[PATCH] doc: reference --keep-file-descriptors for "bundle exec"

[Eric Wong <e@80x24.org>]

Amir Yalon <amiryal@yxejamir.net> wrote:
> It became obvious that RVM is not to blame, and the real culprit was
> Bundler’s `bundle exec` script.  From here it was just a matter of
> figuring out how to launch the unicorn script from within the bundle
> using the correct ruby without calling `bundle exec`.  There are a
> number of ways to do that, here is what worked for me:

Ahah, seems like an old problem with bundler defaults.

> ExecStart = /usr/local/rvm/gems/ruby-2.0.0-p645/wrappers/ruby -r
> bundler/setup vendor/bundle/ruby/2.0.0/bin/unicorn -c
> config/unicorn/unicorn.rb -E staging -s myapp@%i

Actually, "bundle exec --keep-file-descriptors" should work
nowadays.  See patch below.

> Thanks again to all participants, your input was invaluable.

No problem.

> P.S.  Notice how I abuse the -s no-op parameter to identify which
> template instance is running in systemd (in the output of ps, for
> example), maybe worth documenting it as a feature?

*shrug* I prefer to use full the full path to the config file
which would already include the app name in it:

	unicorn -c /path/to/my_app/unicorn.conf.rb ...

-------------------------8<-------------------------
Subject: [PATCH] doc: reference --keep-file-descriptors for "bundle exec"

"bundle exec" alone is not suitable for use with systemd-style
socket activation due to Ruby 2.0+ behavior of setting close-on-exec
for file descriptors above 2.  However, the "--keep-file-descriptors"
option was added to bundler 1.4.0 to workaround this Ruby 2.0 change
and may be used to prevent Ruby 2.0+ from closing file descriptors
on exec.

Thanks to Amir Yalon and Christos Trochalakis for bringing up
this issue on the mailing list:

http://bogomips.org/unicorn-public/1457824748.3666627.547425122.2A828B07@webmail.messagingengine.com/
---
 Sandbox                   | 6 +++---
 examples/unicorn@.service | 2 ++
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/Sandbox b/Sandbox
index 997b92f..0760065 100644
--- a/Sandbox
+++ b/Sandbox
@@ -63,9 +63,9 @@ before_exec hook as illustrated by https://gist.github.com/534668
 === Ruby 2.0.0 close-on-exec and SIGUSR2 incompatibility
 
 Ruby 2.0.0 enforces FD_CLOEXEC on file descriptors by default.  unicorn
-has been prepared for this behavior since unicorn 4.1.0, but we forgot
-to remind the Bundler developers.  This issue is being tracked here:
-https://github.com/bundler/bundler/issues/2628
+has been prepared for this behavior since unicorn 4.1.0, and bundler
+needs the "--keep-file-descriptors" option for "bundle exec":
+http://bundler.io/man/bundle-exec.1.html
 
 == Isolate
 
diff --git a/examples/unicorn@.service b/examples/unicorn@.service
index b058da5..5b16b5b 100644
--- a/examples/unicorn@.service
+++ b/examples/unicorn@.service
@@ -11,6 +11,8 @@ Wants = unicorn.socket
 After = unicorn.socket
 
 [Service]
+# bundler users must use the "--keep-file-descriptors" switch, here:
+# ExecStart = bundle exec --keep-file-descriptors /usr/bin/unicorn ...
 ExecStart = /usr/bin/unicorn -c /path/to/unicorn.conf.rb /path/to/config.ru
 Sockets = unicorn.socket
 KillSignal = SIGQUIT
-- 
EW