Support http2 keep-alive

Signed-off-by: Sahas Subramanian <[email protected]>

Author: shsms

src/frequenz/client/base/channel.py

@@ -51,6 +51,16 @@ class ChannelOptions:
     ssl: SslOptions = SslOptions()
     """SSL options for the channel."""
 
+    keep_alive_time_ms: int | None = None
+    """The time in milliseconds between HTTP2 keep-alive pings.
+
+    If None, keep-alive is disabled."""
+
+    keep_alive_timeout_ms: int = 20_000
+    """The time in milliseconds to wait for a HTTP2 keep-alive response.
+
+    This is only used if `keep_alive_time_ms` is not None."""
+
 
 def parse_grpc_uri(
     uri: str,
@@ -120,6 +130,17 @@ def parse_grpc_uri(
         parsed_uri.netloc if parsed_uri.port else f"{parsed_uri.netloc}:{defaults.port}"
     )
 
+    channel_options = (
+        [
+            ("grpc.http2.max_pings_without_data", 0),
+            ("grpc.keepalive_permit_without_calls", 1),
+            ("grpc.keepalive_time_ms", defaults.keep_alive_time_ms),
+            ("grpc.keepalive_timeout_ms", defaults.keep_alive_timeout_ms),
+        ]
+        if defaults.keep_alive_time_ms is not None
+        else None
+    )
+
     ssl = defaults.ssl.enabled if options.ssl is None else options.ssl
     if ssl:
         return secure_channel(
@@ -141,8 +162,9 @@ def parse_grpc_uri(
                     defaults.ssl.certificate_chain,
                 ),
             ),
+            channel_options,
         )
-    return insecure_channel(target)
+    return insecure_channel(target, channel_options)
 
 
 def _to_bool(value: str) -> bool:

tests/test_channel.py

@@ -198,6 +198,16 @@ def test_parse_uri_ok(  # pylint: disable=too-many-locals
 
     assert channel == expected_channel
     expected_target = f"{expected_host}:{expected_port}"
+    expected_channel_options = (
+        [
+            ("grpc.http2.max_pings_without_data", 0),
+            ("grpc.keepalive_permit_without_calls", 1),
+            ("grpc.keepalive_time_ms", defaults.keep_alive_time_ms),
+            ("grpc.keepalive_timeout_ms", defaults.keep_alive_timeout_ms),
+        ]
+        if defaults.keep_alive_time_ms is not None
+        else None
+    )
     if expected_ssl:
         if isinstance(expected_root_certificates, pathlib.Path):
             get_contents_mock.assert_any_call(
@@ -223,10 +233,12 @@ def test_parse_uri_ok(  # pylint: disable=too-many-locals
             certificate_chain=expected_certificate_chain,
         )
         secure_channel_mock.assert_called_once_with(
-            expected_target, expected_credentials
+            expected_target, expected_credentials, expected_channel_options
         )
     else:
-        insecure_channel_mock.assert_called_once_with(expected_target)
+        insecure_channel_mock.assert_called_once_with(
+            expected_target, expected_channel_options
+        )
 
 
 @pytest.mark.parametrize("value", ["true", "on", "1", "TrUe", "On", "ON", "TRUE"])