Added memcached_instance column to published data.

metrics/m2i/README.md

@@ -48,9 +48,12 @@ Posting metrics to influxdb
 
 ## Querying data from InfluxDB
 
-Simplest example:
+Simple example:
 
 ```sql
-SELECT value from memcached_rps;
+SELECT value from memcached_rps
+  WHERE time > now() - 10m
+    AND "memcached_instance"='localhost:11211'
+  LIMIT 25;
 ```
 

metrics/m2i/m2i.py

@@ -144,16 +144,18 @@ def extract_rps(raw_stats):
     return requests_per_second
 
 def post_to_influxdb(rps):
-    global influxdb_endpoint
+    global influxdb_endpoint, memcached_host, memcached_port
+
+    memcached_instance = "{}:{}".format(memcached_host, memcached_port)
 
     print "Posting metrics to influxdb"
     samples = []
 
     rps_sample = {
         "name": "memcached_rps",
-        "columns": [ "value" ],
+        "columns": [ "value", "memcached_instance" ],
         "points": [
-            [rps]
+            [rps, memcached_instance]
         ]
     }