# Exreleasy

A minimal tool for releasing (packaging and hot updating) Elixir applications.

Standard Erlang/Elixir release tools generally attempt to generate a self contained package which contains bootup scripts, VM  arguments, shell scripts for launching nodes in the system, appup files, etc.

To the contrary, `exreleasy` tries to untie developer's hands and decouple release activities.

This tool allows to *seperately*:
* bundle an application and Erlang/Elixir with a single `mix` command and create wrapper scripts for running `mix`/`iex`;
* generate a draft for an appup file for migrating from any existing release to another one;
* perfom a hot code reload for a running node.

This is often required nowdays when we have special tools for each task, for example:
* deliver application code with Ansible(SaltStack or some other orchestration tool);
* launch nodes with Systemd generating units with an orchestration tool;
* perform maintenance tasks like running migrations or code reload with an orchestration tool.

Credit for the idea goes to [savonarola](

## Installation

  1. Add `exreleasy` to your list of dependencies in `mix.exs`:

  def deps do
    [{:exreleasy, "~> 0.4.0"}]

## Usage

### To bundle Erlang/Elixir inside your project:

    mix exreleasy.localize

This will create `./release` directory with Erlang/Elixir and wrapper scripts:


### To make a release:

    mix exreleasy.release v0.0.1

This will create `./release/archive/v0.0.1.tar.gz` archive with your project (including `./release` directory)

### To hot reload your code:

* Step 1

Generate appup file for all applications of your project.

    mix exreleasy.create_appup --old-release ./release/archive/v0.0.1.tar.gz --new-release ./release/archive/v0.0.2.tar.gz --appup ./appup_1_to_2

Alternatively use `release/exreleasy.json` from old release (fetch it from production maybe)

    mix exreleasy.create_appup --old-release /path/to/old/manifest.json --new-release ./release/archive/v0.0.2.tar.gz --appup ./appup_1_to_2

* Step 2

Edit appup file to include only modules you want to touch
Available instructions -

    vim ./appup_1_to_2

* Step 3

Apply appup file to release (creates individual appup files in ebin directories)

    mix exreleasy.apply_appup --release ./release/archive/v0.0.2.tar.gz --appup ./appup_1_to_2

Alternatively Steps 1-3 can be automated using provided script

    ./deps/exreleasy/priv/prepare_hot_release prod /path/to/old/release.tar.gz /path/to/new/release.tar.gz

* Step 4

Deploy new code to server

* Step 5

Reload code

    env MIX_ENV=prod ./release/binstubs/mix exreleasy.hot_reload --node your_node@your_host --cookie your_cookie --new-path path_to_new_code --reload-configs