diff --git a/changelog.d/7805.misc b/changelog.d/7805.misc
new file mode 100644
index 000000000000..cbae08774a6b
--- /dev/null
+++ b/changelog.d/7805.misc
@@ -0,0 +1 @@
+Add `signing_key` property to `HomeServer` to save code duplication.
diff --git a/synapse/events/builder.py b/synapse/events/builder.py
index a0c4a40c2782..92aadfe7ef55 100644
--- a/synapse/events/builder.py
+++ b/synapse/events/builder.py
@@ -162,7 +162,7 @@ class EventBuilderFactory(object):
     def __init__(self, hs):
         self.clock = hs.get_clock()
         self.hostname = hs.hostname
-        self.signing_key = hs.config.signing_key[0]
+        self.signing_key = hs.signing_key
 
         self.store = hs.get_datastore()
         self.state = hs.get_state_handler()
diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index 687cd841ac47..07d41ec03f8e 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -87,7 +87,7 @@ def __init__(self, hs):
         self.transport_layer = hs.get_federation_transport_client()
 
         self.hostname = hs.hostname
-        self.signing_key = hs.config.signing_key[0]
+        self.signing_key = hs.signing_key
 
         self._get_pdu_cache = ExpiringCache(
             cache_name="get_pdu_cache",
diff --git a/synapse/groups/attestations.py b/synapse/groups/attestations.py
index 27b0c026556c..dab13c243f78 100644
--- a/synapse/groups/attestations.py
+++ b/synapse/groups/attestations.py
@@ -70,7 +70,7 @@ def __init__(self, hs):
         self.keyring = hs.get_keyring()
         self.clock = hs.get_clock()
         self.server_name = hs.hostname
-        self.signing_key = hs.config.signing_key[0]
+        self.signing_key = hs.signing_key
 
     @defer.inlineCallbacks
     def verify_attestation(self, attestation, group_id, user_id, server_name=None):
diff --git a/synapse/groups/groups_server.py b/synapse/groups/groups_server.py
index 8db8ab1b7bd2..8cb922ddc735 100644
--- a/synapse/groups/groups_server.py
+++ b/synapse/groups/groups_server.py
@@ -41,7 +41,7 @@ def __init__(self, hs):
         self.clock = hs.get_clock()
         self.keyring = hs.get_keyring()
         self.is_mine_id = hs.is_mine_id
-        self.signing_key = hs.config.signing_key[0]
+        self.signing_key = hs.signing_key
         self.server_name = hs.hostname
         self.attestations = hs.get_groups_attestation_signing()
         self.transport_client = hs.get_federation_transport_client()
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index b5aaa244dd07..ca7da42a3fd6 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -1567,7 +1567,7 @@ async def on_invite_request(
                 room_version,
                 event.get_pdu_json(),
                 self.hs.hostname,
-                self.hs.config.signing_key[0],
+                self.hs.signing_key,
             )
         )
 
diff --git a/synapse/handlers/groups_local.py b/synapse/handlers/groups_local.py
index 7cb106e365ec..ecdb12a7bfc4 100644
--- a/synapse/handlers/groups_local.py
+++ b/synapse/handlers/groups_local.py
@@ -70,7 +70,7 @@ def __init__(self, hs):
         self.clock = hs.get_clock()
         self.keyring = hs.get_keyring()
         self.is_mine_id = hs.is_mine_id
-        self.signing_key = hs.config.signing_key[0]
+        self.signing_key = hs.signing_key
         self.server_name = hs.hostname
         self.notifier = hs.get_notifier()
         self.attestations = hs.get_groups_attestation_signing()
diff --git a/synapse/http/matrixfederationclient.py b/synapse/http/matrixfederationclient.py
index 58aed5fd96cc..148eeb19dc5d 100644
--- a/synapse/http/matrixfederationclient.py
+++ b/synapse/http/matrixfederationclient.py
@@ -176,7 +176,7 @@ class MatrixFederationHttpClient(object):
 
     def __init__(self, hs, tls_client_options_factory):
         self.hs = hs
-        self.signing_key = hs.config.signing_key[0]
+        self.signing_key = hs.signing_key
         self.server_name = hs.hostname
 
         real_reactor = hs.get_reactor()
diff --git a/synapse/server.py b/synapse/server.py
index fe94836a2c9e..6acce2e23f37 100644
--- a/synapse/server.py
+++ b/synapse/server.py
@@ -232,6 +232,8 @@ def __init__(self, hostname: str, config: HomeServerConfig, reactor=None, **kwar
 
         self._reactor = reactor
         self.hostname = hostname
+        # the key we use to sign events and requests
+        self.signing_key = config.key.signing_key[0]
         self.config = config
         self._building = {}
         self._listening_services = []
diff --git a/tests/storage/test_base.py b/tests/storage/test_base.py
index 278961c33144..b589506c6043 100644
--- a/tests/storage/test_base.py
+++ b/tests/storage/test_base.py
@@ -25,7 +25,7 @@
 from synapse.storage.engines import create_engine
 
 from tests import unittest
-from tests.utils import TestHomeServer
+from tests.utils import TestHomeServer, default_config
 
 
 class SQLBaseStoreTestCase(unittest.TestCase):
@@ -49,10 +49,7 @@ def runWithConnection(func, *args, **kwargs):
 
         self.db_pool.runWithConnection = runWithConnection
 
-        config = Mock()
-        config._disable_native_upserts = True
-        config.caches = Mock()
-        config.caches.event_cache_size = 1
+        config = default_config(name="test", parse=True)
         hs = TestHomeServer("test", config=config)
 
         sqlite_config = {"name": "sqlite3"}