Fix http_check instance tag normalization to preserve minuses

http_check/changelog.d/21381.fixed

@@ -0,0 +1 @@
+Fix instance tag normalization to preserve minuses (-) in tag values according to Datadog tag rules

http_check/datadog_checks/http_check/http_check.py

@@ -69,6 +69,31 @@ def __init__(self, name, init_config, instances):
         if is_affirmative(self.instance.get('use_cert_from_response', False)):
             self.HTTP_CONFIG_REMAPPER['disable_ssl_validation']['default'] = False
 
+    def normalize_instance_tag(self, tag):
+        # type: (Union[str, bytes]) -> str
+        """Normalize instance tag values according to Datadog tag rules.
+
+        Datadog tags may contain alphanumerics, underscores, minuses, colons, periods, and slashes.
+        Other characters are converted to underscores.
+
+        This is different from the base normalize_tag which incorrectly converts minuses to underscores.
+        """
+        if isinstance(tag, str):
+            tag = tag.encode('utf-8', 'ignore')
+
+        # Only replace characters that are NOT allowed in Datadog tags
+        # Allowed: alphanumerics, underscores, minuses, colons, periods, slashes
+        # Pattern matches: commas, pluses, asterisks, parentheses, brackets, braces, whitespaces
+        tag = re.sub(rb'[,\+\*()\[\]{}\s]', rb'_', tag)
+
+        # Clean up multiple underscores
+        tag = re.sub(rb'__+', rb'_', tag)
+
+        # Clean up underscores around dots
+        tag = re.sub(rb'_*\._*', rb'.', tag).strip(b'_')
+
+        return tag.decode('utf-8')
+
     def check(self, instance):
         (
             addr,
@@ -106,7 +131,7 @@ def send_status_down(loginfo, down_msg):
         # Store tags in a temporary list so that we don't modify the global tags data structure
         tags_list = list(tags)
         tags_list.append("url:{}".format(addr))
-        instance_name = self.normalize_tag(instance["name"])
+        instance_name = self.normalize_instance_tag(instance["name"])
         tags_list.append("instance:{}".format(instance_name))
         service_checks = []
         service_checks_tags = self._get_service_checks_tags(instance)
@@ -284,7 +309,7 @@ def send_status_down(loginfo, down_msg):
             self.report_as_service_check(sc_name, status, service_checks_tags, msg)
 
     def _get_service_checks_tags(self, instance):
-        instance_name = self.normalize_tag(instance["name"])
+        instance_name = self.normalize_instance_tag(instance["name"])
         url = instance.get("url", None)
         if url is not None:
             url = ensure_unicode(url)

http_check/tests/test_http_integration.py

@@ -404,7 +404,8 @@ def test_service_check_instance_name_normalization(aggregator, http_check):
     http_check.check(CONFIG_UNORMALIZED_INSTANCE_NAME['instances'][0])
 
     # Assess instance name normalization
-    normalized_tags = ['url:https://valid.mock', 'instance:need_to_be_normalized']
+    # With the fix, minuses are preserved: "_need-to__be_normalized-" -> "need-to_be_normalized-"
+    normalized_tags = ['url:https://valid.mock', 'instance:need-to_be_normalized-']
     aggregator.assert_service_check(HTTPCheck.SC_STATUS, status=HTTPCheck.OK, tags=normalized_tags, count=1)
     aggregator.assert_service_check(HTTPCheck.SC_SSL_CERT, status=HTTPCheck.OK, tags=normalized_tags, count=1)