Setting up a simple deploy process using distillery and git deploy

One of the tools I love from the ruby world is git-deploy. It is awesome for what it does. And, my current setup is a simple single phoenix server. So, using git-deploy makes sense.

Here are the steps to set it up for posterity.

Install git-deploy on your local computer. You need ruby for this to work: gem install git-deploy

I am assuming that you have an ubuntu based server for this tutorial and that the name of the app is sprymesh. You need to install esl-erlang, elixir and nodejs on the server.

# install erlang and elixir
wget https://packages.erlang-solutions.com/erlang-solutions_1.0_all.deb && sudo dpkg -i erlang-solutions_1.0_all.deb
sudo apt-get update
# make and build-essential are needed by a few apps
sudo apt-get install esl-erlang elixir make build-essential
mix local.hex
mix local.rebar
mix local.rebar3
# install nodejs
curl -sL https://deb.nodesource.com/setup_8.x | sudo -E bash -
sudo apt-get install -y nodejs

Install postgresql on the server, if it is not already present.

Create a user specific account on the server.

sudo mkdir -p /opt/www
# name of my user account is sprymesh
sudo useradd --home /opt/www/sprymesh --create-home --shell /bin/bash sprymesh
# create the database user
sudo -u postgres createuser --echo --no-createrole --no-superuser --createdb sprymesh
# setup the password for the above pg user and tweak the pg_hba.conf if needed
sudo -u sprymesh createdb sprymesh_prod
# test by opening a psql connection
psql --username=sprymesh --password sprymesh_prod

Add distillery to your deps
```
{:distillery, "~> 1.4"},
```
Create a rel/config.exs
```
mix release.init
```
Create a git tag with the value ‘v1.0’. This is used to build an incrementing version number for our release.
```
git tag --annotate --message 'First version' v1.0
```

Tweak your mix.exs’s version

def project do
  [app: :danny_web,
   version: app_version(),
  # ...
end

defp app_version do
  # get git version
  {ts, 0} = System.cmd("git", ~w[describe])
  _git_version = String.strip(ts) |> String.split("-") |> Enum.take(2) |> Enum.join(".") |> String.replace_leading("v", "")
end

Add your ssh key to ~sprymesh/.ssh/authorized_keys

Create your git deploy setup

git remote add prod "sprymesh@sprymesh.com:/opt/www/sprymesh"
git deploy setup -r prod
git deploy init

Create a /opt/www/sprymesh/env file containing your env vars/secrets

MIX_ENV=prod
SM_APPSIGNAL=....
DATABASE_URL=ecto://un:pw@localhost:5432/db_prod
PORT=4000

Change deploy/before_restart to something like below

#!/bin/bash -e

# source env so that we have all secrets setup
source <(sed 's/^/export /' ./env)

# deps are needed
mix deps.get

# build the js files
(cd assets && npm install --no-progress && ./node_modules/brunch/bin/brunch build --production)

# build release
mix phoenix.digest
mix release

Change deploy/restart to

#!/bin/bash

echo "restarting sprymesh"
sudo systemctl stop sprymesh.service
sudo systemctl start sprymesh.service
echo "finished restarting sprymesh"

Create a systemd init script: Add the following to /etc/systemd/system/sprymesh.service and run the following command

[Unit]
Description=Sprymesh phoenix app
After=network.target

[Service]
User=sprymesh
WorkingDirectory=/opt/www/sprymesh
EnvironmentFile=/opt/www/sprymesh/env
ExecStart=/opt/www/sprymesh/_build/prod/rel/sprymesh/bin/sprymesh foreground
ExecStop=/opt/www/sprymesh/_build/prod/rel/sprymesh/bin/sprymesh stop
Restart=always
StandardInput=null
StandardOutput=syslog
StandardError=syslog
SyslogIdentifier=%n
KillMode=process
TimeoutStopSec=5

Reload the systemd scripts. Run the following commands:

sudo systemctl daemon-reload
sudo systemctl enable sprymesh.service

Push our code to the server. Push to prod

git push prod master
git push prod --tags

Add a config/prod.secret.exs on the server, tweak it to include all your info. In my setup, I am passing the db info via DATABASE_URL env variable.
```
use Mix.Config

config :danny_web, Danny.Repo,
  adapter: Ecto.Adapters.Postgres,
  pool_size: 10
```
Add the following to your /etc/sudoers file. You need this so that the app user sprymesh can restart its’ own service

User_Alias SPRYMESH_APP = sprymesh Cmnd_Alias SM_PROCESS_CTL = /bin/systemctl daemon-reload, /bin/systemctl start sprymesh.service, /bin/systemctl stop sprymesh.service, /bin/systemctl restart sprymesh.service SPRYMESH_APP ALL = NOPASSWD: SM_PROCESS_CTL
Finally login to the server and run the following commands, to do the first deploy

sudo su sprymesh ~/deploy/after_push

The source for this is hosted at https://github.com/12startupsin12months/blog.12startupsin12months.in/blob/master/_posts/2017-06-27-setting-up-a-simple-deploy-process-using-distillery-and-git-deploy.md If you find an improvement, send a PR :)