Make event info plugin toggleable via env var (#264)

Closes #253

iopipe/contrib/eventinfo/plugin.py

@@ -1,13 +1,32 @@
+from distutils.util import strtobool
+import os
+
 from iopipe.plugins import Plugin
 
 from .event_types import metrics_for_event_type
 
 
 class EventInfoPlugin(Plugin):
     name = "event-info"
-    version = "1.2.0"
+    version = "1.3.0"
     homepage = "https://github.com/iopipe/iopipe-python#event-info-plugin"
-    enabled = True
+
+    def __init__(self, enabled=True):
+        """
+        Instantiates the event info plugin
+
+        :param enabled: Whether or not event info should be enabled for all
+                        invocations. Alternatively this plugin can be enabled/disabled
+                        via the `IOPIPE_EVENT_INFO_ENABLED` environment variable.
+        :type enabled: bool
+        """
+        self._enabled = enabled
+
+    @property
+    def enabled(self):
+        return self._enabled is True or bool(
+            strtobool(os.getenv("IOPIPE_EVENT_INFO_ENABLED", "false"))
+        )
 
     def pre_setup(self, iopipe):
         pass
@@ -19,7 +38,8 @@ def pre_invoke(self, event, context):
         pass
 
     def post_invoke(self, event, context):
-        metrics_for_event_type(event, context)
+        if self.enabled:
+            metrics_for_event_type(event, context)
 
     def pre_report(self, report):
         pass

tests/contrib/eventinfo/test_plugin.py

@@ -1,4 +1,7 @@
 import mock
+import os
+
+from iopipe.contrib.eventinfo import EventInfoPlugin
 
 
 @mock.patch("iopipe.report.send_report", autospec=True)
@@ -89,3 +92,11 @@ def test__eventinfo_plugin__scheduled(
     event_type = [m for m in metrics if m["name"] == "@iopipe/event-info.eventType"]
     assert len(event_type) == 1
     assert event_type[0]["s"] == "scheduled"
+
+
+def test__eventinfo_plugin__enabled(monkeypatch):
+    monkeypatch.setattr(os, "environ", {"IOPIPE_EVENT_INFO_ENABLED": "true"})
+
+    plugin = EventInfoPlugin(enabled=False)
+
+    assert plugin.enabled is True