ENGINE": "django.db.backends.postgresql",
"NAME": "postgres",
"USER": "postgres",
"PASSWORD": "postgres",
"HOST": "db", # set in docker-compose.yml
"PORT": 5432, # default postgres port
}
}
When I run docker-compose up that shows and seems like all must be fine, but somehow it just doesn't work:
Attaching to ch3-postgresql_web_1, ch3-postgresql_db_1
web_1 | Watching for file changes with StatReloader
web_1 | Performing system checks...
web_1 |
web_1 | System check identified no issues (0 silenced).
db_1 |
db_1 | PostgreSQL Database directory appears to contain a database; Skipping initialization
db_1 |
db_1 | 2022-12-05 11:58:21.572 UTC [1] LOG: starting PostgreSQL 13.9 (Debian 13.9-1.pgdg110+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 10.2.1-6) 10.2.1 20210110, 64-bit
db_1 | 2022-12-05 11:58:21.574 UTC [1] LOG: listening on IPv4 address "0.0.0.0", port 5432
db_1 | 2022-12-05 11:58:21.575 UTC [1] LOG: listening on IPv6 address "::", port 5432
db_1 | 2022-12-05 11:58:21.577 UTC [1] LOG: listening on Unix socket "/var/run/postgresql/.s.PGSQL.5432"
db_1 | 2022-12-05 11:58:21.580 UTC [26] LOG: database system was shut down at 2022-12-05 11:58:17 UTC
db_1 | 2022-12-05 11:58:21.584 UTC [1] LOG: database system is ready to accept connections
And when I go to the url 127.0.0.1:8000:
This site can’t be reached
The webpage at http://127.0.0.1:8000/ might be temporarily down or it may have moved permanently to a new web address.
ERR_SOCKET_NOT_CONNECTED
If i wait some time and then check docker-compose logs, this messages appears
psycopg2.OperationalError: connection to server at "db" (172.21.0.2), port 5432 failed: Connection timed out
web_1 | Is the server running on that host and accepting TCP/IP connections?
I spend a lot of hours of searching for info about this problem but nothing did help. I try even to reinstall different versions of Postgres and docker.

Answer 1

Simply try this:
change this:
volumes:
- postgres_data:/var/lib/postgresql/data/
To this:
volumes:
- postgres_data:/var/lib/postgresql/data #removed forward slash from here.
Try above thing and see if it solves that problem.
Note: after making above changes don't forget to re-build docker-compsoe

Answer 2

You will need to add more environment variables to make the PostgreSQL work.
Please refer to https://hub.docker.com/_/postgres "Environment Variables"
The only variable required is POSTGRES_PASSWORD, the rest are optional.
db:
image: postgres:13
volumes:
- postgres_data:/var/lib/postgresql/data/
environment:
- POSTGRES_USER=postgres
- POSTGRES_PASSWORD=postgres
- POSTGRES_DB=postgres
- POSTGRES_HOST_AUTH_METHOD=trust
And, you are encouraged to make your docker compose file more secure:
db:
image: postgres:13
volumes:
- postgres_data:/var/lib/postgresql/data/
env_file:
- .env.dev
.env.dev
POSTGRES_USER=postgres
POSTGRES_PASSWORD=postgres
POSTGRES_DB=postgres
POSTGRES_HOST_AUTH_METHOD=trust