Check for dependencies before installing

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

cmd/install.go

@@ -0,0 +1,86 @@
+package cmd
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"path"
+	"path/filepath"
+	"text/template"
+
+	"github.com/spf13/cobra"
+)
+
+var installCmd = &cobra.Command{
+	Use:   "install",
+	Short: "Install faasd",
+	RunE:  runInstall,
+}
+
+func runInstall(_ *cobra.Command, _ []string) error {
+
+	err := binExists("/usr/local/bin/", "faas-containerd")
+	if err != nil {
+		return err
+	}
+
+	err = binExists("/usr/local/bin/", "netns")
+	if err != nil {
+		return err
+	}
+
+	err = installUnit("faas-containerd")
+	if err != nil {
+		return err
+	}
+
+	err = installUnit("faasd")
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func binExists(folder, name string) error {
+	findPath := path.Join(folder, name)
+	if _, err := os.Stat(findPath); err != nil {
+		return fmt.Errorf("unable to stat %s, install this binary before continuing", findPath)
+	}
+	return nil
+}
+
+func installUnit(name string) error {
+
+	tmpl, err := template.ParseFiles("./hack/" + name + ".service")
+
+	wd, _ := os.Getwd()
+	var tpl bytes.Buffer
+	userData := struct {
+		Cwd string
+	}{
+		Cwd: wd,
+	}
+
+	err = tmpl.Execute(&tpl, userData)
+	if err != nil {
+		return err
+	}
+
+	err = writeUnit(name+".service", tpl.Bytes())
+
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func writeUnit(name string, data []byte) error {
+	f, err := os.Create(filepath.Join("/lib/systemd/system", name))
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	_, err = f.Write(data)
+	return err
+}

cmd/root.go

@@ -22,6 +22,7 @@ const WelcomeMessage = "Welcome to faasd"
 func init() {
 	rootCommand.AddCommand(versionCmd)
 	rootCommand.AddCommand(upCmd)
+	rootCommand.AddCommand(installCmd)
 }
 
 var rootCommand = &cobra.Command{

hack/faas-containerd.service

@@ -0,0 +1,12 @@
+[Unit]
+Description=faasd-containerd
+
+[Service]
+MemoryLimit=500M
+ExecStart="/usr/local/bin/faas-containerd"
+Restart=on-failure
+RestartSec=10s
+WorkingDirectory="/usr/local/bin/"
+
+[Install]
+WantedBy=multi-user.target

hack/faasd.service

@@ -0,0 +1,13 @@
+[Unit]
+Description=faasd
+After=faas-containerd.service
+
+[Service]
+MemoryLimit=500M
+ExecStart={{.Cwd}}/faasd up
+Restart=on-failure
+RestartSec=10s
+WorkingDirectory={{.Cwd}}
+
+[Install]
+WantedBy=multi-user.target