support systemd-style socket activation via environment

While I have my reservations about systemd, socket activation alone
is a good idea and we already have existing infrastructure for
supporting it in SIGUSR2 upgrades.

We are intentionally avoiding linkage to libsystemd to avoid dealing
with ABI compatibility issues between old and new systems.  This
also allows us to integrate more easily with non-systemd systems
which use the same environment variables as systemd.

1 files changed, 32 insertions, 0 deletions

diff --git a/test/inherit.rb b/test/inherit.rb
index b342ab0..34aa52f 100644
--- a/test/inherit.rb
+++ b/test/inherit.rb
@@ -142,4 +142,36 @@ class TestInherit < Test::Unit::TestCase
     @err.rewind
     assert_match(/failed to parse/, @err.read)
   end
+
+  def test_inherit_systemd
+    # disabled test on old Rubies: https://bugs.ruby-lang.org/issues/11336
+    # [ruby-core:69895] [Bug #11336] fixed by r51576
+    return unless RUBY_VERSION.to_f >= 2.3
+
+    mgmt = TCPServer.new(@host, 0)
+    @to_close << mgmt
+    mport = mgmt.addr[1]
+    cmd = %W(cmogstored --docroot=#@tmpdir --httplisten=#@host:#@port
+             --mgmtlisten=#@host:#{mport} --maxconns=100)
+    @pid = fork do
+      ENV['LISTEN_PID'] = "#$$"
+      ENV['LISTEN_FDS'] = '2'
+      exec(*cmd, 3 => mgmt.fileno, 4 => @srv.fileno)
+    end
+
+    # just ensure HTTP works after being inherited
+    Net::HTTP.start(@host, @port) do |http|
+      [ Net::HTTP::Get, Net::HTTP::Head ].each do |meth|
+        resp = http.request(meth.new("/"))
+        assert_kind_of Net::HTTPOK, resp
+      end
+    end
+
+    # still works since drop is open in _this_ process
+    c = TCPSocket.new(@host, mport)
+    assert_instance_of(TCPSocket, c)
+    @to_close << c
+    c.write "hello\n"
+    assert_match /ERROR: unknown command/, c.gets
+  end
 end