jsugarman / test-alpine

How to dockerize rails 5 with postgres on Alpine (linux)

Dockerized Rails on alpine

Example rails 5 app using docker compose to run the app in an Alpine (linux) container

Prerequisites

• clone repo
• install docker v3+ (for mac or otherwise)

Building using docker-compose

For docker-compose certain options should ideally be set in the docker-compose.yml file. Environment variables, in particular, are better specified in there using the environment: key.

Build containers:

docker-compose build

Run containers:

docker-compose up

Build and run:

docker-compose up --build

Create/migrate DB: with the docker containers running (docker-compose up) in another terminal

# In another terminal while containers running
docker-compose run --rm web bundle exec rails db:setup
docker-compose run --rm web bundle exec rails db:migrate

Interactive shell in web (app) container:

$ docker-compose exec web sh
/app # rails console
irb(main):001:0> Employee.first

Interactive shell in db container, login to postgres, connect to apps db, query first employee

$ docker-compose exec db sh
/# psql -U postgres
postgres=# \c db
db=# select * from employees limit(1);

Test: localhost

Building Using plain docker

WARNING: For this to work you will need to uncomment/create an ENTRYPOINT/CMD in the dockerfile add ENV DATABASE_URL=postgres://postgres@db to the Dockerfile. I have not test this since moving to docker-compose though.

Build:

docker build -f Dockerfile -t rails-alpine-test:latest .

Run:

docker run -it -p 80:5000 rails-alpine-test:latest

Docker cleanup cheatsheet

see linuxize

• cleanup containers

# list all containers
docker container ls -a

# remove all stopped containers, dangling images
# and unused networks (and volumes with option)
docker system prune
docker system prune --volumes

# list all stopped containers
docker container ls -a --filter status=exited --filter status=created

# remove all stopped containers
docker container prune

• cleanup images

# list all images
docker image ls -a

# remove all images not referenced by an existing container
docker image prune -a

# remove all images not referenced by an existing container created more than 12hours ago
docker image prune -a --filter "until=12h"

# Hard ball it
# Stop all containers, remove all containers, remove all unreferenced images
docker container stop $(docker container ls -aq)
docker container prune
docker image prune -a

Useful links

dockerize-a-rails-5-postgres-redis-sidekiq-action-cable-app-with-docker-compose

linuxize