Add Prometheus Node Exporter as a system install

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

Author: alexellis

README.md

@@ -251,6 +251,7 @@ Run the following to see what's available `arkade system install`:
   gitlab-runner   Install GitLab Runner
   go              Install Go
   node            Install Node.js
+  node_exporter   Install Node Exporter
   prometheus      Install Prometheus
   pwsh            Install Powershell
   registry        Install registry

cmd/system/install.go

@@ -37,5 +37,7 @@ func MakeInstall() *cobra.Command {
 	command.AddCommand(MakeInstallPowershell())
 	command.AddCommand(MakeInstallCaddyServer())
 
+	command.AddCommand(MakeInstallNodeExporter())
+
 	return command
 }

cmd/system/nodeexporter.go

@@ -0,0 +1,131 @@
+// Copyright (c) arkade author(s) 2024. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+package system
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/alexellis/arkade/pkg/env"
+	"github.com/alexellis/arkade/pkg/get"
+	"github.com/spf13/cobra"
+)
+
+func MakeInstallNodeExporter() *cobra.Command {
+	command := &cobra.Command{
+		Use:   "node_exporter",
+		Short: "Install Node Exporter",
+		Long: `Install Node Exporter which is a Prometheus exporter for hardware and OS 
+metrics exposed by a server/container such as CPU/RAM/Disk/Network.`,
+		RunE:         installNodeExporterE,
+		SilenceUsage: true,
+	}
+
+	command.Flags().StringP("version", "v", "", "The version for Go, or leave blank for pinned version")
+	command.Flags().String("path", "/usr/local/", "Installation path, where a go subfolder will be created")
+	command.Flags().Bool("progress", true, "Show download progress")
+	command.Flags().Bool("systemd", false, "Install and start a systemd service")
+
+	return command
+}
+
+func installNodeExporterE(cmd *cobra.Command, args []string) error {
+	installPath, _ := cmd.Flags().GetString("path")
+	version, _ := cmd.Flags().GetString("version")
+	progress, _ := cmd.Flags().GetBool("progress")
+	systemd, _ := cmd.Flags().GetBool("systemd")
+
+	arch, osVer := env.GetClientArch()
+
+	if cmd.Flags().Changed("os") {
+		osVer, _ = cmd.Flags().GetString("os")
+	}
+	if cmd.Flags().Changed("arch") {
+		arch, _ = cmd.Flags().GetString("arch")
+	}
+
+	if strings.ToLower(osVer) != "linux" && strings.ToLower(osVer) != "darwin" {
+		return fmt.Errorf("this app only supports Linux and Darwin")
+	}
+
+	tools := get.MakeTools()
+	var tool *get.Tool
+	for _, t := range tools {
+		if t.Name == "node_exporter" {
+			tool = &t
+			break
+		}
+	}
+
+	if tool == nil {
+		return fmt.Errorf("unable to find node_exporter definition")
+	}
+
+	fmt.Printf("Installing node_exporter Server to %s\n", installPath)
+
+	installPath = strings.ReplaceAll(installPath, "$HOME", os.Getenv("HOME"))
+
+	if err := os.MkdirAll(installPath, 0755); err != nil && !os.IsExist(err) {
+		fmt.Printf("Error creating directory %s, error: %s\n", installPath, err.Error())
+	}
+
+	if version == "" {
+		v, err := get.FindGitHubRelease("prometheus", "node_exporter")
+		if err != nil {
+			return err
+		}
+		version = v
+	} else if !strings.HasPrefix(version, "v") {
+		version = "v" + version
+	}
+
+	outFilePath, _, err := get.Download(tool, arch, osVer, version, installPath, progress, !progress)
+	if err != nil {
+		return err
+	}
+	if err = os.Chmod(outFilePath, readWriteExecuteEveryone); err != nil {
+		return err
+	}
+
+	if systemd && strings.ToLower(osVer) != "linux" {
+		return fmt.Errorf("systemd is only supported on Linux")
+	}
+
+	if systemd {
+		systemdUnit := generateUnit(outFilePath)
+		unitName := "/etc/systemd/system/node_exporter.service"
+		if err := os.WriteFile(unitName, []byte(systemdUnit), readWriteExecuteEveryone); err != nil {
+			return err
+		}
+
+		fmt.Printf("Wrote: %s\n", systemdUnit)
+
+		if _, err = executeShellCmd(context.Background(), "systemctl", "daemon-reload"); err != nil {
+			return err
+		}
+
+		if _, err = executeShellCmd(context.Background(), "systemctl", "enable", "node_exporter", "--now"); err != nil {
+			return err
+		}
+
+		fmt.Printf("Started node_exporter\n")
+
+	}
+	return nil
+}
+
+func generateUnit(outFilePath string) string {
+	return fmt.Sprintf(`[Unit]
+Description=Node Exporter
+After=network.target
+
+[Service]
+ExecStart=%s/node_exporter
+
+[Install]
+WantedBy=multi-user.target
+`, outFilePath)
+}

pkg/get/tools.go

@@ -2757,6 +2757,42 @@ https://github.com/{{.Owner}}/{{.Repo}}/releases/download/{{.Version}}/{{.Name}}
 			`,
 		})
 
+	tools = append(tools,
+		Tool{
+			Owner:       "prometheus",
+			Repo:        "node_exporter",
+			Name:        "node_exporter",
+			Description: "Prometheus exporter for monitoring server metrics",
+			URLTemplate: `
+			{{$arch := ""}}
+			{{- if eq .Arch "x86_64" -}}
+			{{$arch = "amd64"}}
+			{{- else if eq .Arch "aarch64" -}}
+			{{$arch = "arm64"}}
+			{{- else if eq .Arch "arm64" -}}
+			{{$arch = "arm64"}}
+			{{- else if eq .Arch "armv7l" -}}
+			{{ $arch = "armv7" }}
+			{{- end -}}
+
+			{{$os := ""}}
+			{{ if HasPrefix .OS "ming" -}}
+			{{$os = "windows"}}
+			{{- else if eq .OS "linux" -}}
+			{{$os = "linux"}}
+			{{- else if eq .OS "darwin" -}}
+			{{$os = "darwin"}}
+			{{- end -}}
+			https://github.com/{{.Owner}}/{{.Repo}}/releases/download/{{.Version}}/{{.Repo}}-{{.VersionNumber}}.{{$os}}-{{$arch}}.tar.gz`,
+			BinaryTemplate: `
+			{{ if HasPrefix .OS "ming" -}}
+			{{ .Name }}.exe
+			{{- else -}}
+			{{ .Name }}
+			{{- end -}}
+			`,
+		})
+
 	tools = append(tools,
 		Tool{
 			Owner:       "siderolabs",