Support http2 keep-alive (#90)

RELEASE_NOTES.md

@@ -14,9 +14,11 @@
 
 * The `ExponentialBackoff` and `LinearBackoff` classes now require keyword arguments for their constructor. This change was made to make the classes easier to use and to avoid confusion with the order of the arguments.
 
+- HTTP2 keep-alive is now enabled by default, with an interval of 60 seconds between pings, and a 20 second timeout for responses from the service.  These values are configurable and may be updated based on specific requirements.
+
 ## New Features
 
-<!-- Here goes the main new features and examples or instructions on how to use them -->
+- Added support for HTTP2 keep-alive.
 
 ## Bug Fixes
 

src/frequenz/client/base/channel.py

@@ -5,6 +5,7 @@
 
 import dataclasses
 import pathlib
+from datetime import timedelta
 from typing import assert_never
 from urllib.parse import parse_qs, urlparse
 
@@ -41,6 +42,20 @@ class SslOptions:
     """
 
 
+@dataclasses.dataclass(frozen=True)
+class KeepAliveOptions:
+    """Options for HTTP2 keep-alive pings."""
+
+    enabled: bool = True
+    """Whether HTTP2 keep-alive should be enabled."""
+
+    interval: timedelta = timedelta(seconds=60)
+    """The interval between HTTP2 pings."""
+
+    timeout: timedelta = timedelta(seconds=20)
+    """The time to wait for a HTTP2 keep-alive response."""
+
+
 @dataclasses.dataclass(frozen=True)
 class ChannelOptions:
     """Options for a gRPC channel."""
@@ -51,6 +66,9 @@ class ChannelOptions:
     ssl: SslOptions = SslOptions()
     """SSL options for the channel."""
 
+    keep_alive: KeepAliveOptions = KeepAliveOptions()
+    """HTTP2 keep-alive options for the channel."""
+
 
 def parse_grpc_uri(
     uri: str,
@@ -120,6 +138,40 @@ def parse_grpc_uri(
         parsed_uri.netloc if parsed_uri.port else f"{parsed_uri.netloc}:{defaults.port}"
     )
 
+    keep_alive = (
+        defaults.keep_alive.enabled
+        if options.keep_alive is None
+        else options.keep_alive
+    )
+    channel_options = (
+        [
+            ("grpc.http2.max_pings_without_data", 0),
+            ("grpc.keepalive_permit_without_calls", 1),
+            (
+                "grpc.keepalive_time_ms",
+                (
+                    (
+                        defaults.keep_alive.interval
+                        if options.keep_alive_interval is None
+                        else options.keep_alive_interval
+                    ).total_seconds()
+                    * 1000
+                ),
+            ),
+            (
+                "grpc.keepalive_timeout_ms",
+                (
+                    defaults.keep_alive.timeout
+                    if options.keep_alive_timeout is None
+                    else options.keep_alive_timeout
+                ).total_seconds()
+                * 1000,
+            ),
+        ]
+        if keep_alive
+        else None
+    )
+
     ssl = defaults.ssl.enabled if options.ssl is None else options.ssl
     if ssl:
         return secure_channel(
@@ -141,8 +193,9 @@ 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:
@@ -160,6 +213,9 @@ class _QueryParams:
     ssl_root_certificates_path: pathlib.Path | None
     ssl_private_key_path: pathlib.Path | None
     ssl_certificate_chain_path: pathlib.Path | None
+    keep_alive: bool | None
+    keep_alive_interval: timedelta | None
+    keep_alive_timeout: timedelta | None
 
 
 def _parse_query_params(uri: str, query_string: str) -> _QueryParams:
@@ -200,6 +256,26 @@ def _parse_query_params(uri: str, query_string: str) -> _QueryParams:
                 f"Option(s) {', '.join(erros)} found in URI {uri!r}, but SSL is disabled",
             )
 
+    keep_alive_option = options.pop("keep_alive", None)
+    keep_alive: bool | None = None
+    if keep_alive_option is not None:
+        keep_alive = _to_bool(keep_alive_option)
+
+    keep_alive_opts = {
+        k: options.pop(k, None)
+        for k in ("keep_alive_interval_s", "keep_alive_timeout_s")
+    }
+
+    if keep_alive is False:
+        erros = []
+        for opt_name, opt in keep_alive_opts.items():
+            if opt is not None:
+                erros.append(opt_name)
+        if erros:
+            raise ValueError(
+                f"Option(s) {', '.join(erros)} found in URI {uri!r}, but keep_alive is disabled",
+            )
+
     if options:
         names = ", ".join(options)
         raise ValueError(
@@ -209,7 +285,32 @@ def _parse_query_params(uri: str, query_string: str) -> _QueryParams:
 
     return _QueryParams(
         ssl=ssl,
-        **{k: pathlib.Path(v) if v is not None else None for k, v in ssl_opts.items()},
+        ssl_root_certificates_path=(
+            pathlib.Path(ssl_opts["ssl_root_certificates_path"])
+            if ssl_opts["ssl_root_certificates_path"] is not None
+            else None
+        ),
+        ssl_private_key_path=(
+            pathlib.Path(ssl_opts["ssl_private_key_path"])
+            if ssl_opts["ssl_private_key_path"] is not None
+            else None
+        ),
+        ssl_certificate_chain_path=(
+            pathlib.Path(ssl_opts["ssl_certificate_chain_path"])
+            if ssl_opts["ssl_certificate_chain_path"] is not None
+            else None
+        ),
+        keep_alive=keep_alive,
+        keep_alive_interval=(
+            timedelta(seconds=float(keep_alive_opts["keep_alive_interval_s"]))
+            if keep_alive_opts["keep_alive_interval_s"] is not None
+            else None
+        ),
+        keep_alive_timeout=(
+            timedelta(seconds=float(keep_alive_opts["keep_alive_timeout_s"]))
+            if keep_alive_opts["keep_alive_timeout_s"] is not None
+            else None
+        ),
     )
 
 

tests/test_channel.py

@@ -5,6 +5,7 @@
 
 import dataclasses
 import pathlib
+from datetime import timedelta
 from unittest import mock
 
 import pytest
@@ -13,6 +14,7 @@
 
 from frequenz.client.base.channel import (
     ChannelOptions,
+    KeepAliveOptions,
     SslOptions,
     _to_bool,
     parse_grpc_uri,
@@ -136,6 +138,67 @@ class _ValidUrlTestCase:
                 ),
             ),
         ),
+        _ValidUrlTestCase(
+            title="Keep-alive no defaults",
+            uri="grpc://localhost:1234?keep_alive=1&keep_alive_interval_s=300"
+            + "&keep_alive_timeout_s=60",
+            expected_host="localhost",
+            expected_port=1234,
+            expected_options=ChannelOptions(
+                keep_alive=KeepAliveOptions(
+                    enabled=True,
+                    interval=timedelta(minutes=5),
+                    timeout=timedelta(minutes=1),
+                ),
+            ),
+        ),
+        _ValidUrlTestCase(
+            title="Keep-alive default timeout",
+            uri="grpc://localhost:1234?keep_alive=1&keep_alive_interval_s=300",
+            defaults=ChannelOptions(
+                keep_alive=KeepAliveOptions(
+                    enabled=True,
+                    interval=timedelta(seconds=10),
+                    timeout=timedelta(seconds=2),
+                ),
+            ),
+            expected_host="localhost",
+            expected_port=1234,
+            expected_options=ChannelOptions(
+                keep_alive=KeepAliveOptions(
+                    enabled=True,
+                    interval=timedelta(seconds=300),
+                    timeout=timedelta(seconds=2),
+                ),
+            ),
+        ),
+        _ValidUrlTestCase(
+            title="Keep-alive default interval",
+            uri="grpc://localhost:1234?keep_alive=1&keep_alive_timeout_s=60",
+            defaults=ChannelOptions(
+                keep_alive=KeepAliveOptions(
+                    enabled=True, interval=timedelta(minutes=30)
+                ),
+            ),
+            expected_host="localhost",
+            expected_port=1234,
+            expected_options=ChannelOptions(
+                keep_alive=KeepAliveOptions(
+                    enabled=True,
+                    timeout=timedelta(minutes=1),
+                    interval=timedelta(minutes=30),
+                ),
+            ),
+        ),
+        _ValidUrlTestCase(
+            title="keep-alive disabled",
+            uri="grpc://localhost:1234?keep_alive=0",
+            expected_host="localhost",
+            expected_port=1234,
+            expected_options=ChannelOptions(
+                keep_alive=KeepAliveOptions(enabled=False),
+            ),
+        ),
     ],
     ids=lambda case: case.title,
 )
@@ -198,6 +261,35 @@ def test_parse_uri_ok(  # pylint: disable=too-many-locals
 
     assert channel == expected_channel
     expected_target = f"{expected_host}:{expected_port}"
+    expected_keep_alive = (
+        expected_options.keep_alive if "keep_alive=" in uri else defaults.keep_alive
+    )
+    expected_keep_alive_interval = (
+        expected_keep_alive.interval
+        if "keep_alive_interval_s=" in uri
+        else defaults.keep_alive.interval
+    )
+    expected_keep_alive_timeout = (
+        expected_keep_alive.timeout
+        if "keep_alive_timeout_s=" in uri
+        else defaults.keep_alive.timeout
+    )
+    expected_channel_options = (
+        [
+            ("grpc.http2.max_pings_without_data", 0),
+            ("grpc.keepalive_permit_without_calls", 1),
+            (
+                "grpc.keepalive_time_ms",
+                (expected_keep_alive_interval.total_seconds() * 1000),
+            ),
+            (
+                "grpc.keepalive_timeout_ms",
+                expected_keep_alive_timeout.total_seconds() * 1000,
+            ),
+        ]
+        if expected_keep_alive.enabled
+        else None
+    )
     if expected_ssl:
         if isinstance(expected_root_certificates, pathlib.Path):
             get_contents_mock.assert_any_call(
@@ -223,10 +315,12 @@ 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"])