Dockerizing a Rails application with docker-compose

Question

Hi I am trying to adapt my-app to docker.

My app stack is

Ruby 2.4.0
Rails 5.0.1
Postgres 9.5.8

I created a Dockerfile to create an image of my-app

FROM ruby:2.4

RUN apt-get update && apt-get install -y \
    software-properties-common \
    python-software-properties \
    build-essential \
    libpq-dev \
    libxml2-dev libxslt1-dev \
    libqt4-webkit libqt4-dev xvfb \
    nodejs \
    postgresql

RUN mkdir -p /usr/src/app
WORKDIR /usr/src/app

COPY Gemfile /usr/src/app
COPY Gemfile.lock /usr/src/app
RUN bundle install
ADD . /usr/src/app
COPY ./docker/docker-entrypoint.sh /usr/src/app/docker-entrypoint.sh
RUN chmod +x /usr/src/app/docker-entrypoint.sh
RUN bundle install

Then I created a docker-compose.yml

version: '3'
services:

  app:
    image: app_rails
    entrypoint: ['/usr/src/app/docker-entrypoint.sh']
    ports:
      - "3000:3000"
    depends_on:
      - postgres
    links:
      - postgres
    volumes:
      - .:/usr/src/app
    environment:
      DATABASE_URL: postgres://postgres@postgres@postgres:5432/postgres?pool=5&encoding=utf-8

  postgres:
    image: postgres:9.5.8
    ports:
     - "5432:5432"
    environment:
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: postgres
      POSTGRES_DB: postgres

And here is the script docker-entrypoint.sh

#!/bin/sh
set -e

host="$1"
echo "host: ${host}"

if [ "$#" -gt 0 ]; then shift; fi

until psql -h "$host" -U "postgres" -c '\q'; do
  >&2 echo "Postgres is unavailable - sleeping"
  sleep 1
done

rails db:create
rails db:migrate RAILS_ENV=development

bundle exec rails server -b 0.0.0.0

exec "$@"

and my database.yml

# SQLite version 3.x
#   gem install sqlite3
#
#   Ensure the SQLite 3 gem is defined in your Gemfile
#   gem 'sqlite3'
#
default: &default
  adapter: postgresql
  pool: 5
  timeout: 5000

development:
  adapter: postgresql
  database: app_development
  pool: 5
  timeout: 5000
  url: postgres://postgres@postgres/postgres:5432

test:
  adapter: postgresql
  database: app_test
  pool: 5
  timeout: 5000

production:
  adapter: postgresql
  database: app_production
  pool: 5
  timeout: 5000

I am having trouble running the script

web_1       |   connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?
web_1       | Postgres is unavailable - sleeping

Since I am new to docker an advise will be wellcome

Bret Fisher · Accepted Answer · 2017-11-23 05:06:14Z

2

You're DATABASE_URL can't be localhost, it needs to be the name of service. It also needs username and password in there:

postgres://postgres:postgres@postgres/postgres

It doesn't need post since it uses the default. Here's examples of URL's: https://stackoverflow.com/a/20722229/749924

edited Nov 23, 2017 at 5:06

answered Nov 22, 2017 at 20:33

Bret Fisher

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3 Comments

agusgambina Over a year ago

@Bret_Fisher thank you for your answer. It was very helpful to keep working. Sorry that I fully updated the question, but since your answer I was working in trying to make it work, but I am a little stuck. PS. I think your course in coursera is one of the best I took

Bret Fisher Over a year ago

I corrected my answer I had the : and @ backward :P

Bret Fisher Over a year ago

Tip: likely not related to your failure, but ideally you want your ENTRYPOINT to just do the wait and db migrate steps and then add a CMD to Dockerfile of bundle exec rails server -b 0.0.0.0 so it starts the server correctly.

Safi Nettah · Accepted Answer · 2017-11-22 14:14:36Z

1

Try

chmod +x /usr/src/my-app/docker-entrypoint.sh

to ensure your entry point is an executable

answered Nov 22, 2017 at 14:14

Safi Nettah

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4 Comments

agusgambina Over a year ago

thank you for your answer I already execute that in the Dockerfile

Safi Nettah Over a year ago

you run docker-compose as sudo ? and make chmod +x docker-entrypoint.sh before building the image

agusgambina Over a year ago

thank you, now it changed the output (I did not executed with sudo) I wrote it as an update of the question

agusgambina Over a year ago

sorry that I fully update the question, but I was working, and I stuck, but now is different. Your answer helped me to get to another point.

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