introduce basic fact collection

client/vendor/github.com/zcalusic/sysinfo/node.go

@@ -0,0 +1,99 @@
+// Copyright © 2016 Zlatko Čalušić
+//
+// Use of this source code is governed by an MIT-style license that can be found in the LICENSE file.
+
+package sysinfo
+
+import (
+	"bufio"
+	"os"
+	"strings"
+)
+
+// Node information.
+type Node struct {
+	Hostname   string `json:"hostname,omitempty"`
+	MachineID  string `json:"machineid,omitempty"`
+	Hypervisor string `json:"hypervisor,omitempty"`
+	Timezone   string `json:"timezone,omitempty"`
+}
+
+func (si *SysInfo) getHostname() {
+	si.Node.Hostname = slurpFile("/proc/sys/kernel/hostname")
+}
+
+func (si *SysInfo) getSetMachineID() {
+	const pathSystemdMachineID = "/etc/machine-id"
+	const pathDbusMachineID = "/var/lib/dbus/machine-id"
+
+	systemdMachineID := slurpFile(pathSystemdMachineID)
+	dbusMachineID := slurpFile(pathDbusMachineID)
+
+	if systemdMachineID != "" && dbusMachineID != "" {
+		// All OK, just return the machine id.
+		if systemdMachineID == dbusMachineID {
+			si.Node.MachineID = systemdMachineID
+			return
+		}
+
+		// They both exist, but they don't match! Copy systemd machine id to DBUS machine id.
+		spewFile(pathDbusMachineID, systemdMachineID, 0444)
+		si.Node.MachineID = systemdMachineID
+		return
+	}
+
+	// Copy DBUS machine id to non-existent systemd machine id.
+	if systemdMachineID == "" && dbusMachineID != "" {
+		spewFile(pathSystemdMachineID, dbusMachineID, 0444)
+		si.Node.MachineID = dbusMachineID
+		return
+	}
+
+	// Copy systemd machine id to non-existent DBUS machine id.
+	if systemdMachineID != "" && dbusMachineID == "" {
+		spewFile(pathDbusMachineID, systemdMachineID, 0444)
+		si.Node.MachineID = systemdMachineID
+		return
+	}
+}
+
+func (si *SysInfo) getTimezone() {
+	const zoneInfoPrefix = "/usr/share/zoneinfo/"
+
+	if fi, err := os.Lstat("/etc/localtime"); err == nil {
+		if fi.Mode()&os.ModeSymlink == os.ModeSymlink {
+			if tzfile, err := os.Readlink("/etc/localtime"); err == nil {
+				tzfile = strings.TrimPrefix(tzfile, "..")
+				if strings.HasPrefix(tzfile, zoneInfoPrefix) {
+					si.Node.Timezone = strings.TrimPrefix(tzfile, zoneInfoPrefix)
+					return
+				}
+			}
+		}
+	}
+
+	if timezone := slurpFile("/etc/timezone"); timezone != "" {
+		si.Node.Timezone = timezone
+		return
+	}
+
+	if f, err := os.Open("/etc/sysconfig/clock"); err == nil {
+		defer f.Close()
+		s := bufio.NewScanner(f)
+		for s.Scan() {
+			if sl := strings.Split(s.Text(), "="); len(sl) == 2 {
+				if sl[0] == "ZONE" {
+					si.Node.Timezone = strings.Trim(sl[1], `"`)
+					return
+				}
+			}
+		}
+	}
+}
+
+func (si *SysInfo) getNodeInfo() {
+	si.getHostname()
+	si.getSetMachineID()
+	si.getHypervisor()
+	si.getTimezone()
+}