Elixir (Phoenix) Nix Example

Example repo to show off how I use Nix as build environment for Elixir / Phoenix projects.
Important Nix stuff is located within default.nix & pkg/ folder.

Setup

This repo provides an easy environment setup by the usage of Nix.
Nix currently runs on Linux and macOS.

• Getting Nix

By using Nix, beside Nix nothing else needs to be installed manually.

Windows
Recommended also using Nix within a Linux Virtual Machine or WSL 2.

Manual Setup

For maintaining simplicity, instructions for a manual setup isn't part of this readme.
Anyway, required dependencies:

• Elixir (& Erlang)
• PostgreSQL
• Node.js

Development

For convenience an alias configuration exists for some of the following shell commands.

Environment

# Enter shell w/ development environment (no database)
# Alias: `app-env`
nix-shell --pure -A env

# Run commands without shell
nix-shell --pure -A env --run <command>

# Run commands in interactive shell
nix-shell --pure -A env --cmd <command>

# Enter shell w/ development environment and temporary PostgreSQL database
nix-shell --pure -A env_with_db

# Running all tests
# Alias: `app-test`
nix-shell --pure -A env_with_db --argstr MIX_ENV test --run 'mix test'

Basics commands for working with Elixir / Phoenix

# Get Elixir mix deps
mix deps.get

# Get JS packages
npm install --prefix assets

# Start Phoenix server
mix phx.server

# Start Elixir application
mix run --no-halt

# Enter IEx
iex -S mix

# Run tests
mix test

Build

# mix deps
nix-build -A mix_deps --option sandbox relaxed

# JS packages
nix-build -A node_modules --option sandbox relaxed

# Compile
nix-build -A mix_build --option sandbox relaxed

# Compile cacheable -> .nix/_build
nix-shell --pure -A env --command 'mix compile'

# Generate docs using `mix docs`
nix-build -A docs --option sandbox relaxed

# Build procution release using `mix release`
nix-build -A release --argstr MIX_ENV prod --option sandbox relaxed

Maintenance commands

# Update pinned Nix pkgs
elixir pkg/scripts/pkgs_update.exs

# Check outdated Mix deps & NPM packages
mix hex.outdated
npm outdated --prefix assets

# Update Mix deps & NPM packages
mix deps.update --all
npm update --prefix assets

# Removed unused deps from mix.lock
mix deps.clean --unlock --unused

Aliases

# Load aliases into your shell
# You could also source this in your .profile
. pkg/scripts/alias.sh

Working with aliases

# List
alias

# Remove
unalias alias_name

# Remove all
unalias -a

direnv

direnv let's you automatically load environment variables per directory defined in .envrc.

Working with direnv

# Install via Nix
nix-env -iA nixpkgs.direnv

# Setup hook
# Add the following to your .profile
eval "$(direnv hook bash)"