Docker and PostgreSQL for local development

What will be a software solution without a database system (or something similar)? It’s difficult to imagine.

Many times our software solutions requires a database system. However, I tend to avoid databases software installation, because these days we have docker 😀

This post is to document my way of Docker and PostgreSQL for local development. However this concept perfectly works for other databases systems.

Hooray, here is the goal:

• Use Docker and PostgreSQL for local development. Avoid installing a database system.
• Use Docker Volumes for data persistent (this helped in WSL2).
• Use Docker Networks to link our apps with our databases system.

Docker commands:

The following commands helped out when I was on in Windows 10 (Home :D) using WSL2. According to info I found, $PWD *should* work, but it did not. Creating a Docker volume was the way it worked.

create a volume in docker:

$ docker volume create --name volume_ttmo_demo_db

create a network for our application

$ docker network create network_ttmo_demo

Launch a Postgres container:

$ docker run --name container_ttmo_postgres -p 5432:5432 --network=network_ttmo_demo -v "volume_ttmo_demo_db:/var/lib/postgresql/data" -e POSTGRES_PASSWORD=super_secured_password -e POSTGRES_USER=user_ttmo_db -d postgres:13.2-alpine

Launch a psql console:

$ docker run -it --rm --network=network_ttmo_demo postgres:13.2-alpine psql -h localhost -U user_ttmo_db

the previous fails because localhost is not valid in docker network:

psql: error: could not connect to server: Connection refused
        Is the server running on host "localhost" (127.0.0.1) and accepting
        TCP/IP connections on port 5432?
could not connect to server: Address not available
        Is the server running on host "localhost" (::1) and accepting
        TCP/IP connections on port 5432?

it fails because locahost is not a valid name on the docker network, instead, as database server, we indicate the container name.

https://www.tutorialspoint.com/postgresql/postgresql_select_database.htm

Update parameters and re-execute psql console:

$ docker run -it --rm --network=network_ttmo_demo postgres:13.2-alpine psql -h container_ttmo_postgres -U user_ttmo_db
Password for user user_ttmo_db:
psql (13.2)
Type "help" for help.

user_ttmo_db=#

Now I can run psql commands:

\?: display help
\l: list all databases in server
\q: quit the psql shell
\c: connect to database
\dt: list tables in database

create database hello;  -> this creates a database

Cheers.