Split IgnorableVisit and InvalidVisitError.

We may want to reject nextVisit messages either because they specify
something we can't process (e.g., dome images for a differencing
pipeline) or because we specifically configured the service to ignore
them. The former is human error, the latter an error only in the formal
sense. Representing these cases with different exceptions lets them be
handled differently.

python/activator/activator.py

@@ -39,7 +39,8 @@
 import flask
 
 from .config import PipelinesConfig
-from .exception import GracefulShutdownInterrupt, InvalidVisitError, NonRetriableError, RetriableError
+from .exception import GracefulShutdownInterrupt, IgnorableVisit, InvalidVisitError, \
+    NonRetriableError, RetriableError
 from .logger import setup_usdf_logger
 from .middleware_interface import get_central_butler, \
     make_local_repo, make_local_cache, MiddlewareInterface
@@ -160,6 +161,7 @@ def create_app():
 
         app = flask.Flask(__name__)
         app.add_url_rule("/next-visit", view_func=next_visit_handler, methods=["POST"])
+        app.register_error_handler(IgnorableVisit, skip_visit)
         app.register_error_handler(InvalidVisitError, invalid_visit)
         app.register_error_handler(RetriableError, request_retry)
         app.register_error_handler(NonRetriableError, forbid_retry)
@@ -385,6 +387,8 @@ def process_visit(expected_visit: FannedOutVisit):
         `~activator.exception.NonRetriableError` or
         `~activator.exception.RetriableError`, depending on the program state
         at the time.
+    activator.exception.IgnorableVisit
+        Raised if the service is configured to not process ``expected_visit``.
     activator.exception.InvalidVisitError
         Raised if ``expected_visit`` is not processable.
     activator.exception.NonRetriableError
@@ -409,7 +413,7 @@ def process_visit(expected_visit: FannedOutVisit):
         assert expected_visit.instrument == instrument_name, \
             f"Expected {instrument_name}, received {expected_visit.instrument}."
         if not main_pipelines.get_pipeline_files(expected_visit):
-            raise InvalidVisitError(f"No pipeline configured for {expected_visit}.")
+            raise IgnorableVisit(f"No pipeline configured for {expected_visit}.")
 
         log_factory = logging.getLogRecordFactory()
         with log_factory.add_context(group=expected_visit.groupId,
@@ -528,6 +532,11 @@ def invalid_visit(e: InvalidVisitError) -> tuple[str, int]:
     return f"Cannot process visit: {e}.", 422
 
 
+def skip_visit(e: IgnorableVisit) -> tuple[str, int]:
+    _log.info("Skipping visit: %s", e)
+    return f"Skipping visit without processing: {e}.", 422
+
+
 def request_retry(e: RetriableError):
     error = e.nested if e.nested else e
     _log.error("Processing failed but can be retried: ", exc_info=error)

python/activator/exception.py

@@ -20,7 +20,9 @@
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 
-__all__ = ["NonRetriableError", "RetriableError", "GracefulShutdownInterrupt", "InvalidVisitError"]
+__all__ = ["NonRetriableError", "RetriableError", "GracefulShutdownInterrupt",
+           "InvalidVisitError", "IgnorableVisit",
+           ]
 
 
 class NonRetriableError(Exception):
@@ -94,3 +96,14 @@ class InvalidVisitError(ValueError):
     activator.visit.SummitVisit
     activator.visit.FannedOutVisit
     """
+
+
+class IgnorableVisit(ValueError):
+    """An exception raised if a visit object has fields that are valid,
+    but that is configured to not be processed.
+
+    See Also
+    --------
+    activator.visit.SummitVisit
+    activator.visit.FannedOutVisit
+    """