fix(project): Use an annotated type for duration strings

Inspired by: #5210

This makes an annotated type for duration strings and uses a stricter regex.

snapcraft/models/project.py

@@ -50,6 +50,7 @@
     is_architecture_supported,
 )
 
+TIME_DURATION_REGEX = re.compile(r"^([0-9]+(ns|us|ms|s|m)){1,5}$")
 ProjectName = Annotated[str, StringConstraints(max_length=40)]
 
 
@@ -286,6 +287,23 @@ def _validate_mandatory_base(base: str | None, snap_type: str | None) -> None:
         )
 
 
+def _validate_duration_string(duration: str):
+    if not TIME_DURATION_REGEX.match(duration):
+        raise ValueError(f"{duration!r} is not a valid time value")
+
+    return duration
+
+
+DurationString = Annotated[
+    str,
+    pydantic.Field(
+        examples=["1", "2s", "3m", "4ms", "5us", "6m7s8ms"],
+        pattern=TIME_DURATION_REGEX
+    ),
+    pydantic.BeforeValidator(_validate_duration_string),
+]
+
+
 class Socket(models.CraftBaseModel):
     """Snapcraft app socket definition."""
 
@@ -378,11 +396,11 @@ class App(models.CraftBaseModel):
     completer: str | None = None
     stop_command: str | None = None
     post_stop_command: str | None = None
-    start_timeout: str | None = None
-    stop_timeout: str | None = None
-    watchdog_timeout: str | None = None
+    start_timeout: DurationString | None = None
+    stop_timeout: DurationString | None = None
+    watchdog_timeout: DurationString | None = None
     reload_command: str | None = None
-    restart_delay: str | None = None
+    restart_delay: DurationString | None = None
     timer: str | None = None
     daemon: Literal["simple", "forking", "oneshot", "notify", "dbus"] | None = None
     after: UniqueList[str] = pydantic.Field(default_factory=list)
@@ -450,16 +468,6 @@ def _validate_apps_section_content(cls, command: str) -> str:
 
         return command
 
-    @pydantic.field_validator(
-        "start_timeout", "stop_timeout", "watchdog_timeout", "restart_delay"
-    )
-    @classmethod
-    def _validate_time(cls, timeval):
-        if not re.match(r"^[0-9]+(ns|us|ms|s|m)*$", timeval):
-            raise ValueError(f"{timeval!r} is not a valid time value")
-
-        return timeval
-
     @pydantic.field_validator("command_chain")
     @classmethod
     def _validate_command_chain(cls, command_chains):

tests/unit/models/test_projects.py

@@ -40,6 +40,8 @@
 
 # required project data for core24 snaps
 CORE24_DATA = {"base": "core24", "grade": "devel"}
+VALID_DURATIONS = ["10ns", "10us", "10ms", "10s", "10m", "10m4s3us"]
+INVALID_DURATIONS = ["10", "10 s", "10 seconds", "1:00", "invalid"]
 
 
 @pytest.fixture
@@ -982,59 +984,44 @@ def test_app_post_stop_command(self, app_yaml_data):
         assert project.apps is not None
         assert project.apps["app1"].post_stop_command == "test-post-stop-command"
 
-    @pytest.mark.parametrize(
-        "start_timeout", ["10", "10ns", "10us", "10ms", "10s", "10m"]
-    )
+    @pytest.mark.parametrize("start_timeout", VALID_DURATIONS)
     def test_app_start_timeout_valid(self, start_timeout, app_yaml_data):
         data = app_yaml_data(start_timeout=start_timeout)
         project = Project.unmarshal(data)
         assert project.apps is not None
         assert project.apps["app1"].start_timeout == start_timeout
 
-    @pytest.mark.parametrize(
-        "start_timeout",
-        ["10 s", "10 seconds", "1:00", "invalid"],
-    )
+    @pytest.mark.parametrize("start_timeout", INVALID_DURATIONS)
     def test_app_start_timeout_invalid(self, start_timeout, app_yaml_data):
         data = app_yaml_data(start_timeout=start_timeout)
 
         error = f"'{start_timeout}' is not a valid time value"
         with pytest.raises(pydantic.ValidationError, match=error):
             Project.unmarshal(data)
 
-    @pytest.mark.parametrize(
-        "stop_timeout", ["10", "10ns", "10us", "10ms", "10s", "10m"]
-    )
+    @pytest.mark.parametrize("stop_timeout", VALID_DURATIONS)
     def test_app_stop_timeout_valid(self, stop_timeout, app_yaml_data):
         data = app_yaml_data(stop_timeout=stop_timeout)
         project = Project.unmarshal(data)
         assert project.apps is not None
         assert project.apps["app1"].stop_timeout == stop_timeout
 
-    @pytest.mark.parametrize(
-        "stop_timeout",
-        ["10 s", "10 seconds", "1:00", "invalid"],
-    )
+    @pytest.mark.parametrize("stop_timeout", INVALID_DURATIONS)
     def test_app_stop_timeout_invalid(self, stop_timeout, app_yaml_data):
         data = app_yaml_data(stop_timeout=stop_timeout)
 
         error = f"'{stop_timeout}' is not a valid time value"
         with pytest.raises(pydantic.ValidationError, match=error):
             Project.unmarshal(data)
 
-    @pytest.mark.parametrize(
-        "watchdog_timeout", ["10", "10ns", "10us", "10ms", "10s", "10m"]
-    )
+    @pytest.mark.parametrize("watchdog_timeout", VALID_DURATIONS)
     def test_app_watchdog_timeout_valid(self, watchdog_timeout, app_yaml_data):
         data = app_yaml_data(watchdog_timeout=watchdog_timeout)
         project = Project.unmarshal(data)
         assert project.apps is not None
         assert project.apps["app1"].watchdog_timeout == watchdog_timeout
 
-    @pytest.mark.parametrize(
-        "watchdog_timeout",
-        ["10 s", "10 seconds", "1:00", "invalid"],
-    )
+    @pytest.mark.parametrize("watchdog_timeout", INVALID_DURATIONS)
     def test_app_watchdog_timeout_invalid(self, watchdog_timeout, app_yaml_data):
         data = app_yaml_data(watchdog_timeout=watchdog_timeout)
 
@@ -1048,19 +1035,14 @@ def test_app_reload_command(self, app_yaml_data):
         assert project.apps is not None
         assert project.apps["app1"].reload_command == "test-reload-command"
 
-    @pytest.mark.parametrize(
-        "restart_delay", ["10", "10ns", "10us", "10ms", "10s", "10m"]
-    )
+    @pytest.mark.parametrize("restart_delay", VALID_DURATIONS)
     def test_app_restart_delay_valid(self, restart_delay, app_yaml_data):
         data = app_yaml_data(restart_delay=restart_delay)
         project = Project.unmarshal(data)
         assert project.apps is not None
         assert project.apps["app1"].restart_delay == restart_delay
 
-    @pytest.mark.parametrize(
-        "restart_delay",
-        ["10 s", "10 seconds", "1:00", "invalid"],
-    )
+    @pytest.mark.parametrize("restart_delay", INVALID_DURATIONS)
     def test_app_restart_delay_invalid(self, restart_delay, app_yaml_data):
         data = app_yaml_data(restart_delay=restart_delay)