Initial commit

main.go

@@ -0,0 +1,137 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"os/exec"
+	"sort"
+	"time"
+
+	"github.com/pkg/sftp"
+)
+
+const (
+	OK       = 0
+	WARNING  = 1
+	CRITICAL = 2
+	UNKNOWN  = 3
+)
+
+var (
+	warning  = flag.Duration("warning", -1, "return WARNING if the lastest snapshot is older than the specified number of hours")
+	critical = flag.Duration("critical", -1, "return CRITICAL if the lastest snapshot is older than the specified number of hours")
+	repoPath = flag.String("repository", "", "path to restic repository on sftp target")
+	sftpHost = flag.String("host", "", "ssh host to be used for sftp connection")
+	sftpUser = flag.String("user", "", "ssh user to be used for sftp connection")
+	sftpPort = flag.String("port", "22", "ssh port to be used for sftp connection")
+)
+
+func parseArgs() error {
+	flag.Parse()
+	if *warning < 0 {
+		return fmt.Errorf("The option 'warning' needs to be set and greater than 0.")
+	}
+	if *critical < 0 {
+		return fmt.Errorf("The option 'critical' needs to be set and greater than 0.")
+	}
+	if *repoPath == "" {
+		return fmt.Errorf("The option 'repository' needs to be set.")
+	}
+	if *sftpHost == "" {
+		return fmt.Errorf("The option 'host' needs to be set.")
+	}
+	if *sftpUser == "" {
+		return fmt.Errorf("The option 'user' needs to be set.")
+	}
+	if *sftpPort == "" {
+		return fmt.Errorf("The option 'port' needs to be a valid port.")
+	}
+	return nil
+}
+
+func getStatusStr(status int) string {
+	switch status {
+	case OK:
+		return "OK"
+	case WARNING:
+		return "WARNING"
+	case CRITICAL:
+		return "CRITICAL"
+	default:
+		return "UNKNOWN"
+	}
+}
+
+func main() {
+	rc, msg := mainReturnWithStatus()
+	fmt.Printf("%s: %s\n", getStatusStr(rc), msg)
+	os.Exit(rc)
+}
+
+func mainReturnWithStatus() (int, string) {
+	err := parseArgs()
+	if err != nil {
+		return UNKNOWN, err.Error()
+	}
+
+	// Connect to a remote host and request the sftp subsystem via the 'ssh'
+	// command. This assumes that passwordless login is correctly configured.
+	cmd := exec.Command("ssh", *sftpHost, "-l", *sftpUser, "-p", *sftpPort, "-s", "sftp")
+
+	// send errors from ssh to stderr
+	cmd.Stderr = os.Stderr
+
+	// get stdin and stdout
+	wr, err := cmd.StdinPipe()
+	if err != nil {
+		return UNKNOWN, err.Error()
+	}
+	rd, err := cmd.StdoutPipe()
+	if err != nil {
+		return UNKNOWN, err.Error()
+	}
+
+	// start the process
+	if err := cmd.Start(); err != nil {
+		return UNKNOWN, err.Error()
+	}
+	defer cmd.Wait()
+
+	// open the SFTP session
+	client, err := sftp.NewClientPipe(rd, wr)
+	if err != nil {
+		return UNKNOWN, err.Error()
+	}
+	defer client.Close()
+
+	// get a list of all snapshots in the restic repository
+	files, err := client.ReadDir(*repoPath + "/snapshots")
+	if err != nil {
+		return UNKNOWN, err.Error()
+	}
+
+	if len(files) == 0 {
+		return CRITICAL, "no snapshots found"
+	}
+
+	// sort snapshots by modtime
+	sort.Slice(files, func(a, b int) bool {
+		return files[b].ModTime().Before(files[a].ModTime())
+	})
+
+	age := time.Now().Sub(files[0].ModTime())
+
+	// sanity check
+	if age < 0 {
+		return CRITICAL, "latest snapshot is in the future"
+	}
+	msg := fmt.Sprintf("latest snapshot created %s ago", age.Round(time.Second))
+	if age > *critical {
+		return CRITICAL, msg
+	} else if age > *warning {
+		return WARNING, msg
+	} else {
+		return OK, msg
+	}
+}