Add redis SSL configuration options (#15312)

* Add SSL options to redis config

* fix lint issues

* Add documentation and changelog file

* add missing . at the end of the changelog

* Move client context factory to new file

* Rename ssl to tls and fix typo

* fix lint issues

* Added when redis attributes were added

1 files changed, 20 insertions, 7 deletions

diff --git a/synapse/replication/tcp/redis.py b/synapse/replication/tcp/redis.py

index dfc061eb5e..c8f4bf8b27 100644
--- a/synapse/replication/tcp/redis.py
+++ b/synapse/replication/tcp/redis.py
@@ -35,6 +35,7 @@ from synapse.replication.tcp.commands import (
     ReplicateCommand,
     parse_command_from_line,
 )
+from synapse.replication.tcp.context import ClientContextFactory
 from synapse.replication.tcp.protocol import (
     IReplicationConnection,
     tcp_inbound_commands_counter,
@@ -386,12 +387,24 @@ def lazyConnection(
     factory.continueTrying = reconnect
 
     reactor = hs.get_reactor()
-    reactor.connectTCP(
-        host,
-        port,
-        factory,
-        timeout=30,
-        bindAddress=None,
-    )
+
+    if hs.config.redis.redis_use_tls:
+        ssl_context_factory = ClientContextFactory(hs.config.redis)
+        reactor.connectSSL(
+            host,
+            port,
+            factory,
+            ssl_context_factory,
+            timeout=30,
+            bindAddress=None,
+        )
+    else:
+        reactor.connectTCP(
+            host,
+            port,
+            factory,
+            timeout=30,
+            bindAddress=None,
+        )
 
     return factory.handler