Self-Updating CLI Tool

Build a command-line tool that can update itself automatically with version checking.

85 min

Advanced

GoRustPython

Overview

In this example, we'll create a command-line tool that can check for updates and replace itself with a new version when available. This is particularly useful for distributing tools that need to stay up-to-date.

Key Features

Version checking against a remote repository
Secure binary verification
Atomic updates to prevent corruption
Cross-platform compatibility
Clean rollback on failed updates

Implementation Steps

Version Checking
Implement a function to check the current version against a remote version endpoint.
Download New Version
Securely download the new binary to a temporary location.
Verification
Verify the downloaded binary's checksum and signature.
Atomic Replacement
Replace the current binary with the new version in an atomic operation.
Restart
Restart the application with the new version if needed.

Example Code (Go)

package main

import (
  "crypto/sha256"
  "fmt"
  "io"
  "net/http"
  "os"
  "os/exec"
  "path/filepath"
  "runtime"
)

func checkForUpdate(currentVersion string) (bool, string, error) {
  // Implementation would check a remote endpoint
  // and return if an update is available with the new version
  return false, "", nil
}

func downloadUpdate(version string) (string, error) {
  // Implementation would download the new binary
  return "", nil
}

func verifyChecksum(filePath, expectedChecksum string) bool {
  // Implementation would verify the file's checksum
  return true
}

func replaceBinary(newBinaryPath string) error {
  // Implementation would replace the current binary
  return nil
}

func main() {
  currentVersion := "1.0.0"
  
  updateAvailable, newVersion, err := checkForUpdate(currentVersion)
  if err != nil {
    fmt.Printf("Error checking for updates: %v
", err)
    return
  }
  
  if updateAvailable {
    fmt.Printf("Updating to version %s...
", newVersion)
    
    // Download and verify new version
    tempPath, err := downloadUpdate(newVersion)
    if err != nil {
      fmt.Printf("Error downloading update: %v
", err)
      return
    }
    
    // Replace current binary
    if err := replaceBinary(tempPath); err != nil {
      fmt.Printf("Error applying update: %v
", err)
      return
    }
    
    fmt.Println("Update completed successfully!")
  } else {
    fmt.Println("Already up to date!")
  }
}

Concepts Covered

Auto-UpdatesVersion ManagementBinary Distribution