feat: Implement Automatic Configuration Backup during re-installs or upgrades

docs/cli/newrelic_install.md

@@ -9,13 +9,17 @@ newrelic install [flags]
 ### Options
 
 ```
-  -y, --assumeYes             use "yes" for all questions during install
-  -h, --help                  help for install
-      --localRecipes string   a path to local recipes to load instead of service other fetching
-  -n, --recipe strings        the name of a recipe to install
-  -c, --recipePath strings    the path to a recipe file to install
-      --tag string            comma-separated list of tags ("key:value,key:value")
-  -t, --testMode              fakes operations for UX testing
+  -y, --assumeYes                  use "yes" for all questions during install
+      --backup-location string     custom location for backup files (default: platform-specific)
+  -h, --help                       help for install
+      --list-backups               list all available configuration backups and exit
+      --localRecipes string        a path to local recipes to load instead of service other fetching
+  -n, --recipe strings             the name of a recipe to install
+  -c, --recipePath strings         the path to a recipe file to install
+      --restore-backup string      restore configuration from a specific backup ID (e.g. backup-2026-02-19-143022)
+      --skip-backup                skip backing up existing configuration files before install
+      --tag string                 comma-separated list of tags ("key:value,key:value")
+  -t, --testMode                   fakes operations for UX testing
 ```
 
 ### Options inherited from parent commands
@@ -40,6 +44,46 @@ If no version is specified, the latest available version will be installed. This
 
 For a list of available versions, please refer to the [Infrastructure Agent Release Notes](https://docs.newrelic.com/docs/release-notes/infrastructure-release-notes/infrastructure-agent-release-notes/).
 
+### Configuration Backup
+
+Before any recipe is executed, the CLI automatically detects and backs up existing New Relic configuration files (Infrastructure agent, APM agents, Logging, Integrations). Backups are timestamped and stored in a platform-specific location:
+
+| Platform         | Default backup location            |
+|------------------|------------------------------------|
+| Linux (root)     | `/opt/.newrelic-backups/`          |
+| Linux (non-root) | `~/.newrelic-backups/`             |
+| Windows          | `%ProgramData%\.newrelic-backups\` |
+| macOS            | `~/.newrelic-backups/`             |
+
+The last 5 backups are retained automatically; older ones are removed.
+
+Each backup contains a `manifest.json` with the timestamp, list of files, SHA256 checksums, and CLI version used.
+
+**Skip backup (CI/CD environments):**
+```
+newrelic install --skip-backup
+```
+
+**Use a custom backup directory:**
+```
+newrelic install --backup-location /var/backups/newrelic
+```
+
+**List all available backups:**
+```
+newrelic install --list-backups
+```
+
+**Restore configuration from a specific backup:**
+```
+newrelic install --restore-backup backup-2026-02-19-143022
+```
+
+Use `-y` / `--assumeYes` with `--restore-backup` to skip the confirmation prompt:
+```
+newrelic install --restore-backup backup-2026-02-19-143022 --assumeYes
+```
+
 ### SEE ALSO
 
 - [newrelic](newrelic.md) - The New Relic CLI

internal/install/backup/creator.go

@@ -0,0 +1,231 @@
+package backup
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"runtime"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+)
+
+// Creator handles creating timestamped backups with checksums
+type Creator struct {
+	baseBackupDir string
+}
+
+// NewCreator creates a new backup creator
+func NewCreator(baseBackupDir string) *Creator {
+	return &Creator{
+		baseBackupDir: baseBackupDir,
+	}
+}
+
+// CreateBackup creates a timestamped backup of config files with checksums
+func (c *Creator) CreateBackup(files []string, platform string, cliVersion string) (*Result, error) {
+	if len(files) == 0 {
+		log.Debug("No files to backup")
+		return &Result{
+			Success:  true,
+			Warnings: []string{"No config files found to backup"},
+		}, nil
+	}
+
+	backupID := c.generateBackupID()
+	backupDir := filepath.Join(c.baseBackupDir, backupID)
+
+	log.WithFields(log.Fields{
+		"backupID":  backupID,
+		"backupDir": backupDir,
+		"files":     len(files),
+	}).Debug("Creating configuration backup")
+
+	// Create backup directory
+	if err := os.MkdirAll(backupDir, 0755); err != nil {
+		return &Result{
+			Success: false,
+			Error:   fmt.Errorf("failed to create backup directory: %w", err),
+		}, err
+	}
+
+	result := &Result{
+		BackupID:  backupID,
+		BackupDir: backupDir,
+		Success:   true,
+		Warnings:  []string{},
+	}
+
+	manifest := &Manifest{
+		Timestamp:  time.Now(),
+		BackupID:   backupID,
+		Platform:   platform,
+		Reason:     "guided-install",
+		CLIVersion: cliVersion,
+		Files:      []BackedUpFile{},
+	}
+
+	// Backup each file
+	for _, srcPath := range files {
+		backedUpFile, err := c.backupSingleFile(srcPath, backupDir)
+		if err != nil {
+			warning := fmt.Sprintf("Failed to backup %s: %v", srcPath, err)
+			result.Warnings = append(result.Warnings, warning)
+			log.Warn(warning)
+			continue
+		}
+
+		manifest.Files = append(manifest.Files, *backedUpFile)
+		result.FilesBackedUp++
+	}
+
+	// Write manifest
+	manifestPath, err := c.writeManifest(manifest, backupDir)
+	if err != nil {
+		result.Warnings = append(result.Warnings, fmt.Sprintf("Failed to write manifest: %v", err))
+		log.WithError(err).Warn("Failed to write backup manifest")
+	} else {
+		result.ManifestPath = manifestPath
+	}
+
+	if result.FilesBackedUp == 0 {
+		result.Success = false
+		result.Error = fmt.Errorf("no files were successfully backed up")
+		return result, result.Error
+	}
+
+	log.WithFields(log.Fields{
+		"backupID":      backupID,
+		"filesBackedUp": result.FilesBackedUp,
+		"warnings":      len(result.Warnings),
+	}).Debug("Backup completed")
+
+	return result, nil
+}
+
+// backupSingleFile backs up a single file with checksum
+func (c *Creator) backupSingleFile(srcPath string, backupDir string) (*BackedUpFile, error) {
+	// Open source file
+	srcFile, err := os.Open(srcPath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to open source file: %w", err)
+	}
+	defer func() { _ = srcFile.Close() }()
+
+	// Get file info
+	srcInfo, err := srcFile.Stat()
+	if err != nil {
+		return nil, fmt.Errorf("failed to stat source file: %w", err)
+	}
+
+	// Create destination path preserving relative structure.
+	// Strip the volume name (e.g. "C:" on Windows, "" on Unix) and the
+	// leading path separator so the result is always a relative path,
+	// otherwise filepath.Join discards the backupDir prefix entirely.
+	// e.g. Linux:   /etc/newrelic-infra.yml               → etc/newrelic-infra.yml
+	//      Windows: C:\Program Files\New Relic\newrelic-infra.yml → Program Files\New Relic\newrelic-infra.yml
+	relPath := srcPath
+	if filepath.IsAbs(srcPath) {
+		vol := filepath.VolumeName(srcPath) // "C:" on Windows, "" on Unix
+		afterVol := srcPath[len(vol):]
+		if len(afterVol) > 0 && afterVol[0] == filepath.Separator {
+			relPath = afterVol[1:]
+		} else {
+			relPath = afterVol
+		}
+	}
+	dstPath := filepath.Join(backupDir, relPath)
+
+	// Create destination directory
+	dstDir := filepath.Dir(dstPath)
+	if err := os.MkdirAll(dstDir, 0755); err != nil {
+		return nil, fmt.Errorf("failed to create destination directory: %w", err)
+	}
+
+	// Create destination file
+	dstFile, err := os.OpenFile(dstPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, srcInfo.Mode())
+	if err != nil {
+		return nil, fmt.Errorf("failed to create destination file: %w", err)
+	}
+
+	// Copy file and calculate checksum
+	checksum, size, copyErr := c.copyFileWithChecksum(srcFile, dstFile)
+	if closeErr := dstFile.Close(); closeErr != nil && copyErr == nil {
+		copyErr = fmt.Errorf("failed to close destination file: %w", closeErr)
+	}
+	if copyErr != nil {
+		return nil, fmt.Errorf("failed to copy file: %w", copyErr)
+	}
+
+	permissions := c.getFilePermissions(srcInfo)
+
+	return &BackedUpFile{
+		OriginalPath:   srcPath,
+		BackupPath:     dstPath,
+		SHA256Checksum: checksum,
+		Size:           size,
+		Permissions:    permissions,
+	}, nil
+}
+
+// copyFileWithChecksum copies a file and calculates SHA256 checksum
+func (c *Creator) copyFileWithChecksum(src io.Reader, dst io.Writer) (checksum string, size int64, err error) {
+	hash := sha256.New()
+	writer := io.MultiWriter(dst, hash)
+
+	size, err = io.Copy(writer, src)
+	if err != nil {
+		return "", 0, err
+	}
+
+	checksum = hex.EncodeToString(hash.Sum(nil))
+	return checksum, size, nil
+}
+
+// writeManifest writes the backup manifest to JSON
+func (c *Creator) writeManifest(manifest *Manifest, backupDir string) (string, error) {
+	manifestPath := filepath.Join(backupDir, "manifest.json")
+
+	jsonData, err := json.MarshalIndent(manifest, "", "  ")
+	if err != nil {
+		return "", fmt.Errorf("failed to marshal manifest: %w", err)
+	}
+
+	if err := os.WriteFile(manifestPath, jsonData, 0644); err != nil {
+		return "", fmt.Errorf("failed to write manifest file: %w", err)
+	}
+
+	log.Debugf("Manifest written to: %s", manifestPath)
+	return manifestPath, nil
+}
+
+// getFilePermissions returns a string representation of file permissions
+func (c *Creator) getFilePermissions(info os.FileInfo) string {
+	if runtime.GOOS == "windows" {
+		// Windows: simplified permission string
+		mode := info.Mode()
+		perms := ""
+		if mode&0400 != 0 {
+			perms += "R"
+		}
+		if mode&0200 != 0 {
+			perms += "W"
+		}
+		if perms == "" {
+			perms = "RO"
+		}
+		return perms
+	}
+
+	// Unix: octal permission string
+	return fmt.Sprintf("%04o", info.Mode().Perm())
+}
+
+// generateBackupID generates a timestamp-based backup ID
+func (c *Creator) generateBackupID() string {
+	return fmt.Sprintf("backup-%s", time.Now().Format("2006-01-02-150405"))
+}