Heroku Buildpack for Elixir
- Easy configuration with
- Use prebuilt Elixir binaries
- Allows configuring Erlang
- If your app doesn't have a Procfile, default web task
mix run --no-haltwill be run.
- Consolidates protocols
- Hex and rebar support
- Caching of Hex packages, Mix dependencies and downloads
- Compilation procedure hooks through
- Erlang - Prebuilt packages (17.5, 17.4, etc)
- The full list of prebuilt packages can be found here: https://github.com/HashNuke/heroku-buildpack-elixir-otp-builds/blob/master/otp-versions
- Note: if a version you want is missing then you can create a PR that adds it
- Elixir - Prebuilt releases (1.0.4, 1.0.3, etc) or prebuilt branches (master, v1.7, etc)
Note: you should choose an Elixir and Erlang version that are compatible with one another.
Create a Heroku app with this buildpack
heroku create --buildpack hashnuke/elixir
Set the buildpack for an existing Heroku app
heroku buildpacks:set hashnuke/elixir
Use the edge version of buildpack
hashnuke/elixir buildpack contains the latest published version of the buildpack, but you can use the edge version (i.e. the source code in this repo) by running:
heroku buildpacks:set https://github.com/HashNuke/heroku-buildpack-elixir.git
When you decide to use the published or the edge version of the buildpack you should be aware that, although we attempt to maintain the buildpack for as many old Elixir and Erlang releases as possible, it is sometimes difficult since there's a matrix of 3 variables involved: Erlang version, Elixir version and Heroku stack. If your application cannot be updated for some reason and requires an older version of the buildpack then use a specific version of buildpack.
Use a specific version of buildpack
The methods above always use the latest version of the buildpack code. To use a specific version of the buildpack, choose a commit from the commits page. The commit SHA forms part of your buildpack url.
For example, if you pick the commit "883f33e10879b4b8b030753c13aa3d0dda82e1e7", then the buildpack url for your app would be:
It is recommended to use a buildpack url with a commit SHA on production apps. This prevents the unpleasant moment when your Heroku build fails because the buildpack you use just got updated with a breaking change. Having buildpacks pinned to a specific version is like having your Hex packages pinned to a specific version in
Using Heroku CI
This buildpack supports Heroku CI.
- To enable viewing test runs on Heroku, add tapex to your project.
- To detect compilation warnings use the
hook_compileconfiguration option set to
mix compile --force --warnings-as-errors.
This buildpack can optionally build an Elixir release. The release build will be run after
To build and use a release for an app called
foo compiled with
- Make sure
elixir_buildpack.configis at least 1.9
web: _build/prod/rel/foo/bin/foo startin your Procfile
NOTE: This requires the master version of the buildpack (or a commit later than 7d369c)
elixir_buildpack.config file in your app's root dir. The file's syntax is bash.
If you don't specify a config option, then the default option from the buildpack's
elixir_buildpack.config file will be used.
Here's a full config file with all available options:
# Erlang version erlang_version=18.2.1 # Elixir version elixir_version=1.2.0 # Always rebuild from scratch on every deploy? always_rebuild=false # Create a release using `mix release`? (requires Elixir 1.9) release=true # A command to run right before fetching dependencies hook_pre_fetch_dependencies="pwd" # A command to run right before compiling the app (after elixir, .etc) hook_pre_compile="pwd" hook_compile="mix compile --force --warnings-as-errors" # A command to run right after compiling the app hook_post_compile="pwd" # Set the path the app is run from runtime_path=/app # Enable or disable additional test arguments test_args="--cover"
Migrating from previous build pack
the following has been deprecated and should be removed from
# Export heroku config vars config_vars_to_export=(DATABASE_URL)
Specifying Elixir version
- Use prebuilt Elixir release
- Use prebuilt Elixir branch, the branch specifier ensures that it will be downloaded every time
Specifying Erlang version
- You can specify an Erlang release version like below
Specifying config vars to export at compile time
- To set a config var on your heroku node you can exec from the shell:
heroku config:set MY_VAR=the_value
Add your own
Procfileto your application, else the default web task
mix run --no-haltwill be used.
Your application should build embedded and start permanent. Build embedded will consolidate protocols for a performance boost, start permanent will ensure that Heroku restarts your application if it crashes. See below for an example of how to use these features in your Mix project:
defmodule MyApp.Mixfile do use Mix.Project def project do [app: :my_app, version: "0.0.1", build_embedded: Mix.env == :prod, start_permanent: Mix.env == :prod] end end
The buildpack will execute the commands configured in
hook_post_compilein the root directory of your application before/after it has been compiled (respectively). These scripts can be used to build or prepare things for your application, for example compiling assets.
The buildpack will execute the commands configured in
hook_pre_fetch_dependenciesin the root directory of your application before it fetches the application dependencies. This script can be used to clean certain dependencies before fetching new ones.
- Build scripts to build erlang are at https://github.com/HashNuke/heroku-buildpack-elixir-otp-builds
- Sample app to test is available at https://github.com/HashNuke/heroku-buildpack-elixir-test
To run tests
git clone https://github.com/HashNuke/heroku-buildpack-elixir export BUILDPACK="$(pwd)/heroku-buildpack-elixir" git clone https://github.com/jesseshieh/heroku-buildpack-testrunner git clone https://github.com/jesseshieh/shunit2 export SHUNIT_HOME="$(pwd)/shunit2" cd heroku-buildpack-testrunner bin/run $BUILDPACK
© Akash Manohar under The MIT License. Feel free to do whatever you want with it.