Dokku Rails 6

Deploying Rails 6.0.1 app on Digitalocean VPS using Dokku 0.19.10. Following Alan Vardy's blog post and video presentation on Youtube. Dokku also uses dokku-postgres to handle the database.

app versions are indicated at the time of this writing (Dec. 9, 2019)

Creating a Dokku Droplet on Digitalocean

1. Obtain a domain name

For testing I used Freenom which is you guessed, free domain hosting. Alan uses Namecheap and is proud about it.

2. Signup for Digitalocean

One of the best and cheapest VPS hosting you can find out there.

3. Create a Droplet on Digitalocean

You can create a droplet (virtual private server) with Dokku pre-installed! When creating a droplet, select the Marketplace and look for Dokku, add your SSH keys and for testing you can select the lowest and cheapest plan.

4. Go to your server's IP and follow the web installer

Navigate to your droplet's IP address which will be listed in digitalocean. You will need to paste in your public ssh key, then make sure to check "Virtual host naming" for your apps. It means that if you create an app called myapp, it will be accessible at myapp.mydomain.com

5. Put your domain on Hostname field

This will be important as dokku will generate url based on what you put on Hostname field such as myapp.mydomain.com where mydomain.com is the hostname. It is possible to change hostnames after installation but I would just recommend to rebuild the app completely if you are changing hostnames.

Creating a Dokku app

5. SSH onto your server

ssh [email protected]

6. Update everything (Digital Ocean's droplets will not be completely up to date, and Dokku can easily be a few versions behind)

apt update && apt upgrade

7. Create the app

dokku apps:create yourappname

8. Install Postgres, create and link database

dokku plugin:install https://github.com/dokku/dokku-postgres.git
dokku postgres:create yourdbname
dokku postgres:link yourdbname yourappname

9. Create a swap file to help out on the ram front. You will only see output after the 3rd line.

fallocate -l 2G /swapfile
chmod 600 /swapfile
mkswap /swapfile
swapon /swapfile

10. Open fstab with Vim

vi /etc/fstab

11. Add this line at the bottom

/swapfile none swap sw 0 0

• Press "i" to enter edit mode.
• Press "esc" after finish adding the line to exit edit mode
• Press "shift+:" then type "wq" to write file and quit editor

12. Configure Digitalocean DNS Click Add domain on digitalocean then add the domain you have got freely on freenom or bought on namecheap. Create 'A' record for your domain:

Type	Hostname	Value
A	yourdomain.com	(select your droplet)

Rails app

1. Creating the app

rails new yourrailsapp --database=postgresql

2. Navigate to your app directory and generate a controller

cd awesomeapp
rails generate controller Static index

• Here we got a controller name Static with index method
• Add something to that index page in app/views
• then add the route to config/routes.rb

root 'static#index'

3. Automatic Migrations This one just runs rails db:migrate automatically. Create app.json in the root directory of your app

{
  "name": "awesomeapp",
  "description": "My awesome Rails app, running on Dokku!",
  "keywords": [
    "dokku",
    "rails"
  ],
  "scripts": {
    "dokku": {
      "postdeploy": "bundle exec rails db:migrate"
    }
  }
}

4. Add checks This feature is rather nice, it makes Dokku check to make sure that your freshly uploaded code actually starts up before switching over to it! Create a file called CHECKS in the root of your project directory

# CHECKS

WAIT=10  
ATTEMPTS=6  
/check.txt it_works

• Add the following route to config/routes.rb

get '/check.txt', to: proc {[200, {}, ['it_works']]}

• And it will make a call to that route when it starts up your new code, thereby ensuring that the new server actually started.

5. Add your secrets file

# config/secrets.yml
production:
  secret_key_base: <%= ENV["SECRET_KEY_BASE"] %>

• on Rails 6 we now also have encryption for the secret key base file in the form of the master.key file which decrypts the file called credentials.yml.enc that holds your secret_key_base
• the 2 file will be generated upon executing rails new command at the start of creating your rails app.

# config/database.yml
production:
  adapter: postgresql
  secret_key_base: <%= Rails.application.credentials.dig(:secret_key_base) %>
  rails_master_key: <%= ENV['RAILS_MASTER_KEY'] %>
  encoding: unicode
  pool: 5 

• It is recommended not to include your master.key when pushing to repo. By default it is included on .gitignorefile
• Without the master.key, the application won't run
• Locate ythe master key on same directory as credentials.yml.enc config/master.key then copy the hash string
• Since it will not be included when pushing to our dokku vps, we will save it on ENV variable instead and access it from the variable. ssh to your droplet then run the following dokku command:

dokku config:set yourappname RAILS_MASTER_KEY=thehashstringfromyourmasterkeyfile

6. Set up Puma correctly If you are using Rails 6, take a look at this post to save yourself some headache in getting Puma up and running.

7. Add remote repository Navigate to your yourrailsapp project directory and add the repository

git remote add dokku [email protected]:yourappname

8. You can now push your code with

git add .
git commit -m 'Initialize repo'
git push dokku master

Free SSL with Let's Encrypt

Let's Encrypt provides free SSL certificates. You can find more complete instructions and explanations here.

1. SSH onto your server

ssh [email protected]

2. Install Let's Encrypt

dokku plugin:install https://github.com/dokku/dokku-letsencrypt.git

• Update if it was already installed

dokku plugin:update letsencrypt

3. Set your email address (note that you need to change MYAPP and [email protected])

dokku config:set --no-restart awesomeapp [email protected]

4. Turn it on

dokku letsencrypt yourappname

5. Set up auto-renewal with a cronjob

dokku letsencrypt:cron-job --add