Merge pull request #5732 from matrix-org/erikj/sdnotify

Add process hooks to tell systemd our state.

changelog.d/5732.feature

@@ -0,0 +1 @@
+Add sd_notify hooks to ease systemd integration and allows usage of Type=Notify.

contrib/systemd-with-workers/system/matrix-synapse-worker@.service

@@ -4,7 +4,8 @@ After=matrix-synapse.service
 BindsTo=matrix-synapse.service
 
 [Service]
-Type=simple
+Type=notify
+NotifyAccess=main
 User=matrix-synapse
 WorkingDirectory=/var/lib/matrix-synapse
 EnvironmentFile=/etc/default/matrix-synapse

contrib/systemd-with-workers/system/matrix-synapse.service

@@ -2,7 +2,8 @@
 Description=Synapse Matrix Homeserver
 
 [Service]
-Type=simple
+Type=notify
+NotifyAccess=main
 User=matrix-synapse
 WorkingDirectory=/var/lib/matrix-synapse
 EnvironmentFile=/etc/default/matrix-synapse

contrib/systemd/matrix-synapse.service

@@ -14,7 +14,9 @@
 Description=Synapse Matrix homeserver
 
 [Service]
-Type=simple
+Type=notify
+NotifyAccess=main
+ExecReload=/bin/kill -HUP $MAINPID
 Restart=on-abort
 
 User=synapse

synapse/app/_base.py

@@ -15,10 +15,12 @@
 
 import gc
 import logging
+import os
 import signal
 import sys
 import traceback
 
+import sdnotify
 from daemonize import Daemonize
 
 from twisted.internet import defer, error, reactor
@@ -242,9 +244,16 @@ def start(hs, listeners=None):
         if hasattr(signal, "SIGHUP"):
 
             def handle_sighup(*args, **kwargs):
+                # Tell systemd our state, if we're using it. This will silently fail if
+                # we're not using systemd.
+                sd_channel = sdnotify.SystemdNotifier()
+                sd_channel.notify("RELOADING=1")
+
                 for i in _sighup_callbacks:
                     i(hs)
 
+                sd_channel.notify("READY=1")
+
             signal.signal(signal.SIGHUP, handle_sighup)
 
             register_sighup(refresh_certificate)
@@ -260,6 +269,7 @@ def start(hs, listeners=None):
         hs.get_datastore().start_profiling()
 
         setup_sentry(hs)
+        setup_sdnotify(hs)
     except Exception:
         traceback.print_exc(file=sys.stderr)
         reactor = hs.get_reactor()
@@ -292,6 +302,25 @@ def setup_sentry(hs):
         scope.set_tag("worker_name", name)
 
 
+def setup_sdnotify(hs):
+    """Adds process state hooks to tell systemd what we are up to.
+    """
+
+    # Tell systemd our state, if we're using it. This will silently fail if
+    # we're not using systemd.
+    sd_channel = sdnotify.SystemdNotifier()
+
+    hs.get_reactor().addSystemEventTrigger(
+        "after",
+        "startup",
+        lambda: sd_channel.notify("READY=1\nMAINPID=%s" % (os.getpid())),
+    )
+
+    hs.get_reactor().addSystemEventTrigger(
+        "before", "shutdown", lambda: sd_channel.notify("STOPPING=1")
+    )
+
+
 def install_dns_limiter(reactor, max_dns_requests_in_flight=100):
     """Replaces the resolver with one that limits the number of in flight DNS
     requests.

synapse/app/appservice.py

@@ -168,7 +168,9 @@ def start(config_options):
     )
 
     ps.setup()
-    reactor.callWhenRunning(_base.start, ps, config.worker_listeners)
+    reactor.addSystemEventTrigger(
+        "before", "startup", _base.start, ps, config.worker_listeners
+    )
 
     _base.start_worker_reactor("synapse-appservice", config)
 

synapse/app/client_reader.py

@@ -194,7 +194,9 @@ def start(config_options):
     )
 
     ss.setup()
-    reactor.callWhenRunning(_base.start, ss, config.worker_listeners)
+    reactor.addSystemEventTrigger(
+        "before", "startup", _base.start, ss, config.worker_listeners
+    )
 
     _base.start_worker_reactor("synapse-client-reader", config)
 

synapse/app/event_creator.py

@@ -193,7 +193,9 @@ def start(config_options):
     )
 
     ss.setup()
-    reactor.callWhenRunning(_base.start, ss, config.worker_listeners)
+    reactor.addSystemEventTrigger(
+        "before", "startup", _base.start, ss, config.worker_listeners
+    )
 
     _base.start_worker_reactor("synapse-event-creator", config)
 

synapse/app/federation_reader.py

@@ -175,7 +175,9 @@ def start(config_options):
     )
 
     ss.setup()
-    reactor.callWhenRunning(_base.start, ss, config.worker_listeners)
+    reactor.addSystemEventTrigger(
+        "before", "startup", _base.start, ss, config.worker_listeners
+    )
 
     _base.start_worker_reactor("synapse-federation-reader", config)
 

synapse/app/federation_sender.py

@@ -198,7 +198,9 @@ def start(config_options):
     )
 
     ss.setup()
-    reactor.callWhenRunning(_base.start, ss, config.worker_listeners)
+    reactor.addSystemEventTrigger(
+        "before", "startup", _base.start, ss, config.worker_listeners
+    )
 
     _base.start_worker_reactor("synapse-federation-sender", config)
 

synapse/app/frontend_proxy.py

@@ -247,7 +247,9 @@ def start(config_options):
     )
 
     ss.setup()
-    reactor.callWhenRunning(_base.start, ss, config.worker_listeners)
+    reactor.addSystemEventTrigger(
+        "before", "startup", _base.start, ss, config.worker_listeners
+    )
 
     _base.start_worker_reactor("synapse-frontend-proxy", config)
 

synapse/app/homeserver.py

@@ -447,7 +447,7 @@ def setup(config_options):
                 reactor.stop()
             sys.exit(1)
 
-    reactor.callWhenRunning(start)
+    reactor.addSystemEventTrigger("before", "startup", start)
 
     return hs
 

synapse/app/media_repository.py

@@ -161,7 +161,9 @@ def start(config_options):
     )
 
     ss.setup()
-    reactor.callWhenRunning(_base.start, ss, config.worker_listeners)
+    reactor.addSystemEventTrigger(
+        "before", "startup", _base.start, ss, config.worker_listeners
+    )
 
     _base.start_worker_reactor("synapse-media-repository", config)
 

synapse/app/pusher.py

@@ -216,7 +216,7 @@ def start(config_options):
         _base.start(ps, config.worker_listeners)
         ps.get_pusherpool().start()
 
-    reactor.callWhenRunning(start)
+    reactor.addSystemEventTrigger("before", "startup", start)
 
     _base.start_worker_reactor("synapse-pusher", config)
 

synapse/app/synchrotron.py

@@ -451,7 +451,9 @@ def start(config_options):
     )
 
     ss.setup()
-    reactor.callWhenRunning(_base.start, ss, config.worker_listeners)
+    reactor.addSystemEventTrigger(
+        "before", "startup", _base.start, ss, config.worker_listeners
+    )
 
     _base.start_worker_reactor("synapse-synchrotron", config)
 

synapse/app/user_dir.py

@@ -224,7 +224,9 @@ def start(config_options):
     )
 
     ss.setup()
-    reactor.callWhenRunning(_base.start, ss, config.worker_listeners)
+    reactor.addSystemEventTrigger(
+        "before", "startup", _base.start, ss, config.worker_listeners
+    )
 
     _base.start_worker_reactor("synapse-user-dir", config)
 

synapse/python_dependencies.py

@@ -72,6 +72,7 @@ REQUIREMENTS = [
     "netaddr>=0.7.18",
     "Jinja2>=2.9",
     "bleach>=1.4.3",
+    "sdnotify>=0.3",
 ]
 
 CONDITIONAL_REQUIREMENTS = {