Add support for log filter default value

README.md

@@ -112,6 +112,7 @@ LOGGING = {
 +       'correlation_id': {
 +           '()': 'asgi_correlation_id.CorrelationIdFilter',
 +           'uuid_length': 32,
++           'default_value': '-',
 +       },
 +   },
     'formatters': {
@@ -341,6 +342,7 @@ def configure_logging() -> None:
                 'correlation_id': {
                     '()': 'asgi_correlation_id.CorrelationIdFilter',
                     'uuid_length': 8 if not settings.ENVIRONMENT == 'local' else 32,
+                    'default_value': '-',
                 },
             },
             'formatters': {
@@ -564,10 +566,12 @@ LOGGING = {
         'correlation_id': {
 +           '()': 'asgi_correlation_id.CorrelationIdFilter',
 +           'uuid_length': 32,
++           'default_value': '-',
 +       },
 +       'celery_tracing': {
 +            '()': 'asgi_correlation_id.CeleryTracingIdsFilter',
 +            'uuid_length': 32,
++            'default_value': '-',
 +       },
     },
     'formatters': {
@@ -646,7 +650,7 @@ your logs could look something like this:
    correlation-id               current-id
           |        parent-id        |
           |            |            |
-INFO [3b162382e1] [   None   ] [93ddf3639c] project.tasks - Debug task 1
+INFO [3b162382e1] [    -     ] [93ddf3639c] project.tasks - Debug task 1
 INFO [3b162382e1] [93ddf3639c] [24046ab022] project.tasks - Debug task 2
 INFO [3b162382e1] [93ddf3639c] [cb5595a417] project.tasks - Debug task 2
 INFO [3b162382e1] [24046ab022] [08f5428a66] project.tasks - Debug task 3

asgi_correlation_id/log_filters.py

@@ -17,9 +17,10 @@ def _trim_string(string: Optional[str], string_length: Optional[int]) -> Optiona
 class CorrelationIdFilter(Filter):
     """Logging filter to attached correlation IDs to log records"""
 
-    def __init__(self, name: str = '', uuid_length: Optional[int] = None):
+    def __init__(self, name: str = '', uuid_length: Optional[int] = None, default_value: Optional[str] = None):
         super().__init__(name=name)
         self.uuid_length = uuid_length
+        self.default_value = default_value
 
     def filter(self, record: 'LogRecord') -> bool:
         """
@@ -30,7 +31,7 @@ def filter(self, record: 'LogRecord') -> bool:
         for, if the correlation ID is added to the message, or included as
         metadata.
         """
-        cid = correlation_id.get()
+        cid = correlation_id.get(self.default_value)
         record.correlation_id = _trim_string(cid, self.uuid_length)
         return True
 
@@ -39,9 +40,10 @@ def filter(self, record: 'LogRecord') -> bool:
 
 
 class CeleryTracingIdsFilter(Filter):
-    def __init__(self, name: str = '', uuid_length: Optional[int] = None):
+    def __init__(self, name: str = '', uuid_length: Optional[int] = None, default_value: Optional[str] = None):
         super().__init__(name=name)
         self.uuid_length = uuid_length
+        self.default_value = default_value
 
     def filter(self, record: 'LogRecord') -> bool:
         """
@@ -52,8 +54,8 @@ def filter(self, record: 'LogRecord') -> bool:
         the current process. If the worker process was spawned by a beat process
         or from an endpoint, the parent ID will be None.
         """
-        pid = celery_parent_id.get()
+        pid = celery_parent_id.get(self.default_value)
         record.celery_parent_id = _trim_string(pid, self.uuid_length)
-        cid = celery_current_id.get()
+        cid = celery_current_id.get(self.default_value)
         record.celery_current_id = _trim_string(cid, self.uuid_length)
         return True

tests/test_log_filter.py

@@ -1,3 +1,4 @@
+import contextvars
 from logging import INFO, LogRecord
 from uuid import uuid4
 
@@ -6,6 +7,12 @@
 from asgi_correlation_id import CeleryTracingIdsFilter, CorrelationIdFilter
 from asgi_correlation_id.context import celery_current_id, celery_parent_id, correlation_id
 
+# Initialize context variables to obtain reset tokens which we can later use
+# when testing application of filter default values.
+correlation_id_token: contextvars.Token = correlation_id.set(None)
+celery_parent_id_token: contextvars.Token = celery_parent_id.set(None)
+celery_current_id_token: contextvars.Token = celery_current_id.set(None)
+
 
 @pytest.fixture()
 def cid():
@@ -26,6 +33,11 @@ def test_filter_has_uuid_length_attributes():
     assert filter_.uuid_length == 8
 
 
+def test_filter_has_default_value_attributes():
+    filter_ = CorrelationIdFilter(default_value='-')
+    assert filter_.default_value == '-'
+
+
 def test_filter_adds_correlation_id(cid: str, log_record: LogRecord):
     filter_ = CorrelationIdFilter()
 
@@ -43,11 +55,29 @@ def test_filter_truncates_correlation_id(cid: str, log_record: LogRecord):
     assert cid.startswith(log_record.correlation_id)  # And needs to be the first 8 characters of the id
 
 
+def test_filter_uses_default_value(cid: str, log_record: LogRecord):
+    """
+    We expect the filter to set the log record attribute to the default value
+    if the context variable is not set.
+    """
+    filter_ = CorrelationIdFilter(default_value='-')
+    correlation_id.reset(correlation_id_token)
+
+    assert not hasattr(log_record, 'correlation_id')
+    filter_.filter(log_record)
+    assert log_record.correlation_id == '-'
+
+
 def test_celery_filter_has_uuid_length_attributes():
     filter_ = CeleryTracingIdsFilter(uuid_length=8)
     assert filter_.uuid_length == 8
 
 
+def test_celery_filter_has_default_value_attributes():
+    filter_ = CeleryTracingIdsFilter(default_value='-')
+    assert filter_.default_value == '-'
+
+
 def test_celery_filter_adds_parent_id(cid: str, log_record: LogRecord):
     filter_ = CeleryTracingIdsFilter()
     celery_parent_id.set('a')
@@ -66,6 +96,22 @@ def test_celery_filter_adds_current_id(cid: str, log_record: LogRecord):
     assert log_record.celery_current_id == 'b'
 
 
+def test_celery_filter_uses_default_value(cid: str, log_record: LogRecord):
+    """
+    We expect the filter to set the log record attributes to the default value
+    if the context variables are not not set.
+    """
+    filter_ = CeleryTracingIdsFilter(default_value='-')
+    celery_parent_id.reset(celery_parent_id_token)
+    celery_current_id.reset(celery_current_id_token)
+
+    assert not hasattr(log_record, 'celery_parent_id')
+    assert not hasattr(log_record, 'celery_current_id')
+    filter_.filter(log_record)
+    assert log_record.celery_parent_id == '-'
+    assert log_record.celery_current_id == '-'
+
+
 @pytest.mark.parametrize(
     ('uuid_length', 'expected'),
     [