Shoehorn Versions Save

• Updates
  • Improve error message when an OTP application isn't found when building the OTP release script. It's usually due to a dependency typo or wrong targets spec, so point to that.

• Updates
  • Improve detection of invalid applications being passed in the :init and :last options.
  • Fall back to a reasonable default when trying to get application modes from the release options. This fixes an exception when building the release.
  • Support release configuration via the release options in a project's mix.exs. Add a :shoehorn key to the release parameters to set :init, :last or the :exxtra_dependencies options.

This is a major update to Shoehorn that includes breaking changes:

• The :init configuration option only supports applications now. MFAs are no longer supported and moved to runtime.exs or an Application.start callback.
• References to use Shoehorn.Handler need to be updated to @behaviour Shoehorn.Handler. This may require implementing additional functions.
• Elixir 1.9 is no longer supported. Please update to Elixir 1.10 or later.

The main update to Shoehorn is to move all application startup to the boot script. This noticeably improves boot time on many Nerves platforms due to boot scripts being able to load files without traversing the entire Erlang module path list. These traversals are amazingly slow (sometimes seconds) due to a combination of SquashFS slowness in this area and slow overall IO.

Using boot scripts to load all applications has some important improvements in addition to performance:

• Application start order is deterministic and computed at compile-time. If you want to see the order, take a look at the end of the shoehorn.script in your release directory.
• Shoehorn alphabetizes the start of applications that could be ordered arbitrarily. This minimizes changes in start ordering when dependencies are added or removed.
• It enables experimental features like providing additional dependencies (using the :extra_dependencies configuration key) or hinting that dependencies get started as late as possible (the :last configuration key)
• You can remove the :app configuration key from your Shoehorn configuration. It's no longer needed.

Aside from the change from a macro to a behaviour and possibly needing to implement callback functions, Shoehorn.Handler implementations work the same as before.

Shoehorn v0.8.0 completely removes support for Distillery.

Shoehorn 0.7.0 removes support for creating boot scripts using Distillery and only supports using Elixir releases. As a result, the minimum supported version of Elixir is now version 1.9.

• Enhancements
  • Added support for Elixir 1.9+ releases.
  • Distillery is now an optional dependency and ~> 2.1.
  • Updated supervisor specs and cleaned up warnings.

• Enhancements
  • Exclude distillery, artificery, and mix from the release by default.
  • Removed RPC and application overlay modules.
  • Updated deps and docs.

• Enhancements
  • Support for distillery ~> 2.0
  • Support for Elixir ~> 1.7