How to deploy your Phoenix side projects (without a PaaS)

There are many great Platform as a Service (PaaS) providers for Phoenix. Render, and Fly.io especially, and they have great documentation for getting up and running. PaaS providers have lots of benefits, including ease of deployments, managed databases with automatic backups, and more. But using a plain Virtual Private Server (VPS) can get you more power for a lot less money. This is especailly true if you are running multiple apps.

In this post, we are going to go from (almost) zero to deployment using Hetzner, but you can follow along using other cloud providers, such as Linode, Digital Ocean, or even AWS or GCP. I chose Hetzner for their great reviews, and low price.

I am assuming familiarity with the command line and git. If you get stuck at point, just shoot me an email.

Get a server

Create an account at https://cloud.hetzner.com, and create a server in a region near you. I chose Ashburn, VA, Ubuntu 22.04, Standard, and the cheapest option CPX11. I already had an ssh set up (for github, so I uploaded the public key to Hetzner and used that).

After you click “Create and Buy Now”, your server will take a few seconds to provision. Once it is done provisioning, take note of the IP address. We will use it later.

Setup DNS

This could really be done at the end, but since DNS propagation could take some time, better to just get it out of the way early. I use namecheap, so I am going to set up a A record, pointing phoenix.joseph.wtf to the IP address of my server from Hetzner.

Phoenix Application Set Up

If Elixir and Phoenix are not already installed on your machine, install them now. Instructions.

# Your machine
yes | mix phx.new my_app --verbose
cd my_app
git init
git add -A
git commit -am "init"

Create a repo in your git repository of choice, such as Github, or Gitlab.

Now here is the real magic.

# Your machine
mix phx.gen.release --docker # 🤯

This created a few files, the most important of which is the Dockerfile .

Lets also create a file called docker-compose.yaml

# docker-compose.yaml
services:
  web:
    build: .
    env_file: ".env"
    ports:
      - "4000:4000"
    depends_on:
      - "postgres"
    restart: "always"
  postgres:
    image: "postgres:15.2-bullseye"
    env_file: ".env"
    volumes:
      - "postgres:/var/lib/postgresql/data"
    restart: "always"
  migration:
    build: .
    env_file: ".env"
    depends_on:
      - web
      - postgres
    command: bin/migrate
    restart: "no"
  caddy:
    image: caddy:2.6.4-alpine
    restart: unless-stopped
    command: caddy reverse-proxy --from https://phoenix.joseph.wtf:443 --to http://web:4000
    ports:
      - 80:80
      - 443:443
    volumes:
      - caddy:/data
    depends_on:
      - web
volumes:
  postgres: {}
  caddy: {}

Next, create a .env file, which will hold your applicaton secrets.

You can generate a secret key base with mix phx.gen.secret. Since this file is ignored by git, you’ll want to add it (with different secrets) to both your development machine, and the prod machine.

# .env
SECRET_KEY_BASE=<run mix phx.gen.secret>
PHX_HOST="phoenix.joseph.wtf"
POSTGRES_USER=my_app
POSTGRES_PASSWORD=password
POSTGRES_DB=my_app
DATABASE_URL=postgres://${POSTGRES_USER}:${POSTGRES_PASSWORD}@postgres:5432/${POSTGRES_DB}

Now that we’ve created our release, and docker-compose.yaml file, we can commit.

# Your machine
# make sure .env is ignored by git.
git add -A
git commit -m "Dockerize"
git push

Now, bring it all together on your development machine. Run docker-compose up --build. Because we are forwarding port 4000 from Docker, we just visit https://localhost:4000 to see our app running in Docker.

Ready, Set, Deploy

Setting up our prod machine

# Your machine
# Replace id_ed25519 with your SSH private key,
# and 5.161.109.211 with the IP address of the server you provisioned
ssh -i ~/.ssh/id_ed25519 root@<your_ip>

After this command, you will be in a terminal prompt on your production machine.

First install docker per the most up to date instructions on docs.docker.com

# Prod machine
sudo apt-get update
sudo apt-get install \
    ca-certificates \
    curl \
    gnupg \
    lsb-release

sudo mkdir -m 0755 -p /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg

echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu \
  $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

sudo apt-get update

sudo apt-get install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

# Prod machine
# replace with the URL of your repo
git clone https://github.com/joseph-lozano/my_app
cd my_app
# create a .env file with your application secrets, just like on the development machine
vi .env

After all that is done, just run

# Prod machine
docker-compose up --build -d