discourse/docs/HEROKU.md

Basic Heroku deployment

This guide takes you through the steps for deploying Discourse to the Heroku cloud application platform. If you're unfamiliar with Heroku, read this first. The basic deployment of Discourse requires several services that will cost you money. In addition to the 750 free Dyno hours provided by Heroku, the application requires one additional process to be running for the Sidekiq queue ($34 monthly), and a Redis database plan that supports a minimum of 2 databases (average $10 monthly).

For details on how to reduce the monthly cost of your application, see Advanced Heroku deployment.

Download and configure Discourse

1. If you haven't already, download Discourse and create a new branch for your Heroku configuration.

    git clone git@github.com:discourse/discourse.git
    cd discourse
    git checkout -b heroku
   

2. Modify the redis.yml file to use the environment variable provided by Heroku and the Redis provider of your choice.

   config/redis.yml

    - uri: <%= uri = URI.parse(ENV['SET_REDIS_PROVIDER_URL'] || "redis://localhost:6379") %>
    + uri: <%= uri = URI.parse(ENV['OPENREDIS_URL'] || "redis://localhost:6379") %>
   

3. Comment out or delete config/redis.yml from .gitignore. We want to include redis.yml when we push to Heroku.

   .gitignore

   - config/redis.yml
   + # config/redis.yml
   

4. Specify the Ruby version at the top of the Gemfile.

   Heroku defaults to ruby 1.9.2, but Discourse requires a minimum of ruby 1.9.3.

   Gemfile

     source 'https://rubygems.org'
   
   + ruby "2.0.0"
     ...
   

5. Commit your changes.

    git add .
    git commit -m "ready for Heroku"
   

Deploy to Heroku

1. Create the heroku app. This automatically creates a git remote called heroku.

    heroku create your-app-name
   

2. Add a suitable Redis provider from Heroku add-ons, (this service will cost you money).

    heroku addons:add openredis:micro
   

3. Add the Heroku Scheduler add-on, this saves us from running a separate clock process, reducing the cost of the app.

    heroku addons:add scheduler:standard
   

4. Generate a secret token in the terminal.

    rake secret
   

5. Push the secret to the stored heroku environment variables, this will now be available to your app globally.

    heroku config:add SECRET_TOKEN=<generated secret>
   

6. Precompile assets.

   There are two options for precompilation. Either precompile locally, before each deploy or enable Heroku's experimental user-env-compile feature and Heroku will precompile your assets for you.

   1. Option 1: Enable user-env-compile.

       heroku labs:enable user-env-compile
      

      Caveat: If you should need to change or add environment variables for any reason, you will need to remove user-env-compile, then re-apply it after making the changes. This will then require you to make a commit, even if it is an empty commit, and then push to Heroku for the changes to be applied.

      If needed, you can remove the user-env-compile option with this command.

       heroku labs:disable user-env-compile
      

   2. Option 2: Precompile locally.

       bundle exec rake assets:precompile
      

      Notice: We don't use Foreman to start precompilation, as this would precompile in the development environment. Instead, rake assets:precompile runs in the production environment by default, as it should.

      If Rails complains that the SECRET_TOKEN is not set, you can pass this to the environment by prefixing it to the rake method call.

       SECRET_TOKEN=5310bc16ef6ecfd0...  bundle exec rake assets:precompile
      

      Tip: OSX/Linux users can set/unset environment variables in their shell.

       # Set var
       export SECRET_TOKEN=5310bc16ef6ecfd0...
       # Unset var
       unset SECRET_TOKEN
      

7. Push your heroku branch to Heroku.

    git push heroku heroku:master
   

8. Migrate and seed the database.

    heroku run rake db:migrate db:seed_fu
   

   You should now be able to visit your app at http://<your-app-name>.herokuapp.com

Configure the deployed application

1. Log into the app, using your preferred auth provider.

2. Connect to the Heroku console to make the first user an Admin.

    heroku run console
   

3. Enter the following commands.

    u = User.first
    u.admin = true
    u.approved = true
    u.save

4. In Discourse admin settings, set force_hostname to your applications Heroku domain.

   This step is required for Discourse to properly form links sent with account confirmation emails and password resets. The auto detected application url would point to an Amazon AWS instance.

   Since you can't log in yet, you can set force_hostname in the console.

   SiteSetting.create(:name => 'force_hostname', :data_type =>1, :value=>'yourappnamehere.herokuapp.com')

5. Provision the Heroku Scheduler.

This will allow Heroku Scheduler to cue up tasks rather than running a separate clock process. In the Heroku dashboard, select your app, then click on Heroku Scheduler Standard under your Add-ons.

Next, add a Job for each of the following:

    TASK                        FREQUENCY         NEXT RUN
    ------------------------------------------------------

    rake enqueue_digest_emails  Daily                06:00

    rake category_stats         Daily                04:00

    rake periodical_updates     Every 10 minutes     --:--

    rake version_check          Daily                01:00

6. Start Sidekiq.

   In the Heroku dashboard, select your app and you will see the separate processes that have been created for your application under Resources. You will only need to start the sidekiq process for your application to run properly. The clock process is covered by Heroku Scheduler, and you can even remove this from the Procfile before deploying if you so wish. The worker process has been generated as a Rails default and can be ignored. As you can see the Sidekiq process costs $34 monthly to run. If you want to reduce this cost, check out Advanced Heroku deployment.

   Click on the check-box next to the Sidekiq process and click Apply Changes

   Your Discourse application should now be functional. However, you will still need to configure mail functionality and file storage for uploaded images. For some examples of doing this within Heroku, see Heroku add-on examples.

Running the application locally

Using Foreman to start the application allows you to mimic the way the application is started on Heroku. It loads environment variables via the .env file and instantiates the application using the Procfile. In the .env sample file, we have set RAILS_ENV='development', this makes the Rails environment variable available globally, and is required when starting this application using Foreman.

First, save the file .env.sample as .env

.env

RAILS_ENV='development'

Foreman commands:

Create the database

bundle exec foreman run rake db:create

Migrate and seed the database

bundle exec foreman run rake db:migrate db:seed_fu

Start the application using Foreman

bundle exec foreman start

Use Rails console, with pry

bundle exec foreman run rails console

Heroku add-on examples

Email

Mandrill example

1. Add the Mandrill by MailChimp add-on from the Heroku add-ons page, or install from the command line using:

    heroku addons:add mandrill:starter
   

2. Configure the smtp settings in the production environment config file.

   config/environments/production.rb

   - config.action_mailer.delivery_method = :sendmail
   - config.action_mailer.sendmail_settings = {arguments: '-i'}
   
   + config.action_mailer.delivery_method = :smtp
   + config.action_mailer.smtp_settings = {
   +     :port =>           '587',
   +     :address =>        'smtp.mandrillapp.com',
   +     :user_name =>      ENV['MANDRILL_USERNAME'],
   +     :password =>       ENV['MANDRILL_APIKEY'],
   +     :domain =>         'heroku.com',
   +     :authentication => :plain
   + }
   

Advanced Heroku deployment

Autoscaler

Adding the Autoscaler Gem can help you better manage the running cost of your application by scaling down the Sidekiq worker process when not in use. This could save up to $34 per month depending on your usage levels.

Whilst this Gem has the potential to save you money, it in no way guarantees it. Use of this Gem should be combined with careful monitoring of your applications processes and usage alerts where necessary.

1. Push your Heroku API key and app name to Heroku.

    heroku config:add HEROKU_API_KEY=<get your API key from acct settings> HEROKU_APP=<your app name>
   

2. Add the Autoscaler Gem to the Gemfile.

   Gemfile

   gem 'autoscaler', require: false
   

3. Modify the Sidekiq config file to use the Autoscaler middleware in production.

   config/initializers/sidekiq.rb

   sidekiq_redis = { url: $redis.url, namespace: 'sidekiq' }
   
   if Rails.env.production? 
   
     require 'autoscaler/sidekiq'
     require 'autoscaler/heroku_scaler'
   
   	Sidekiq.configure_server do |config| 
   	  config.redis = sidekiq_redis
   	  config.server_middleware do |chain|
   	    chain.add(Autoscaler::Sidekiq::Server, Autoscaler::HerokuScaler.new('sidekiq'), 60)
   	  end
   	end
   
   
   	Sidekiq.configure_client do |config| 
   	  config.redis = sidekiq_redis
   	  config.client_middleware do |chain|
   	    chain.add Autoscaler::Sidekiq::Client, 'default' => Autoscaler::HerokuScaler.new('sidekiq')
   	  end
   	end
   
   else
   
     Sidekiq.configure_server { |config| config.redis = sidekiq_redis }
     Sidekiq.configure_client { |config| config.redis = sidekiq_redis }
   
   end