Watch for 'modify' event to enable live reload under Docker for Mac

[nicbet]

When running Phoenix framework inside Docker on a Mac OS X host, live reload functionality does not work. Similar issues have been reported with WebPack/React (https://forums.docker.com/t/docker-for-mac-inotify-events-only-working-from-vim/18772/9)

According to https://github.com/docker/for-mac/issues/896 and https://github.com/docker/for-mac/issues/681#issuecomment-248409203 it appears that Docker for Mac does not currently translate modification FSEvents to WRITE inotify events.

Modifying https://github.com/synrc/fs/blob/master/src/sys/inotifywait.erl#L11 and adding the modify event to the list of watched events fixes this issue and enables proper functioning of live reload on file edits with Elixir/Phoenix applications executing in Docker on Mac.

start_port(Path, Cwd) ->
    Path1 = filename:absname(Path),
    Args = ["-c", "inotifywait $0 $@ & PID=$!; read a; kill $PID",
            "-m", "-e", "modify", "-e", "close_write", "-e", "moved_to", "-e", "create", "-r", Path1],
    erlang:open_port({spawn_executable, os:find_executable("sh")},
        [stream, exit_status, {line, 16384}, {args, Args}, {cd, Cwd}]).

Tested on:

• Docker for Mac Version 1.13.1-beta42 (15350) Channel: beta 2ffb2b4915,
• Erlang/OTP 19 [erts-8.2.1] [source] [64-bit] [smp:2:2] [ds:2:2:10] [async-threads:10] [hipe] [kernel-poll:false],
• Elixir 1.4.1,
• Alpine Linux 1ed00bb3285b 4.9.8-moby #1 SMP Wed Feb 8 09:59:13 UTC 2017 x86_64 GNU/Linux - - Docker Base ImageFROM Elixir:1.4.1

[5HT]

start_port(Path, Cwd) ->
    Path1 = filename:absname(Path),
    Args = ["-c", "inotifywait $0 $@ & PID=$!; read a; kill $PID",
            "-m", "-e", "modify", "-e", "close_write", "-e", "moved_to",
                   "-e", "create", "-e", "delete", 
                   "-e", "attrib", "--quiet", "-r", Path1],
    erlang:open_port({spawn_executable, os:find_executable("sh")},
        [stream, exit_status, {line, 16384}, {args, Args}, {cd, Cwd}]).

I added modify flag, please check

[nicbet]

Yes with the modify flag, live reload does work (I had modified deps/fs/src/sys/inotifywait.erl on my machine before posting the issue).

Looking at the output of inotifywait -m:

• with Atom, SublimeText, TextWrangler, etc. the following notify events get propagated into the Docker container:

web/templates/page/index.html.eex ATTRIB 
web/templates/page/index.html.eex MODIFY 
web/templates/page/index.html.eex OPEN 
web/templates/page/index.html.eex ACCESS 
web/templates/page/index.html.eex CLOSE_NOWRITE,CLOSE 

• with VIM the following events get propagated

web/templates/page/index.html.eex ATTRIB 
web/templates/page/index.html.eex MODIFY 
web/templates/page/index.html.eex MODIFY 
web/templates/page/index.html.eex ATTRIB 
web/templates/page/index.html.eex MODIFY 
web/templates/page/index.html.eex MODIFY 
web/templates/page/index.html.eex OPEN 
web/templates/page/index.html.eex ACCESS 
web/templates/page/index.html.eex CLOSE_NOWRITE,CLOSE

[5HT]

But you removed for some reason the ATTRIB and DELETE in your snippet

[nicbet]

My apologies the snippet is based on 0.9.2 which is installed as a dep as part of the latest phoenix release.

[5HT]

Ah ok, so you ask me to draft a new release?

[5HT]

Ok, I added modified event in Linux backed.

[nicbet]

@5HT, it appears that fs ~> 2.12 does correctly enable live reload on Docker for Mac containers (via listening to ATTRIB) without the need to add MODIFY.

Looks like upstream phoenix_livereload has recently rolled back to fs 0.9.1 due to rebar issues, which as a side-effect ended up causing the live reload regression I'm seeing. https://github.com/phoenixframework/phoenix_live_reload/commit/e54bf6fb301436797ff589e0b76a047bb79b6870

Since fs 2.12.x fixes the live reload issue with Docker containers on Docker for Mac that is present in 0.9.2, I think the best course of action is to close this issue and wait for upstream phoenix_livereload to move back to 2.12.x.

[5HT]

Ok, let me know if there is any problem 👍