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@@ -1,14 +1,20 @@
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----
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-layout: default
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-title: Getting started with Compose and Rails
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----
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+page_title: Quickstart Guide: Compose and Rails
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+page_description: Getting started with Docker Compose and Rails
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+page_keywords: documentation, docs, docker, compose, orchestration, containers,
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+rails
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-Getting started with Compose and Rails
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-==================================
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-We're going to use Compose to set up and run a Rails/PostgreSQL app. Before starting, you'll need to have [Compose installed](install.md).
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+## Getting started with Compose and Rails
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-Let's set up the three files that'll get us started. First, our app is going to be running inside a Docker container which contains all of its dependencies. We can define what goes inside that Docker container using a file called `Dockerfile`. It'll contain this to start with:
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+This Quickstart guide will show you how to use Compose to set up and run a Rails/PostgreSQL app. Before starting, you'll need to have [Compose installed](install.md).
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+
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+### Define the project
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+
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+Start by setting up the three files you'll need to build the app. First, since
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+your app is going to run inside a Docker container containing all of its
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+dependencies, you'll need to define exactly what needs to be included in the
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+container. This is done using a file called `Dockerfile`. To begin with, the
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+Dockerfile consists of:
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FROM ruby:2.2.0
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RUN apt-get update -qq && apt-get install -y build-essential libpq-dev
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@@ -18,14 +24,14 @@ Let's set up the three files that'll get us started. First, our app is going to
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RUN bundle install
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ADD . /myapp
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-That'll put our application code inside an image with Ruby, Bundler and all our dependencies. For more information on how to write Dockerfiles, see the [Docker user guide](https://docs.docker.com/userguide/dockerimages/#building-an-image-from-a-dockerfile) and the [Dockerfile reference](http://docs.docker.com/reference/builder/).
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+That'll put your application code inside an image that will build a container with Ruby, Bundler and all your dependencies inside it. For more information on how to write Dockerfiles, see the [Docker user guide](https://docs.docker.com/userguide/dockerimages/#building-an-image-from-a-dockerfile) and the [Dockerfile reference](http://docs.docker.com/reference/builder/).
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-Next, we have a bootstrap `Gemfile` which just loads Rails. It'll be overwritten in a moment by `rails new`.
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+Next, create a bootstrap `Gemfile` which just loads Rails. It'll be overwritten in a moment by `rails new`.
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source 'https://rubygems.org'
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gem 'rails', '4.2.0'
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-Finally, `docker-compose.yml` is where the magic happens. It describes what services our app comprises (a database and a web app), how to get each one's Docker image (the database just runs on a pre-made PostgreSQL image, and the web app is built from the current directory), and the configuration we need to link them together and expose the web app's port.
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+Finally, `docker-compose.yml` is where the magic happens. This file describes the services that comprise your app (a database and a web app), how to get each one's Docker image (the database just runs on a pre-made PostgreSQL image, and the web app is built from the current directory), and the configuration needed to link them together and expose the web app's port.
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db:
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image: postgres
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@@ -41,11 +47,16 @@ Finally, `docker-compose.yml` is where the magic happens. It describes what serv
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links:
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- db
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-With those files in place, we can now generate the Rails skeleton app using `docker-compose run`:
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+### Build the project
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+
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+With those three files in place, you can now generate the Rails skeleton app
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+using `docker-compose run`:
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$ docker-compose run web rails new . --force --database=postgresql --skip-bundle
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-First, Compose will build the image for the `web` service using the `Dockerfile`. Then it'll run `rails new` inside a new container, using that image. Once it's done, you should have a fresh app generated:
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+First, Compose will build the image for the `web` service using the
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+`Dockerfile`. Then it'll run `rails new` inside a new container, using that
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+image. Once it's done, you should have generated a fresh app:
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$ ls
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Dockerfile app docker-compose.yml tmp
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@@ -54,17 +65,26 @@ First, Compose will build the image for the `web` service using the `Dockerfile`
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README.rdoc config.ru public
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Rakefile db test
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-Uncomment the line in your new `Gemfile` which loads `therubyracer`, so we've got a Javascript runtime:
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+Uncomment the line in your new `Gemfile` which loads `therubyracer`, so you've
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+got a Javascript runtime:
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gem 'therubyracer', platforms: :ruby
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-Now that we've got a new `Gemfile`, we need to build the image again. (This, and changes to the Dockerfile itself, should be the only times you'll need to rebuild).
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+Now that you've got a new `Gemfile`, you need to build the image again. (This,
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+and changes to the Dockerfile itself, should be the only times you'll need to
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+rebuild.)
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$ docker-compose build
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-The app is now bootable, but we're not quite there yet. By default, Rails expects a database to be running on `localhost` - we need to point it at the `db` container instead. We also need to change the database and username to align with the defaults set by the `postgres` image.
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+### Connect the database
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+
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+The app is now bootable, but you're not quite there yet. By default, Rails
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+expects a database to be running on `localhost` - so you need to point it at the
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+`db` container instead. You also need to change the database and username to
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+align with the defaults set by the `postgres` image.
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-Open up your newly-generated `database.yml`. Replace its contents with the following:
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+Open up your newly-generated `database.yml`file. Replace its contents with the
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+following:
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development: &default
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adapter: postgresql
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@@ -79,23 +99,25 @@ Open up your newly-generated `database.yml`. Replace its contents with the follo
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<<: *default
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database: myapp_test
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-We can now boot the app.
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+You can now boot the app with:
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$ docker-compose up
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-If all's well, you should see some PostgreSQL output, and then—after a few seconds—the familiar refrain:
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+If all's well, you should see some PostgreSQL output, and then—after a few
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+seconds—the familiar refrain:
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myapp_web_1 | [2014-01-17 17:16:29] INFO WEBrick 1.3.1
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myapp_web_1 | [2014-01-17 17:16:29] INFO ruby 2.2.0 (2014-12-25) [x86_64-linux-gnu]
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myapp_web_1 | [2014-01-17 17:16:29] INFO WEBrick::HTTPServer#start: pid=1 port=3000
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-Finally, we just need to create the database. In another terminal, run:
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+Finally, you need to create the database. In another terminal, run:
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$ docker-compose run web rake db:create
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-And we're rolling—your app should now be running on port 3000 on your docker daemon (if you're using boot2docker, `boot2docker ip` will tell you its address).
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+That's it. Your app should now be running on port 3000 on your Docker daemon (if
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+you're using Boot2docker, `boot2docker ip` will tell you its address).
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-## Compose documentation
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+## More Compose documentation
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- [Installing Compose](install.md)
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- [User guide](index.md)
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