Docker 101 Deck - Demo

step-by-step.md

Docker 101

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• Create a folder called demo

mkdir demo

• Create a Gemfile with the following contents

ruby '2.4.4'
source 'https://rubygems.org'

• Run:

touch Gemfile.lock

• Create a Dockerfile with the following contents

FROM ruby:2.4
RUN apt-get update -qq && apt-get install -y build-essential libpq-dev nodejs
RUN mkdir /demo
WORKDIR /demo
COPY Gemfile /demo/Gemfile
COPY Gemfile.lock /demo/Gemfile.lock
RUN bundle install
COPY . /demo

• Create a docker-compose.yml with the following contents

version: '3'
services:
  db:
    image: postgres
    volumes:
      - ./tmp/db:/var/lib/postgresql/data
  web:
    build: .
    command: bundle exec rails s -p 3000 -b '0.0.0.0'
    volumes:
      - .:/demo
    ports:
      - "3000:3000"
    depends_on:
      - db

• Run

docker-compose run web rails new . --force --database=postgresql

• Edit the config/database.yml file and replace the default section with:

default: &default
  adapter: postgresql
  encoding: unicode
  user: postgres
  password:
  host: db

• Run

docker-compose run web rake db:create
docker-compose up