From 8abe57ffb6ad508a154fb5341dc51fe9695041e3 Mon Sep 17 00:00:00 2001
From: Pierre-Olivier Mercier <nemunaire@nemunai.re>
Date: Tue, 22 Jan 2019 08:50:18 +0100
Subject: [PATCH] admin: new API route to display local monitoring infos

---
 admin/api/monitor.go | 98 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 admin/api/monitor.go

diff --git a/admin/api/monitor.go b/admin/api/monitor.go
new file mode 100644
index 00000000..b8af548f
--- /dev/null
+++ b/admin/api/monitor.go
@@ -0,0 +1,98 @@
+package api
+
+import (
+	"bufio"
+	"io/ioutil"
+	"os"
+	"strconv"
+	"strings"
+
+	"github.com/julienschmidt/httprouter"
+)
+
+func init() {
+	router.GET("/api/monitor", apiHandler(
+		func(httprouter.Params, []byte) (interface{}, error) {
+			return map[string]interface{}{
+				"localhost": genLocalConstants(),
+			}, nil
+		}))
+}
+
+func readLoadAvg(fd *os.File) (ret map[string]float64) {
+	if s, err := ioutil.ReadAll(fd); err == nil {
+		f := strings.Fields(strings.TrimSpace(string(s)))
+		if len(f) >= 3 {
+			ret = map[string]float64{}
+			ret["1m"], _ = strconv.ParseFloat(f[0], 64)
+			ret["5m"], _ = strconv.ParseFloat(f[1], 64)
+			ret["15m"], _ = strconv.ParseFloat(f[2], 64)
+		}
+	}
+	return
+}
+
+func readMeminfo(fd *os.File) (ret map[string]uint64) {
+	ret = map[string]uint64{}
+
+	scanner := bufio.NewScanner(fd)
+	for scanner.Scan() {
+		f := strings.Fields(strings.TrimSpace(scanner.Text()))
+		if len(f) >= 2 {
+			if v, err := strconv.ParseUint(f[1], 10, 64); err == nil {
+				ret[strings.ToLower(strings.TrimSuffix(f[0], ":"))] = v * 1024
+			}
+		}
+	}
+
+	return
+}
+
+func readCPUStats(fd *os.File) (ret map[string]map[string]uint64) {
+	ret = map[string]map[string]uint64{}
+
+	scanner := bufio.NewScanner(fd)
+	for scanner.Scan() {
+		f := strings.Fields(strings.TrimSpace(scanner.Text()))
+		if len(f[0]) >= 4 && f[0][0:3] == "cpu" && len(f) >= 8 {
+			ret[f[0]] = map[string]uint64{}
+			var total uint64 = 0
+			for i, k := range []string{"user", "nice", "system", "idle", "iowait", "irq", "softirq"} {
+				if v, err := strconv.ParseUint(f[i + 1], 10, 64); err == nil {
+					ret[f[0]][k] = v
+					total += v
+				}
+			}
+			ret[f[0]]["total"] = total
+		}
+	}
+
+	return
+}
+
+func genLocalConstants() interface{} {
+	ret := map[string]interface{}{}
+
+	fi, err := os.Open("/proc/loadavg")
+	if err != nil {
+		return err
+	}
+	defer fi.Close()
+	ret["loadavg"] = readLoadAvg(fi)
+
+	fi, err = os.Open("/proc/meminfo")
+	if err != nil {
+		return err
+	}
+	defer fi.Close()
+	ret["meminfo"] = readMeminfo(fi)
+
+	fi, err = os.Open("/proc/stat")
+	if err != nil {
+		return err
+	}
+	defer fi.Close()
+	ret["cpustat"] = readCPUStats(fi)
+
+	return ret
+}