wait until runsv is reading from supervise/ok

If the supervise/ok pipe already exists on disk before runsv has
started, then existence check here is not enough.

Since runsv opens the pipe for reading as part of its startup, we can
open it for writing which will block until runsv has called open.

A version of this fix has been running in one of our internal projects
for some time.

Signed-off-by: Steven Danna <[email protected]>

Author: stevendanna

libraries/helpers.rb

@@ -55,13 +55,21 @@ def delete_extra_env_files
     def wait_for_service
       raise 'Runit does not appear to be installed. Include runit::default before using the resource!' unless binary_exists?
 
-      sleep 1 until ::FileTest.pipe?(::File.join(service_dir_name, 'supervise', 'ok'))
+      wait_for_pipe(::File.join(service_dir_name, 'supervise', 'ok'))
 
       if new_resource.log
-        sleep 1 until ::FileTest.pipe?(::File.join(service_dir_name, 'log', 'supervise', 'ok'))
+        wait_for_pipe(::File.join(service_dir_name, 'log', 'supervise', 'ok'))
       end
     end
 
+    def wait_for_pipe(path)
+      sleep 1 until ::FileTest.pipe?(path)
+
+      # Opening the pipe for writing should block until the supervisor
+      # has opened it for reading.
+      ::File.open(path, "w").close()
+    end
+
     def runit_send_signal(signal, friendly_name = nil)
       friendly_name ||= signal
       converge_by("send #{friendly_name} to #{new_resource}") do