emulate sd_listen_fds for systemd support

systemd socket emulation shares FDs across execve, just like
the built-in SIGUSR2 upgrade process in unicorn.  Thus it is
easy to support inheriting sockets from systemd.

1 files changed, 34 insertions, 0 deletions

diff --git a/test/test_bin.rb b/test/test_bin.rb
index 8944eb3..b778a0d 100644
--- a/test/test_bin.rb
+++ b/test/test_bin.rb
@@ -11,6 +11,40 @@ class TestBin < Testcase
     @cmd = %W(ruby -I lib bin/yahns)
   end
 
+  def test_listen_fd3
+    return unless RUBY_VERSION.to_f > 2.3 # Fixed in ruby/trunk r51209, actually
+    @srv.setsockopt(:SOL_SOCKET, :SO_KEEPALIVE, 0)
+    host, port = @srv.addr[3], @srv.addr[1]
+
+    ru = tmpfile(%w(test_bin_daemon .ru))
+    ru.write("require 'rack/lobster'; run Rack::Lobster.new\n")
+    cmd = %W(ruby -I lib bin/yahns-rackup
+             -E none -p #{port} -o #{host} #{ru.path})
+    pid = fork do # emulate a systemd environment
+      env = {
+        'LISTEN_PID' => $$.to_s,
+        'LISTEN_FDS' => '1',
+      }
+      exec env, *cmd, 3 => @srv, err: @err.path
+    end
+    Net::HTTP.start(host, port) do |http|
+      req = Net::HTTP::Get.new("/")
+      res = http.request(req)
+      assert_equal 200, res.code.to_i
+      assert_equal "keep-alive", res["Connection"]
+    end
+
+    assert_equal 1, @srv.getsockopt(:SOL_SOCKET, :SO_KEEPALIVE).int,
+                 'ensure the inheriting process applies TCP socket options'
+  ensure
+    if pid
+      Process.kill(:QUIT, pid)
+      _, status = Process.waitpid2(pid)
+      assert status.success?, status.inspect
+    end
+    ru.close! if ru
+  end
+
   def test_bin_daemon_noworker_inherit
     bin_daemon(false, true)
   end