Phoenix: Channel Join Error when set up with docker-compose

[kkweon]

Thanks for creating Phoenix.
I have a little issue with docker-compose.
I am not really sure what is causing this, but it's reproducibile hence the issue.

Environment (Docker setup is also same as this; see below)

• Elixir version (elixir -v): Elixir 1.5.2
• Phoenix version (mix deps):

phoenix 1.3.0 (Hex package) (mix)
locked at 1.3.0 (phoenix) 1c01124c
ok

• NodeJS version (node -v): v8.7.0
• NPM version (npm -v): 5.4.2
• Operating system:

Distributor ID: Ubuntu
Description:    Ubuntu 16.04.3 LTS
Release:        16.04
Codename:       xenial

Expected behavior

1. Create a project and yes to all

mix phx.new todo

1. Change the database setting in dev.exs

config :todo, Todo.Repo,
  adapter: Ecto.Adapters.Postgres,
  username: (case System.get_env("DB_USERNAME") do
              nil -> "postgres"
              val -> val
            end),
  password: (case System.get_env("DB_PASSWORD") do
              nil -> "postgres"
              val -> val
            end),
  database: (case System.get_env("DB_NAME") do
              nil -> "todo_dev"
              val -> val
            end),
  hostname: (case System.get_env("DB_HOST") do
              nil -> "localhost"
              val -> val
            end),
  pool_size: 10

1. Create docker-compose.yml (dockerfile of the image: kkweon/phoenix)

version: "3.1"

services:
  web:
    image: kkweon/phoenix:latest
    ports:
      - "4000:4000"
    environment:
      DB_USERNAME: postgres
      DB_PASSWORD: postgres
      DB_NAME: todo_dev
      DB_HOST: db
    volumes:
      - .:/code
    depends_on:
      - db

    command: ["mix", "phx.server"]

  db:
    image: postgres:10.0
    volumes:
      - db-data:/var/lib/postgresql/data

volumes:
  db-data:

1. Set up dependencies

docker-compose run web mix deps.get
docker-compose run web mix compile
docker-compose run web mix ecto.create

and

docker-compose run web bash

# inside of container
cd assets && npm i
exit

1. Run and go to http://localhost:4000

docker-compose up

1. I expect it to run without any runtime error
   However,
   

   Actual behavior

I am getting the following error, but can't figure out what causing it since all I have done was to set up a scaffold through mix phx.new

Thank you in advance.

web_1  | [error] an exception was raised:
web_1  |     ** (RuntimeError) Channel join is expected to return one of:
web_1  | 
web_1  |     {:ok, Socket.t} |
web_1  |     {:ok, reply :: map, Socket.t} |
web_1  |     {:error, reply :: map}
web_1  | 
web_1  | got :ignore
web_1  | 
web_1  |         (phoenix) lib/phoenix/channel/server.ex:197: Phoenix.Channel.Server.init/1
web_1  |         (stdlib) gen_server.erl:365: :gen_server.init_it/2
web_1  |         (stdlib) gen_server.erl:333: :gen_server.init_it/6
web_1  |         (stdlib) proc_lib.erl:247: :proc_lib.init_p_do_apply/3

[josevalim]

@chrismccord at best we need to improve the runtime error on channel join to include the channel name. I assume this is coming from live reload but i am not sure.

[kkweon]

@josevalim Thank you! Indeed it was the live loading.
I didn't think it was relevant since the error message was saying channel.
I included inotify-tools in the docker image, and now it works without the error.

Feel free to close it though I also agree with that the channel join error message should be a little more verbose.

web_1  | [error] `inotify-tools` is needed to run `file_system` for your system, check https://github.com/rvoicilas/inotify-tools/wiki for more information about how to install it. If it's already installed but not be found, appo
int executable file with `config.exs` or `FILESYSTEM_FSINOTIFY_EXECUTABLE_FILE` env.                                                                                                                                                
web_1  | [warn] Could not start Phoenix live-reload because we cannot listen to the file system.
web_1  | You don't need to worry! This is an optional feature used during development to
web_1  | refresh your browser when you save files and it does not affect production.
web_1  | 
web_1  | [info] Running TodoWeb.Endpoint with Cowboy using http://0.0.0.0:4000
web_1  | 08:03:29 - info: compiled 6 files into 2 files, copied 3 in 509 ms
web_1  | [info] GET /
web_1  | [debug] Processing with TodoWeb.PageController.index/2
web_1  |   Parameters: %{}
web_1  |   Pipelines: [:browser]
web_1  | [info] Sent 200 in 23ms
web_1  | [error] an exception was raised:
web_1  |     ** (RuntimeError) Channel join is expected to return one of:
web_1  | 
web_1  |     {:ok, Socket.t} |
web_1  |     {:ok, reply :: map, Socket.t} |
web_1  |     {:error, reply :: map}
web_1  | 
web_1  | got :ignore
web_1  | 
web_1  |         (phoenix) lib/phoenix/channel/server.ex:197: Phoenix.Channel.Server.init/1
web_1  |         (stdlib) gen_server.erl:365: :gen_server.init_it/2
web_1  |         (stdlib) gen_server.erl:333: :gen_server.init_it/6
web_1  |         (stdlib) proc_lib.erl:247: :proc_lib.init_p_do_apply/3

Solution

If anyone finds this error, ensure that you install inotify-tools

apt-get install -y inotify-tools