Rails by default comes with connection pooler on the application side but I always wonder what is the difference if we use another connection pooler such as PgBouncer. So, here is some notes on trying to understand some of it.

To try this out, I’m using docker so that I don’t have to install extra application:

$ mkdir conn-poc; cd conn-poc
$ rails new blog --api -T --database=postgresql

$ mkdir bouncer
$ mkdir db

# create docker network so that PgBouncer and PostgreSQL can communicate with eacher other
$ docker network create conn-poc-1-net

# start postgresql
$ cd db
$ docker run --rm \
  --net conn-poc-1-net \
  --name conn-poc-1-pg \
  -e POSTGRES_USER=postgres \
  -e POSTGRES_PASSWORD=postgres \
  -e POSTGRES_DB=blog_development \
  -v $(pwd):/var/lib/postgresql/data  \
  -p 6432:5432 \
  -it postgres:13.8-alpine

# start pgbouncer
$ cd bouncer
$ docker run --rm \
  --net conn-poc-1-net \
  --name conn-poc-1-bouncer \
  -e DATABASE_URL="postgres://postgres:postgres@conn-poc-1-pg/blog_development" \
  -v $(pwd):/etc/pgbouncer \
  -p 7432:5432 \
  edoburu/pgbouncer

PgBouncer config:

In the previous post, we managed to figure out a way to make our Docker setup work for Development. It’s time to figure out how we can run our tests with it. In the end, we should be able to run single and multiple tests. This also includes Capybara tests using headless Chrome.

We will also look into how to use multiple docker-compose files to override what we have based on the environment. But we’ll start with something simple first.

Check out my previous post if you want to start learning from just a Dockerfile. As you may have realized, it’s not scalable if we keep on using the long command to manage our containers. We haven’t even started talking about different services such as PostgreSQL and Redis, yet.

In this post, we are aiming to use docker-compose to make our development experience easier.

Prepare our application

I’m assuming we are starting from fresh where we don’t have any Ruby on Rails application ready, yet. I’ll put a note later if you are starting with an existing application.

I think everyone knows by now how good Docker is in making sure we have almost the same setup everywhere. However, I think it is not easy as everyone thought for people new to it. There are just so many questions that I have to the point they discouraged me from using it as my daily driver.

I decided to spend some time to look into this and document this journey through this blog post. I hope this will help me and you in learning this awesome service. There will be more after this, but we will start with this one first.