Phoenix 1.4.0-rc.0 released!

The first release candidate of Phoenix 1.4 is out and ready for testing! Phoenix 1.4 ships with exciting new features, most notably with HTTP2 support, improved development experience with faster compile times, new error pages, and local SSL certificate generation. Additionally, our channel layer internals receiveced an overhaul, providing better structure and extensibility. We also shipped a new and improved Presence javascript API, as well as Elixir formatter integration for our

routing and test DSLs.

phx_new hex archive

The mix archive can now be installed via hex, for a simpler, versioned installation experience.

To grab the new archive, simply run:

$ mix archive.uninstall phx_new
$ mix archive.install hex phx_new 1.4.0-rc.1

The new generators also use Milligram in favor of Bootstrap to support classless markup generation. The result is nice looking defaults that allow generated markup to be much more easily customized to your individual CSS requirements.

Note: Existing Phoenix applications will continue to work on Elixir 1.4, but the new archive requires Elixir 1.5+.


Thanks to the release of Cowboy 2, Phoenix 1.4 supports H2 with a
single line change to your mix.exs. Simply add {:cowboy, "~> 2.5"}
to your deps and Phoenix will run with the Cowboy 2 adapter.

Local SSL development

Most browsers require connections over SSL for HTTP2 requests, otherwise they fallback to HTTP 1.1 requests. To aid local development

over SSL, phoenix includes a new phx.gen.cert task which generates a

self-signed certificate for HTTPS testing in development.

See the Mix.Tasks.Phx.Gen.Cert docs for more information.

Faster Development Compilation

Our development compilation speeds have improved thanks to contributions to plug and compile-time changes. You can read more about the details in my DockYard post

New Development 404 Page

Our 404 page in development now lists the available routes for the
originating router, for example:

UserSocket connection info

A highly requested feature has been access to more underlying transport information when using Phoenix channels. The 1.4 release now provides a connect/3 UserSocket callback, which can provide connection information, such as the peer IP address, host information, and X-Headers of the HTTP request for WebSocket and Long-poll transports.

Deprecated Transport macro

As part of the channel overhaul, we have deprecated the transport macro, in favor of providing transport information directly on the socket call in your endpoint. Updating is easy, by making the following changes:

# app_web/channels/user_socket.ex
- transport :websocket, Phoenix.Transports.WebSocket
- transport :longpoll, Phoenix.Transports.LongPoll, [check_origin: ...] # app_web/endpoint.ex
- socket "/socket", MyAppWeb.UserSocket
+ socket "/socket", MyAppWeb.UserSocket, + websocket: true # or list of options
+ longpoll: [check_origin: ...]

New Presence JavaScript API

A new, backwards compatible Presence JavaScript API has been introduced to both resolve race conditions as well as simplify the usage. Previously, multiple channel callbacks against

"presence_state and "presence_diff" events were required on the

client which dispatched to Presence.syncState and
Presence.syncDiff functions. Now, the interface has been unified to
a single onSync callback and the presence object tracks its own
channel callbacks and state. For example:

let presence = new Presence(roomChannel)
presence.onSync(() => { console.log("users online:", presence.list((id, {name}) => name))

That’s all there is to it!


The mix generator now uses webpack for asset generation instead of brunch. The development experience remains the same – javascript goes in assets/js , css goes in assets/css , static assets live in assets/static , so those not interested in JS tooling nuances can continue the same patterns while using webpack. Those in need of optimal js tooling can benefit from webpack’s more sophisticated code bunding, with dead code elimination and more.

Programming Phoenix Book

The Programming Phoenix Book is in beta and available through PragProg, and includes all the latest changes for 1.4. We have titled the book “>= 1.4” and consider it relatively future proof as we continue

minor version releases.

Special Thank You’s

We would like to specially thank Loïc Hoguin for his work on Cowboy 2, allowing us to provide a first-class HTTP2 experience. We would also like to thank Bram Verburg, who contributed the local SSL certificate generation,

for cross-platform, dependency-free cert generation.

As always, we have provided step-by-step instructions for bringing your 1.3.x apps up to speed:

Please report issues to the issue tracker, and find us on
#elixir-lang, elixir slack, and the Elixir forum if you have any
questions. The full list of changes from the changelog can be found below.

Happy hacking!



  • [ChannelTest] Respect user’s configured ExUnit :assert_receive_timeout for macro assertions
  • [Controller] Support partial file downloads with :offset and :length options to send_download/3
  • [Controller] Add additional security headers to put_secure_browser_headers (x-content-type-options, x-download-options, and x-permitted-cross-domain-policies)
  • [Controller] Add put_router_url/2 to override the default URL generation pulled from endpoint configuration
  • [Endpoint] Add Cowboy2Adapter for HTTP2 support with cowboy2
  • [Endpoint] The socket/3 macro now accepts direct configuration about websockets and longpoll
  • [Endpoint] Support MFA function in :check_origin config for custom origin checking
  • [Endpoint] Add new :phoenix_error_render instrumentation callback
  • [Logger] Add whitelist support to filter_parameters logger configuration, via new :keep tuple format
  • [Phoenix] Add Phoenix.json_library/0 and replace Poison with Jason for JSON encoding in new projects
  • [Router] Display list of available routes on debugger 404 error page
  • [Router] Raise on duplicate plugs in pipe_through scopes
  • [Presence] Add Presence.get_by_key to fetch presences for specific user
  • [Socket] Add new phoenix_socket_connect instrumentation
  • [Logger] Log calls to user socket connect

Bug Fixes

  • [Channel] Fix issue with WebSocket transport sending wrong ContentLength header with 403 response
  • [Router] Fix forward aliases failing to expand within scope block


  • [Controller] Passing a view in render/3 and render/4 is deprecated in favor of put_view/2
  • [Endpoint] The :handler option in the endpoint is deprecated in favor of :adapter
  • [Socket] transport/3 is deprecated. The transport is now specified in the endpoint
  • [Transport] The transport system has seen an overhaul and been drastically simplified. The previous mechanism for building transports is still supported but it is deprecated. Please see Phoenix.Socket.Transport for more information installer

  • Generate new Elixir 1.5+ child spec (therefore new apps require Elixir v1.5)
  • Use webpack for asset bundling

JavaScript client

  • Add new instance-based Presence API with simplified synchronization callbacks
  • Accept a function for socket and channel params for dynamic parameter generation when connecting and joining
  • Fix race condition when presence diff arrives before state