From 33f2d0c18a382d7be0774e622700da36f247726a Mon Sep 17 00:00:00 2001
From: Diptanu Choudhury <diptanuc@gmail.com>
Date: Sat, 21 May 2016 20:05:51 -0700
Subject: [PATCH] Added a stats api for retreiving node stats

---
 api/allocations.go |  6 ++---
 api/nodes.go       | 57 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 60 insertions(+), 3 deletions(-)

diff --git a/api/allocations.go b/api/allocations.go
index 765a349fc..2f5415576 100644
--- a/api/allocations.go
+++ b/api/allocations.go
@@ -46,7 +46,7 @@ func (a *Allocations) Info(allocID string, q *QueryOptions) (*Allocation, *Query
 }
 
 func (a *Allocations) Stats(alloc *Allocation, q *QueryOptions) (map[string]*TaskResourceUsage, error) {
-	node, _, err := a.client.Nodes().Info(alloc.NodeID, &QueryOptions{})
+	node, _, err := a.client.Nodes().Info(alloc.NodeID, q)
 	if err != nil {
 		return nil, err
 	}
@@ -71,7 +71,7 @@ func (a *Allocations) Stats(alloc *Allocation, q *QueryOptions) (map[string]*Tas
 		return nil, err
 	}
 	if resp.StatusCode != 200 {
-		return nil, a.getErrorMsg(resp)
+		return nil, getErrorMsg(resp)
 	}
 	decoder := json.NewDecoder(resp.Body)
 	var stats map[string]*TaskResourceUsage
@@ -81,7 +81,7 @@ func (a *Allocations) Stats(alloc *Allocation, q *QueryOptions) (map[string]*Tas
 	return stats, nil
 }
 
-func (a *Allocations) getErrorMsg(resp *http.Response) error {
+func getErrorMsg(resp *http.Response) error {
 	if errMsg, err := ioutil.ReadAll(resp.Body); err == nil {
 		return fmt.Errorf(string(errMsg))
 	} else {
diff --git a/api/nodes.go b/api/nodes.go
index 7d4e6dba0..e8be07564 100644
--- a/api/nodes.go
+++ b/api/nodes.go
@@ -1,6 +1,10 @@
 package api
 
 import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
 	"sort"
 	"strconv"
 )
@@ -71,6 +75,39 @@ func (n *Nodes) ForceEvaluate(nodeID string, q *WriteOptions) (string, *WriteMet
 	return resp.EvalID, wm, nil
 }
 
+func (n *Nodes) Stats(nodeID string, q *QueryOptions) (*HostStats, error) {
+	node, _, err := n.client.Nodes().Info(nodeID, q)
+	if err != nil {
+		return nil, err
+	}
+	if node.HTTPAddr == "" {
+		return nil, fmt.Errorf("http addr of the node %q is running is not advertised", nodeID)
+	}
+	u := &url.URL{
+		Scheme: "http",
+		Host:   node.HTTPAddr,
+		Path:   "/v1/client/stats/",
+	}
+	req := &http.Request{
+		Method: "GET",
+		URL:    u,
+	}
+	c := http.Client{}
+	resp, err := c.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	if resp.StatusCode != 200 {
+		return nil, getErrorMsg(resp)
+	}
+	decoder := json.NewDecoder(resp.Body)
+	var stats *HostStats
+	if err := decoder.Decode(&stats); err != nil {
+		return nil, err
+	}
+	return stats, nil
+}
+
 // Node is used to deserialize a node entry.
 type Node struct {
 	ID                string
@@ -90,6 +127,26 @@ type Node struct {
 	ModifyIndex       uint64
 }
 
+// HostStats represents resource usage stats of the host running a Nomad client
+type HostStats struct {
+	Memory *HostMemoryStats
+	CPU    []*HostCPUStats
+}
+
+type HostMemoryStats struct {
+	Total     uint64
+	Available uint64
+	Used      uint64
+	Free      uint64
+}
+
+type HostCPUStats struct {
+	CPU    string
+	User   float64
+	System float64
+	Idle   float64
+}
+
 // NodeListStub is a subset of information returned during
 // node list operations.
 type NodeListStub struct {