Deploying to Dokku

# Prerequisites

You will need a server with Dokku installed and SSH access. See the Dokku Getting Started guide for more details.

# Setting up the Dokku configuration

SSH into your server to get it ready for deployment.

ssh root@ip

In the following commands replace app.example.com with your domain or subdomain. Replace exampledb with your preferred database name.

This will create the initial app container in Dokku, create the database, and link them both together. The last three lines set environment variables for the Lucky app. The first will tell Lucky to run the app in production mode, the second will tell Lucky what the app URL is, and the third will tell the app to run on port 5000 which Dokku will connect with Nginx to expose to the world.

dokku apps:create app.example.com
# install the postgres plugin
# plugin installation requires root, hence the user change
sudo dokku plugin:install https://github.com/dokku/dokku-postgres.git
dokku postgres:create exampledb
dokku postgres:link exampledb app.example.com
dokku config:set app.example.com LUCKY_ENV=production
dokku config:set app.example.com APP_DOMAIN=app.example.com
dokku config:set app.example.com PORT=5000

There’s a few more configuration details that need to be set. First, you’ll need to tell Lucky the database details that are set in Dokku. Run the below command to get the database URL.

dokku postgres:info exampledb

Set the DATABASE_URL environment variable from the above output.

dokku config:set app.example.com DATABASE_URL=postgres://...

Next, Lucky needs a secret key environment variable. In your app directory on your local machine run the following command which will generate a secure key.

lucky gen.secret_key

Then, back on your remote Dokku server add it to the SECRET_KEY_BASE environment variable.

dokku config:set app.example.com SECRET_KEY_BASE=...

If you’re planning to send emails through the app you’ll also need to set SEND_GRID_KEY key, otherwise, change config/email.cr to use Carbon::DevAdapter.new in production (and make sure to commit!)

dokku config:set app.example.com SEND_GRID_KEY=...

Your server is almost ready for deployment. If you’re using a server with 2GB of RAM or less, you’ll need to set up a Swap. Without it the deployment process will most likely run into memory issues. Checkout this tutorial for setting up a Swap. A 1G Swap should be more than enough.

# Ready the app for deployment

Back in your local app add a new file called .buildpacks with the following contents. This is the same buildpacks used for the Heroku deployment.

https://github.com/heroku/heroku-buildpack-nodejs
https://github.com/luckyframework/heroku-buildpack-crystal

Make sure the web service in the Procfile is correctly configured:

web: ./app
# ...

And add the CHECKS file with the following contents at the root of your project, to speed up post-deploy checks:

WAIT=5

# First deployment

Make a new commit. Finally you’re ready to deploy. Run the following commands locally. The first will add your server as a remote origin for your git repo. The second will push the code to the server.

git remote add dokku dokku@ip:app.example.com
git push dokku main

# Set up SSL

Dokku lets you easily set up a Lets Encrypt SSL certificate. Run the following commands to do so

dokku config:set --no-restart app.example.com DOKKU_LETSENCRYPT_EMAIL=your.email@example.com
dokku letsencrypt app.example.com

That’s all there is to it! Each time you push to your Dokku server your app will update and migrations will be ran automatically.