Set correct host name in metrics

This commit fixes a bug where hostnames were not correct in
metrics collected by Snap and Hindsight. It relies on
Kubernetes' downward API and the spec.nodeName field [1].
The latter is only supported by Kubernetes 1.4 and higher,
and the deployment of stacklight-collector pods will fail if
Kubernetes 1.3 or lower is used.

[1] <https://github.com/kubernetes/kubernetes/pull/27880>

Change-Id: I73cd35803a2201a09144bf925753156e47489cff
Depends-On: I293bb3aa113883c02f2e738f9d74291bf2f23d95
Partial-Bug: #1614484

docker/hindsight/output/influxdb_tcp.lua

@@ -105,10 +105,7 @@ end
 -- if the message is invalid
 local function create_line()
 
-    -- FIXME(elemoine) get hostname from Field[Hostname]
-    local tags = {
-        hostname = escape_string(read_message('Hostname'))
-    }
+    local tags = {}
     local dimensions, dimensions_index = read_field('dimensions')
     if dimensions then
         local i = 0

service/files/hindsight.cfg.j2

@@ -6,8 +6,7 @@ analysis_lua_cpath      = "/usr/lib/x86_64-linux-gnu/luasandbox/modules/?.so"
 io_lua_path             = analysis_lua_path .. ";/usr/lib/x86_64-linux-gnu/luasandbox/io_modules/?.lua"
 io_lua_cpath            = analysis_lua_cpath .. ";/usr/lib/x86_64-linux-gnu/luasandbox/io_modules/?.so"
 
--- FIXME(elemoine) set "hostname"
--- hostname =
+hostname = "{{ CCP_HINDSIGHT_NODE_NAME }}"
 
 input_defaults = {
   -- output_limit      = 64 * 1024

service/files/snap-task.json.j2

@@ -12,6 +12,11 @@
               "proc_path":  "/host-proc"
           }
       },
+      "tags": {
+          "/intel/procfs": {
+              "hostname": "{{ CCP_SNAP_NODE_NAME }}"
+          }
+      },
       "metrics": {
         "/intel/procfs/cpu/all/idle_percentage": {},
         "/intel/procfs/cpu/all/iowait_percentage": {},

service/stacklight-collector.yaml

@@ -40,10 +40,15 @@ service:
           type: host
           path: /proc
           mount-path: /host-proc
+      env:
+        - name: CCP_SNAP_NODE_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: spec.nodeName
 files:
   hindsight.cfg:
     path: /etc/hindsight/hindsight.cfg
-    content: hindsight.cfg
+    content: hindsight.cfg.j2
     perm: "0600"
   heka-tcp.cfg:
     path: /var/lib/hindsight/run/input/heka_tcp.cfg