Implement include/exclude rules. Set MAX_CONTAINERS_WITHOUT_RULES to …

…limit

the number of collected containers if no rules are supplied.

checks.d/docker.py

@@ -3,10 +3,12 @@
 import httplib
 import socket
 import os
+import re
 from urlparse import urlsplit, urljoin
 from util import json, headers
 from checks import AgentCheck
 
+MAX_CONTAINERS_WITHOUT_RULES = 10
 
 LXC_METRICS = [
     {
@@ -119,13 +121,23 @@ def check(self, instance):
         containers = self._get_containers(instance)
         if not containers:
             self.warning("No containers are running.")
+
+        # If we don't have include/exclude rules, we cap to
+        # MAX_CONTAINERS_WITHOUT_RULES containers to collect.
+        if not instance.get("exclude") or not instance.get("include"):
+            containers = containers[:MAX_CONTAINERS_WITHOUT_RULES]
         for container in containers:
             container_details = self._get_container(instance, container["Id"])
             container_tags = list(tags)
             for key in DOCKER_TAGS:
-                container_tags.append("%s:%s" % (key.lower(), container_details[key]))
+                container_tags.append(self._make_tag(key, container_details[key]))
             for key in DOCKER_CONFIG_TAGS:
-                container_tags.append("%s:%s" % (key.lower(), container_details["Config"][key]))
+                container_tags.append(self._make_tag(key, container_details["Config"][key]))
+
+            # Check if the container is included/excluded via its tags
+            if not self._is_container_included(instance, container_tags):
+                continue
+
             for key, (dd_key, metric_type) in DOCKER_METRICS.items():
                 if key in container:
                     getattr(self, metric_type)(dd_key, int(container[key]), tags=container_tags)
@@ -137,6 +149,23 @@ def check(self, instance):
                     if key in stats:
                         getattr(self, metric_type)(dd_key, int(stats[key]), tags=container_tags)
 
+    def _make_tag(self, key, value):
+        return "%s:%s" % (key.lower(), value)
+
+    def _is_container_included(self, instance, tags):
+        def _is_tag_included(tag):
+            for exclude_rule in instance.get("exclude") or []:
+                if re.match(exclude_rule, tag):
+                    for include_rule in instance.get("include") or []:
+                        if re.match(include_rule, tag):
+                            return True
+                    return False
+            return True
+        for tag in tags:
+            if _is_tag_included(tag):
+                return True
+        return False
+
     def _get_containers(self, instance):
         """Gets the list of running containers in Docker."""
         return self._get_json("%(url)s/containers/json" % instance, params={"size": 1})

conf.d/docker.yaml.example

@@ -2,3 +2,27 @@ init_config:
 
 instances:
     - url: "unix://var/run/docker.sock"
+
+# Include/Exclude rules
+#
+# To include or exclude containers based on their tags, use the include and
+# exclude keys in your instance.
+# The reasoning is: if a tag matches an exclude rule, it won't be included
+# unless it also matches an include rule.
+#
+# Examples:
+# exclude all, except ubuntu and debian:
+# instances:
+#     - url: "unix://var/run/docker.sock"
+#       include:
+#         - "image:ubuntu"
+#         - "image:debian"
+#       exclude:
+#         - ".*"
+#
+# include all, except ubuntu and debian:
+# instances:
+#     - url: "unix://var/run/docker.sock"
+#       exclude:
+#         - "image:ubuntu"
+#         - "image:debian"