Add a CLI input parameter for default ttl

Signed-off-by: Bob Haddleton <bob.haddleton@nokia.com>

Author: bobh66

crossplane/function/cli.py

@@ -17,6 +17,11 @@
 Provides reusable options and a run helper so that every composition
 function shares a standard set of flags, environment variables, and defaults.
 
+Standard flags include ``--address``, ``--debug``, ``--insecure``,
+``--tls-server-certs-dir``, gRPC message size limits, and ``--ttl``. Each
+option also supports a corresponding environment variable (for example
+``ADDRESS``, ``DEBUG``, ``TTL``).
+
 Usage in a function's main.py::
 
     import click
@@ -38,20 +43,96 @@ def cli(cache_size, **kwargs):
         sdkcli.run(runner, **kwargs)
 """
 
+import datetime
 import functools
+import re
 from collections.abc import Callable
 from typing import TypeVar
 
 import click
 
-from crossplane.function import logging, runtime
+from crossplane.function import logging, response, runtime
 from crossplane.function.proto.v1 import run_function_pb2_grpc as grpcv1
 
 F = TypeVar("F", bound=Callable)
 
 DEFAULT_ADDRESS = "0.0.0.0:9443"
 DEFAULT_MAX_RECV_MESSAGE_SIZE = 4  # MB
 
+_UNIT_TO_SECONDS = {
+    "s": 1,
+    "m": 60,
+    "h": 3600,
+    "d": 86400,
+}
+_DURATION_COMPONENT_RE = re.compile(r"(\d+(?:\.\d+)?)([smhd])")
+
+
+def parse_duration(value: str) -> datetime.timedelta:
+    """Parse a duration string into a :class:`datetime.timedelta`.
+
+    Accepts Go-style duration strings (e.g. ``60s``, ``1m``, ``1h30m``) and bare
+    integers interpreted as seconds (e.g. ``60``).
+
+    Args:
+        value: The duration string to parse.
+
+    Returns:
+        The parsed duration.
+
+    Raises:
+        ValueError: If the string is empty, invalid, or negative.
+    """
+    value = value.strip()
+    if not value:
+        msg = "duration must not be empty"
+        raise ValueError(msg)
+
+    if value.isdigit():
+        return datetime.timedelta(seconds=int(value))
+
+    total_seconds = 0.0
+    pos = 0
+    for match in _DURATION_COMPONENT_RE.finditer(value):
+        if match.start() != pos:
+            msg = f"invalid duration: {value}"
+            raise ValueError(msg)
+        total_seconds += float(match.group(1)) * _UNIT_TO_SECONDS[match.group(2)]
+        pos = match.end()
+
+    if pos != len(value):
+        msg = f"invalid duration: {value}"
+        raise ValueError(msg)
+
+    if total_seconds < 0:
+        msg = "duration must not be negative"
+        raise ValueError(msg)
+
+    return datetime.timedelta(seconds=total_seconds)
+
+
+class DurationParamType(click.ParamType):
+    """A Click parameter type that parses duration strings."""
+
+    name = "duration"
+
+    def convert(
+        self,
+        value: object,
+        param: click.Parameter | None,
+        ctx: click.Context | None,
+    ) -> datetime.timedelta:
+        """Convert a CLI value to a :class:`datetime.timedelta`."""
+        if isinstance(value, datetime.timedelta):
+            return value
+        try:
+            return parse_duration(str(value))
+        except ValueError as e:
+            self.fail(str(e), param, ctx)
+
+
+DURATION = DurationParamType()
+
 
 def standard_options(func: F) -> F:
     """Apply the standard Composition Function CLI options to a Click command."""
@@ -101,6 +182,16 @@ def standard_options(func: F) -> F:
         envvar="DEBUG",
         help="Emit debug logs.",
     )
+    @click.option(
+        "--ttl",
+        type=DURATION,
+        default=None,
+        show_default="1m",
+        envvar="TTL",
+        help="Default TTL for RunFunctionResponses. "
+        "Controls how long Crossplane may cache the response "
+        "before re-invoking the function.",
+    )
     @functools.wraps(func)
     def wrapper(*args, **kwargs):
         return func(*args, **kwargs)
@@ -117,11 +208,15 @@ def run(  # noqa: PLR0913
     insecure: bool,
     max_recv_message_size: int,
     max_send_message_size: int | None,
+    ttl: datetime.timedelta | None,
 ) -> None:
     """Start a composition function gRPC server with standard options."""
     level = logging.Level.DEBUG if debug else logging.Level.INFO
     logging.configure(level=level)
 
+    if ttl is not None:
+        response.set_default_ttl(ttl)
+
     if max_send_message_size is None:
         max_send_message_size = max_recv_message_size
 

crossplane/function/response.py

@@ -25,23 +25,45 @@
 """The default TTL for which a RunFunctionResponse may be cached."""
 DEFAULT_TTL = datetime.timedelta(minutes=1)
 
+_default_ttl = DEFAULT_TTL
+
+
+def get_default_ttl() -> datetime.timedelta:
+    """Return the process-wide default TTL for RunFunctionResponses."""
+    return _default_ttl
+
+
+def set_default_ttl(ttl: datetime.timedelta) -> None:
+    """Set the process-wide default TTL for RunFunctionResponses.
+
+    Args:
+        ttl: How long Crossplane may optionally cache responses when no explicit
+            TTL is passed to :func:`to`.
+    """
+    global _default_ttl  # noqa: PLW0603
+    _default_ttl = ttl
+
 
 def to(
     req: fnv1.RunFunctionRequest,
-    ttl: datetime.timedelta = DEFAULT_TTL,
+    ttl: datetime.timedelta | None = None,
 ) -> fnv1.RunFunctionResponse:
     """Create a response to the supplied request.
 
     Args:
         req: The request to respond to.
-        ttl: How long Crossplane may optionally cache the response.
+        ttl: How long Crossplane may optionally cache the response. Defaults to
+            the process-wide default TTL set by :func:`set_default_ttl`.
 
     Returns:
         A response to the supplied request.
 
     The request's tag, desired resources, and context is automatically copied to
     the response. Using response.to is a good pattern to ensure
     """
+    if ttl is None:
+        ttl = get_default_ttl()
+
     dttl = durationpb.Duration()
     dttl.FromTimedelta(ttl)
     return fnv1.RunFunctionResponse(

tests/test_cli.py

@@ -0,0 +1,191 @@
+# Copyright 2026 The Crossplane Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import dataclasses
+import datetime
+import unittest
+from unittest import mock
+
+import click
+from click.testing import CliRunner
+from google.protobuf import duration_pb2 as durationpb
+from google.protobuf import json_format
+
+from crossplane.function import cli, response
+from crossplane.function.proto.v1 import run_function_pb2 as fnv1
+
+
+class TestParseDuration(unittest.TestCase):
+    def test_parse_duration(self) -> None:
+        @dataclasses.dataclass
+        class TestCase:
+            reason: str
+            value: str
+            want: datetime.timedelta
+
+        cases = [
+            TestCase(
+                reason="Bare integers are interpreted as seconds.",
+                value="60",
+                want=datetime.timedelta(seconds=60),
+            ),
+            TestCase(
+                reason="Seconds suffix should work.",
+                value="60s",
+                want=datetime.timedelta(seconds=60),
+            ),
+            TestCase(
+                reason="Minutes suffix should work.",
+                value="1m",
+                want=datetime.timedelta(minutes=1),
+            ),
+            TestCase(
+                reason="Hours suffix should work.",
+                value="1h",
+                want=datetime.timedelta(hours=1),
+            ),
+            TestCase(
+                reason="Days suffix should work.",
+                value="1d",
+                want=datetime.timedelta(days=1),
+            ),
+            TestCase(
+                reason="Combined durations should be summed.",
+                value="1h30m",
+                want=datetime.timedelta(hours=1, minutes=30),
+            ),
+            TestCase(
+                reason="Zero seconds should work.",
+                value="0s",
+                want=datetime.timedelta(seconds=0),
+            ),
+            TestCase(
+                reason="Zero as a bare integer should work.",
+                value="0",
+                want=datetime.timedelta(seconds=0),
+            ),
+            TestCase(
+                reason="Fractional seconds should work.",
+                value="1.5s",
+                want=datetime.timedelta(seconds=1.5),
+            ),
+        ]
+
+        for case in cases:
+            got = cli.parse_duration(case.value)
+            self.assertEqual(case.want, got, case.reason)
+
+    def test_parse_duration_invalid(self) -> None:
+        for value in ("", "1x", "-5m", "1m2"):
+            with self.assertRaises(ValueError, msg=value):
+                cli.parse_duration(value)
+
+
+class TestStandardOptions(unittest.TestCase):
+    def setUp(self) -> None:
+        self._saved_default_ttl = response.get_default_ttl()
+
+    def tearDown(self) -> None:
+        response.set_default_ttl(self._saved_default_ttl)
+
+    def test_run_sets_default_ttl_from_flag(self) -> None:
+        @click.command()
+        @cli.standard_options
+        def main(**kwargs):
+            cli.run(mock.Mock(), **kwargs)
+
+        runner = CliRunner()
+        with mock.patch("crossplane.function.cli.runtime.serve"):
+            result = runner.invoke(main, ["--ttl", "5m", "--insecure"])
+        self.assertEqual(0, result.exit_code, result.output)
+        self.assertEqual(datetime.timedelta(minutes=5), response.get_default_ttl())
+
+    def test_run_sets_default_ttl_from_env(self) -> None:
+        @click.command()
+        @cli.standard_options
+        def main(**kwargs):
+            cli.run(mock.Mock(), **kwargs)
+
+        runner = CliRunner()
+        with mock.patch("crossplane.function.cli.runtime.serve"):
+            result = runner.invoke(
+                main,
+                ["--insecure"],
+                env={"TTL": "10m"},
+            )
+        self.assertEqual(0, result.exit_code, result.output)
+        self.assertEqual(datetime.timedelta(minutes=10), response.get_default_ttl())
+
+    def test_run_leaves_default_ttl_when_flag_omitted(self) -> None:
+        response.set_default_ttl(response.DEFAULT_TTL)
+
+        @click.command()
+        @cli.standard_options
+        def main(**kwargs):
+            cli.run(mock.Mock(), **kwargs)
+
+        runner = CliRunner()
+        with mock.patch("crossplane.function.cli.runtime.serve"):
+            result = runner.invoke(main, ["--insecure"])
+        self.assertEqual(0, result.exit_code, result.output)
+        self.assertEqual(response.DEFAULT_TTL, response.get_default_ttl())
+
+    def test_invalid_ttl_flag(self) -> None:
+        @click.command()
+        @cli.standard_options
+        def main(**kwargs):
+            cli.run(mock.Mock(), **kwargs)
+
+        runner = CliRunner()
+        result = runner.invoke(main, ["--ttl", "1x", "--insecure"])
+        self.assertNotEqual(0, result.exit_code)
+
+    def test_ttl_flag_affects_response_to(self) -> None:
+        @click.command()
+        @cli.standard_options
+        def main(**kwargs):
+            cli.run(mock.Mock(), **kwargs)
+
+        runner = CliRunner()
+        with mock.patch("crossplane.function.cli.runtime.serve"):
+            result = runner.invoke(main, ["--ttl", "5m", "--insecure"])
+        self.assertEqual(0, result.exit_code, result.output)
+
+        req = fnv1.RunFunctionRequest(meta=fnv1.RequestMeta(tag="hi"))
+        got = response.to(req)
+        want = fnv1.RunFunctionResponse(
+            meta=fnv1.ResponseMeta(tag="hi", ttl=durationpb.Duration(seconds=60 * 5)),
+            desired=req.desired,
+            context=req.context,
+        )
+        self.assertEqual(
+            json_format.MessageToJson(want, sort_keys=True),
+            json_format.MessageToJson(got, sort_keys=True),
+        )
+
+
+class TestDurationParamType(unittest.TestCase):
+    def test_convert(self) -> None:
+        param_type = cli.DurationParamType()
+        got = param_type.convert("5m", None, None)
+        self.assertEqual(datetime.timedelta(minutes=5), got)
+
+    def test_convert_invalid(self) -> None:
+        param_type = cli.DurationParamType()
+        with self.assertRaises(click.BadParameter):
+            param_type.convert("1x", None, None)
+
+
+if __name__ == "__main__":
+    unittest.main()