Deploying Ruby applications in tsuru¶

Overview¶

This document is a hands-on guide to deploying a simple Ruby application in Tsuru. The example application will be a very simple Rails project associated to a MySQL service.

Creating the app within tsuru¶

To create an app, you use app-create command:

$ tsuru app-create <app-name> <app-platform>

For Ruby, the app platform is, guess what, ruby! Let’s be over creative and develop a never-developed tutorial-app: a blog, and its name will also be very creative, let’s call it “blog”:

$ tsuru app-create blog ruby

To list all available platforms, use platform-list command.

You can see all your applications using app-list command:

$ tsuru app-list
+-------------+-------------------------+---------+--------+
| Application | Units State Summary     | Address | Ready? |
+-------------+-------------------------+---------+--------+
| blog        | 0 of 0 units in-service |         | No     |
+-------------+-------------------------+---------+--------+

Once your app is ready, you will be able to deploy your code, e.g.:

$ tsuru app-list
+-------------+-------------------------+-------------+--------+
| Application | Units State Summary     | Address     | Ready? |
+-------------+-------------------------+-------------+--------+
| blog        | 0 of 0 units in-service |             | Yes    |
+-------------+-------------------------+-------------+--------+

Application code¶

This document will not focus on how to write a blog with Rails, you can clone the entire source direct from GitHub: https://github.com/tsuru/tsuru-ruby-sample. Here is what we did for the project:

Create the project (rails new blog)
Generate the scaffold for Post (rails generate scaffold Post title:string body:text)

Git deployment¶

When you create a new app, tsuru will display the Git remote that you should use. You can always get it using app-info command:

$ tsuru app-info --app blog
Application: blog
Repository: git@cloud.tsuru.io:blog.git
Platform: ruby
Teams: tsuruteam
Address:

The git remote will be used to deploy your application using git. You can just push to tsuru remote and your project will be deployed:

$  git push git@cloud.tsuru.io:blog.git master
Counting objects: 86, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (75/75), done.
Writing objects: 100% (86/86), 29.75 KiB, done.
Total 86 (delta 2), reused 0 (delta 0)
remote: Cloning into '/home/application/current'...
remote: requirements.apt not found.
remote: Skipping...
remote: /home/application/current /
remote: Fetching gem metadata from https://rubygems.org/.........
remote: Fetching gem metadata from https://rubygems.org/..
#####################################
#          OMIT (see below)         #
#####################################
remote:  ---> App will be restarted, please check its log for more details...
remote:
To git@cloud.tsuru.io:blog.git
 * [new branch]      master -> master

If you get a “Permission denied (publickey).”, make sure you’re member of a team and have a public key added to tsuru. To add a key, use key-add command:

$ tsuru key-add ~/.ssh/id_rsa.pub

You can use git remote add to avoid typing the entire remote url every time you want to push:

$ git remote add tsuru git@cloud.tsuru.io:blog.git

Then you can run:

$ git push tsuru master
Everything up-to-date

And you will be also able to omit the --app flag from now on:

$ tsuru app-info
Application: blog
Repository: git@cloud.tsuru.io:blog.git
Platform: ruby
Teams: tsuruteam
Address: blog.cloud.tsuru.io
Units:
+--------------+---------+
| Unit         | State   |
+--------------+---------+
| 9e70748f4f25 | started |
+--------------+---------+

For more details on the --app flag, see “Guessing app names” section of tsuru command documentation.

Listing dependencies¶

In the last section we omitted the dependencies step of deploy. In tsuru, an application can have two kinds of dependencies:

Operating system dependencies, represented by packages in the package manager of the underlying operating system (e.g.: yum and apt-get);
Platform dependencies, represented by packages in the package manager of the platform/language (in Ruby, bundler).

All apt-get dependencies must be specified in a requirements.apt file, located in the root of your application, and ruby dependencies must be located in a file called Gemfile, also in the root of the application. Since we will use MySQL with Rails, we need to install mysql package using gem, and this package depends on an apt-get package: libmysqlclient-dev, so here is how requirements.apt looks like:

libmysqlclient-dev

And here is Gemfile:

source 'https://rubygems.org'

gem 'rails', '3.2.13'
gem 'mysql'
gem 'sass-rails',   '~> 3.2.3'
gem 'coffee-rails', '~> 3.2.1'
gem 'therubyracer', :platforms => :ruby
gem 'uglifier', '>= 1.0.3'
gem 'jquery-rails'

You can see the complete output of installing these dependencies bellow:

$ git push tsuru master
#####################################
#                OMIT               #
#####################################
remote: Reading package lists...
remote: Building dependency tree...
remote: Reading state information...
remote: The following extra packages will be installed:
remote:   libmysqlclient18 mysql-common
remote: The following NEW packages will be installed:
remote:   libmysqlclient-dev libmysqlclient18 mysql-common
remote: 0 upgraded, 3 newly installed, 0 to remove and 0 not upgraded.
remote: Need to get 2360 kB of archives.
remote: After this operation, 9289 kB of additional disk space will be used.
remote: Get:1 http://archive.ubuntu.com/ubuntu/ quantal/main mysql-common all 5.5.27-0ubuntu2 [13.7 kB]
remote: Get:2 http://archive.ubuntu.com/ubuntu/ quantal/main libmysqlclient18 amd64 5.5.27-0ubuntu2 [949 kB]
remote: Get:3 http://archive.ubuntu.com/ubuntu/ quantal/main libmysqlclient-dev amd64 5.5.27-0ubuntu2 [1398 kB]
remote: Fetched 2360 kB in 2s (1112 kB/s)
remote: Selecting previously unselected package mysql-common.
remote: (Reading database ... 41063 files and directories currently installed.)
remote: Unpacking mysql-common (from .../mysql-common_5.5.27-0ubuntu2_all.deb) ...
remote: Selecting previously unselected package libmysqlclient18:amd64.
remote: Unpacking libmysqlclient18:amd64 (from .../libmysqlclient18_5.5.27-0ubuntu2_amd64.deb) ...
remote: Selecting previously unselected package libmysqlclient-dev.
remote: Unpacking libmysqlclient-dev (from .../libmysqlclient-dev_5.5.27-0ubuntu2_amd64.deb) ...
remote: Setting up mysql-common (5.5.27-0ubuntu2) ...
remote: Setting up libmysqlclient18:amd64 (5.5.27-0ubuntu2) ...
remote: Setting up libmysqlclient-dev (5.5.27-0ubuntu2) ...
remote: Processing triggers for libc-bin ...
remote: ldconfig deferred processing now taking place
remote: /home/application/current /
remote: Fetching gem metadata from https://rubygems.org/..........
remote: Fetching gem metadata from https://rubygems.org/..
remote: Using rake (10.1.0)
remote: Using i18n (0.6.1)
remote: Using multi_json (1.7.8)
remote: Using activesupport (3.2.13)
remote: Using builder (3.0.4)
remote: Using activemodel (3.2.13)
remote: Using erubis (2.7.0)
remote: Using journey (1.0.4)
remote: Using rack (1.4.5)
remote: Using rack-cache (1.2)
remote: Using rack-test (0.6.2)
remote: Using hike (1.2.3)
remote: Using tilt (1.4.1)
remote: Using sprockets (2.2.2)
remote: Using actionpack (3.2.13)
remote: Using mime-types (1.23)
remote: Using polyglot (0.3.3)
remote: Using treetop (1.4.14)
remote: Using mail (2.5.4)
remote: Using actionmailer (3.2.13)
remote: Using arel (3.0.2)
remote: Using tzinfo (0.3.37)
remote: Using activerecord (3.2.13)
remote: Using activeresource (3.2.13)
remote: Using coffee-script-source (1.6.3)
remote: Using execjs (1.4.0)
remote: Using coffee-script (2.2.0)
remote: Using rack-ssl (1.3.3)
remote: Using json (1.8.0)
remote: Using rdoc (3.12.2)
remote: Using thor (0.18.1)
remote: Using railties (3.2.13)
remote: Using coffee-rails (3.2.2)
remote: Using jquery-rails (3.0.4)
remote: Installing libv8 (3.11.8.17)
remote: Installing mysql (2.9.1)
remote: Using bundler (1.3.5)
remote: Using rails (3.2.13)
remote: Installing ref (1.0.5)
remote: Using sass (3.2.10)
remote: Using sass-rails (3.2.6)
remote: Installing therubyracer (0.11.4)
remote: Installing uglifier (2.1.2)
remote: Your bundle is complete!
remote: Gems in the groups test and development were not installed.
remote: It was installed into ./vendor/bundle
#####################################
#                OMIT               #
#####################################
To git@cloud.tsuru.io:blog.git
   9515685..d67c3cd  master -> master

Running the application¶

As you can see, in the deploy output there is a step described as “Restarting your app”. In this step, tsuru will restart your app if it’s running, or start it if it’s not. But how does tsuru start an application? That’s very simple, it uses a Procfile (a concept stolen from Foreman). In this Procfile, you describe how your application should be started. Here is how the Procfile should look like:

web: bundle exec rails server -p $PORT -e production

Now we commit the file and push the changes to tsuru git server, running another deploy:

$ git add Procfile
$ git commit -m "Procfile: added file"
$ git push tsuru master
#####################################
#                OMIT               #
#####################################
remote:  ---> App will be restarted, please check its log for more details...
remote:
To git@cloud.tsuru.io:blog.git
   d67c3cd..f2a5d2d  master -> master

Now that the app is deployed, you can access it from your browser, getting the IP or host listed in app-list and opening it. For example, in the list below:

$ tsuru app-list
+-------------+-------------------------+---------------------+--------+
| Application | Units State Summary     | Address             | Ready? |
+-------------+-------------------------+---------------------+--------+
| blog        | 1 of 1 units in-service | blog.cloud.tsuru.io | Yes    |
+-------------+-------------------------+---------------------+--------+

Using services¶

Now that your app is not running with success because the rails can’t connect to MySQL. That’s because we add a relation between your rails app and a mysql instance. To do it we must use a service. The service workflow can be resumed to two steps:

Create a service instance
Bind the service instance to the app

But how can I see what services are available? Easy! Use service-list command:

$ tsuru service-list
+----------------+-----------+
| Services       | Instances |
+----------------+-----------+
| elastic-search |           |
| mysql          |           |
+----------------+-----------+

The output from service-list above says that there are two available services: “elastic-search” and “mysql”, and no instances. To create our MySQL instance, we should run the service-add command:

$ tsuru service-add mysql blogsql
Service successfully added.

Now, if we run service-list again, we will see our new service instance in the list:

$ tsuru service-list
+----------------+-----------+
| Services       | Instances |
+----------------+-----------+
| elastic-search |           |
| mysql          | blogsql   |
+----------------+-----------+

To bind the service instance to the application, we use the bind command:

$ tsuru bind blogsql
Instance blogsql is now bound to the app blog.

The following environment variables are now available for use in your app:

- MYSQL_PORT
- MYSQL_PASSWORD
- MYSQL_USER
- MYSQL_HOST
- MYSQL_DATABASE_NAME

For more details, please check the documentation for the service, using service-doc command.

As you can see from bind output, we use environment variables to connect to the MySQL server. Next step is update conf/database.yml to use these variables to connect in the database:

production:
  adapter: mysql
  encoding: utf8
  database: <%= ENV["MYSQL_DATABASE_NAME"] %>
  pool: 5
  username: <%= ENV["MYSQL_USER"] %>
  password: <%= ENV["MYSQL_PASSWORD"] %>
  host: <%= ENV["MYSQL_HOST"] %>

Now let’s commit it and run another deploy:

$ git add conf/database.yml
$ git commit -m "database.yml: using environment variables to connect to MySQL"
$ git push tsuru master
Counting objects: 7, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (4/4), done.
Writing objects: 100% (4/4), 535 bytes, done.
Total 4 (delta 3), reused 0 (delta 0)
remote:
remote:  ---> Tsuru receiving push
remote:
remote:  ---> Installing dependencies
#####################################
#               OMIT                #
#####################################
remote:
remote:  ---> Restarting your app
remote:
remote:  ---> Deploy done!
remote:
To git@cloud.tsuru.io:blog.git
   ab4e706..a780de9  master -> master

Now if we try to access the admin again, we will get another error: “Table ‘blogsql.django_session’ doesn’t exist”. Well, that means that we have access to the database, so bind worked, but we did not set up the database yet. We need to run rake db:migrate in the remote server. We can use run command to execute commands in the machine, so for running rake db:migrate we could write:

$ tsuru run -- RAILS_ENV=production bundle exec rake db:migrate
==  CreatePosts: migrating ====================================================
-- create_table(:posts)
   -> 0.1126s
==  CreatePosts: migrated (0.1128s) ===========================================

Deployment hooks¶

It would be boring to manually run rake db:migrate after every deployment. So we can configure an automatic hook to always run before or after the app restarts.

Tsuru parses a file called app.yaml and runs restart hooks. As the extension suggests, this is a YAML file, that contains a list of commands that should run before and after the restart. Here is our example of app.yaml:

hooks:
  restart:
    before-each:
      - RAILS_ENV=production bundle exec rake db:migrate

For more details, check the hooks documentation.

Tsuru will look for the file in the root of the project. Let’s commit and deploy it:

$ git add app.yaml
$ git commit -m "app.yaml: added file"
$ git push tsuru master
#####################################
#                OMIT               #
#####################################
To git@cloud.tsuru.io:blog.git
   a780de9..1b675b8  master -> master

It is necessary to compile de assets before the app restart. To do it we can use the rake assets:precompile command. Then let’s add the command to compile the assets in app.yaml:

hooks:
  restart:
    before:
      - RAILS_ENV=production bundle exec rake assets:precompile

$ git add app.yaml
$ git commit -m "app.yaml: added file"
$ git push tsuru master
#####################################
#                OMIT               #
#####################################
To git@cloud.tsuru.io:blog.git
   a780de9..1b675b8  master -> master

It’s done! Now we have a Rails project deployed on tsuru, using a MySQL service.

Now we can access your blog app in the URL http://blog.cloud.tsuru.io/posts/.

Going further¶

For more information, you can dig into tsuru docs, or read complete instructions of use for the tsuru command.