[sftp] add support

.golangci.yml

@@ -277,6 +277,7 @@ linters:
         - ^github.com/urfave/cli.v3.ArgumentBase$
         - ^github.com/urfave/cli.v3.Command$
         - ^github.com/urfave/cli.v3.FlagBase$
+        - ^golang.org/x/crypto/ssh.+Config$
         - ^golang.org/x/tools/go/analysis.Analyzer$
         - ^google.golang.org/protobuf/.+Options$
         - ^gopkg.in/telebot.v4.LongPoller$

README.md

@@ -40,7 +40,7 @@
 <h3 align="center">sftp-sync</h3>
 
   <p align="center">
-    A command-line utility for syncing a local folder with a remote FTP server on every change of files or directories.
+    A command-line utility for syncing a local folder with a remote FTP or SFTP server on every change of files or directories.
     <br />
     <br />
     <a href="https://github.com/capcom6/sftp-sync/issues/new?labels=bug&template=bug-report---.md">Report Bug</a>
@@ -78,13 +78,14 @@
 
 <!-- [![Product Name Screen Shot][product-screenshot]](https://example.com) -->
 
-sftp-sync is a command-line utility for syncing a local folder with a remote FTP server on every change of files or directories.
+sftp-sync is a command-line utility for syncing a local folder with a remote FTP or SFTP server on every change of files or directories.
 
 ### Features
 
-- Continuous synchronization: Automatically syncs local changes to the remote FTP server whenever files or directories are added, modified, or deleted.
+- Continuous synchronization: Automatically syncs local changes to the remote FTP or SFTP server whenever files or directories are added, modified, or deleted.
 - Exclude paths: Allows you to exclude specific paths from being synced.
 - Easy to use: Simple and intuitive command-line interface.
+- Protocol support: Supports both FTP and SFTP (SSH File Transfer Protocol).
 
 <p align="right">(<a href="#readme-top">back to top</a>)</p>
 
@@ -153,11 +154,32 @@ The binary will be available in the `bin/` directory.
 ## Usage
 Run the `sftp-sync` command with the necessary options and arguments:
 
+**FTP:**
 ```shell
 sftp-sync --dest=ftp://username:password@hostname:port/path/to/remote/folder \
   --exclude=.git /path/to/local/folder
 ```
 
+**SFTP (password):**
+```shell
+sftp-sync --dest=sftp://username:password@hostname:22/path/to/remote/folder \
+  --exclude=.git /path/to/local/folder
+```
+
+**SFTP (SSH key):**
+```shell
+sftp-sync --dest="sftp://username@hostname:22/path/to/remote/folder?key=~/.ssh/id_ed25519" \
+  --exclude=.git /path/to/local/folder
+```
+
+**SFTP (SSH agent):**
+```shell
+sftp-sync --dest="sftp://username@hostname:22/path/to/remote/folder?agent=true" \
+  --exclude=.git /path/to/local/folder
+```
+
+> **Note:** SFTP uses SSH port 22 by default (vs FTP port 21).
+
 ### Environment Variables
 
 - `DEBUG`: When set to any value, enables debug mode (equivalent to `--debug` flag).
@@ -169,7 +191,24 @@ sftp-sync --dest=ftp://username:password@hostname:port/path/to/remote/folder \
 
 ### Sync Command Options
 
-- `--dest`: The destination FTP server URL. It should follow the format `ftp://username:password@hostname:port/path/to/remote/folder`.
+- `--dest`: The destination server URL. Supports both FTP and SFTP:
+  - FTP: `ftp://username:password@hostname:port/path/to/remote/folder`
+  - SFTP (password): `sftp://username:password@hostname:22/path/to/remote/folder`
+  - SFTP (SSH key): `sftp://username@hostname:22/path?key=~/.ssh/id_ed25519`
+  - SFTP (SSH key with passphrase): `sftp://username@hostname:22/path?key=~/.ssh/id_ed25519&key_pass=secret`
+  - SFTP (SSH agent): `sftp://username@hostname:22/path?agent=true`
+
+The URL path (e.g., `/path/to/remote/folder`) is used as the remote destination prefix. All synced files and directories are placed relative to this path. **The remote directory must already exist** before starting the sync.
+
+SFTP URL query parameters:
+
+| Parameter  | Description                                                                                                                             | Example                 |
+| ---------- | --------------------------------------------------------------------------------------------------------------------------------------- | ----------------------- |
+| `key`      | Path to SSH private key file (supports `~` expansion). If omitted, auto-detects `~/.ssh/id_ed25519`, `~/.ssh/id_ecdsa`, `~/.ssh/id_rsa` | `key=~/.ssh/custom_key` |
+| `key_pass` | Passphrase for encrypted private keys                                                                                                   | `key_pass=mysecret`     |
+| `agent`    | Use SSH agent for authentication when set to `true`                                                                                     | `agent=true`            |
+
+Authentication methods are tried in order: SSH agent → private key → password.
 - `--exclude`: (Optional) Specifies paths or glob patterns to exclude from synchronization. Supports `*`, `**`, and `?`. You can specify multiple `--exclude` options.
 
 ### Sync Command Arguments
@@ -196,7 +235,7 @@ The application uses structured error handling with specific exit codes:
 ## Roadmap
 
 - [x] Support for patterns in the `--exclude` option.
-- [ ] Support of Secure FTP (SFTP) protocol.
+- [x] Support of Secure FTP (SFTP) protocol.
 - [ ] Improved error handling and error messages.
 - [ ] Integration with Git for automatic syncing on commit or branch changes.
 - [ ] Integration with Git for linking branch to remote server.

go.mod

@@ -1,20 +1,23 @@
 module github.com/capcom6/sftp-sync
 
-go 1.24.3
+go 1.25.0
 
 require (
 	github.com/bmatcuk/doublestar/v4 v4.10.0
 	github.com/fsnotify/fsnotify v1.6.0
 	github.com/go-core-fx/cli-logger v0.0.0-20260319073231-90ee4649c242
 	github.com/jlaffaye/ftp v0.2.0
 	github.com/joho/godotenv v1.5.1
+	github.com/pkg/sftp v1.13.10
 	github.com/samber/lo v1.52.0
 	github.com/urfave/cli/v3 v3.7.0
+	golang.org/x/crypto v0.51.0
 )
 
 require (
 	github.com/hashicorp/errwrap v1.1.0 // indirect
 	github.com/hashicorp/go-multierror v1.1.1 // indirect
-	golang.org/x/sys v0.12.0 // indirect
-	golang.org/x/text v0.22.0 // indirect
+	github.com/kr/fs v0.1.0 // indirect
+	golang.org/x/sys v0.44.0 // indirect
+	golang.org/x/text v0.37.0 // indirect
 )

go.sum

@@ -15,6 +15,10 @@ github.com/jlaffaye/ftp v0.2.0 h1:lXNvW7cBu7R/68bknOX3MrRIIqZ61zELs1P2RAiA3lg=
 github.com/jlaffaye/ftp v0.2.0/go.mod h1:is2Ds5qkhceAPy2xD6RLI6hmp/qysSoymZ+Z2uTnspI=
 github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
 github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
+github.com/kr/fs v0.1.0 h1:Jskdu9ieNAYnjxsi0LbQp1ulIKZV1LAFgK1tWhpZgl8=
+github.com/kr/fs v0.1.0/go.mod h1:FFnZGqtBN9Gxj7eW1uZ42v5BccTP0vu6NEaFoC2HwRg=
+github.com/pkg/sftp v1.13.10 h1:+5FbKNTe5Z9aspU88DPIKJ9z2KZoaGCu6Sr6kKR/5mU=
+github.com/pkg/sftp v1.13.10/go.mod h1:bJ1a7uDhrX/4OII+agvy28lzRvQrmIQuaHrcI1HbeGA=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/samber/lo v1.52.0 h1:Rvi+3BFHES3A8meP33VPAxiBZX/Aws5RxrschYGjomw=
@@ -23,10 +27,14 @@ github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu
 github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
 github.com/urfave/cli/v3 v3.7.0 h1:AGSnbUyjtLiM+WJUb4dzXKldl/gL+F8OwmRDtVr6g2U=
 github.com/urfave/cli/v3 v3.7.0/go.mod h1:ysVLtOEmg2tOy6PknnYVhDoouyC/6N42TMeoMzskhso=
+golang.org/x/crypto v0.51.0 h1:IBPXwPfKxY7cWQZ38ZCIRPI50YLeevDLlLnyC5wRGTI=
+golang.org/x/crypto v0.51.0/go.mod h1:8AdwkbraGNABw2kOX6YFPs3WM22XqI4EXEd8g+x7Oc8=
 golang.org/x/sys v0.0.0-20220908164124-27713097b956/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.12.0 h1:CM0HF96J0hcLAwsHPJZjfdNzs0gftsLfgKt57wWHJ0o=
-golang.org/x/sys v0.12.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/text v0.22.0 h1:bofq7m3/HAFvbF51jz3Q9wLg3jkvSPuiZu/pD1XwgtM=
-golang.org/x/text v0.22.0/go.mod h1:YRoo4H8PVmsu+E3Ou7cqLVH8oXWIHVoX0jqUWALQhfY=
+golang.org/x/sys v0.44.0 h1:ildZl3J4uzeKP07r2F++Op7E9B29JRUy+a27EibtBTQ=
+golang.org/x/sys v0.44.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
+golang.org/x/term v0.43.0 h1:S4RLU2sB31O/NCl+zFN9Aru9A/Cq2aqKpTZJ6B+DwT4=
+golang.org/x/term v0.43.0/go.mod h1:lrhlHNdQJHO+1qVYiHfFKVuVioJIheAc3fBSMFYEIsk=
+golang.org/x/text v0.37.0 h1:Cqjiwd9eSg8e0QAkyCaQTNHFIIzWtidPahFWR83rTrc=
+golang.org/x/text v0.37.0/go.mod h1:a5sjxXGs9hsn/AJVwuElvCAo9v8QYLzvavO5z2PiM38=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

internal/cli/commands/sync/sync.go

@@ -16,7 +16,7 @@ import (
 func Command() *cli.Command {
 	return &cli.Command{
 		Name:  "sync",
-		Usage: "watch a local folder for changes and sync them to a remote FTP server.",
+		Usage: "watch a local folder for changes and sync them to a remote FTP or SFTP server.",
 		Arguments: []cli.Argument{
 			&cli.StringArg{
 				Name:      "source",
@@ -29,7 +29,7 @@ func Command() *cli.Command {
 		Flags: []cli.Flag{
 			&cli.StringFlag{
 				Name:     "dest",
-				Usage:    "destination FTP server URL",
+				Usage:    "destination FTP/SFTP server URL (e.g., ftp://user:pass@host/path or sftp://user:pass@host:22/path)",
 				Required: true,
 			},
 			&cli.StringSliceFlag{

internal/client/client.go

@@ -5,6 +5,9 @@ import (
 	"fmt"
 	"net/url"
 
+	"github.com/capcom6/sftp-sync/internal/client/ftp"
+	"github.com/capcom6/sftp-sync/internal/client/sftp"
+	"github.com/capcom6/sftp-sync/internal/client/types"
 	logger "github.com/go-core-fx/cli-logger"
 )
 
@@ -24,9 +27,12 @@ func New(address string, log logger.Logger) (Client, error) {
 		return nil, fmt.Errorf("failed to parse URL: %w", err)
 	}
 
-	if u.Scheme == "ftp" {
-		return NewFtpClient(address, log.WithContext("client", "")), nil
+	switch u.Scheme {
+	case "ftp":
+		return ftp.NewClient(address, log.WithContext("ftp", "")), nil
+	case "sftp":
+		return sftp.NewClient(address, log.WithContext("sftp", "")), nil
 	}
 
-	return nil, fmt.Errorf("%w: %s", ErrUnsupportedScheme, u.Scheme)
+	return nil, fmt.Errorf("%w: %s (supported: ftp, sftp)", types.ErrUnsupportedScheme, u.Scheme)
 }

internal/client/ftp.go → internal/client/ftp/ftp.go

@@ -1,4 +1,4 @@
-package client
+package ftp
 
 import (
 	"context"
@@ -10,12 +10,13 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/capcom6/sftp-sync/internal/client/types"
 	logger "github.com/go-core-fx/cli-logger"
 	"github.com/jlaffaye/ftp"
 	"github.com/samber/lo"
 )
 
-type FtpClient struct {
+type Client struct {
 	url string
 
 	logger logger.Logger
@@ -24,8 +25,8 @@ type FtpClient struct {
 	lock   sync.Mutex
 }
 
-func NewFtpClient(url string, logger logger.Logger) *FtpClient {
-	return &FtpClient{
+func NewClient(url string, logger logger.Logger) *Client {
+	return &Client{
 		url: url,
 
 		logger: logger,
@@ -35,7 +36,7 @@ func NewFtpClient(url string, logger logger.Logger) *FtpClient {
 	}
 }
 
-func (c *FtpClient) init(ctx context.Context) error {
+func (c *Client) init(ctx context.Context) error {
 	c.lock.Lock()
 	defer c.lock.Unlock()
 
@@ -59,33 +60,40 @@ func (c *FtpClient) init(ctx context.Context) error {
 	}
 
 	if u.Scheme != "ftp" {
-		return fmt.Errorf("%w: %s", ErrUnsupportedScheme, u.Scheme)
+		return fmt.Errorf("%w: %s", types.ErrUnsupportedScheme, u.Scheme)
 	}
 
-	c.client, err = ftp.Dial(u.Host, ftp.DialWithContext(ctx))
+	conn, err := ftp.Dial(u.Host, ftp.DialWithContext(ctx))
 	if err != nil {
 		return fmt.Errorf("can't connect to %s: %w", u.Host, err)
 	}
 
-	password, ok := u.User.Password()
-	if !ok {
-		password = ""
+	user := u.User
+	if user == nil || user.Username() == "" {
+		_ = conn.Quit()
+		return fmt.Errorf("%w: missing FTP username in URL", types.ErrInvalidParams)
 	}
-
-	if loginErr := c.client.Login(u.User.Username(), password); loginErr != nil {
-		return fmt.Errorf("can't login as %s: %w", u.User.Username(), loginErr)
+	password, _ := user.Password()
+	if loginErr := conn.Login(user.Username(), password); loginErr != nil {
+		_ = conn.Quit()
+		return fmt.Errorf("can't login as %s: %w", user.Username(), loginErr)
 	}
 
-	if chErr := c.client.ChangeDir(u.Path); chErr != nil {
-		return fmt.Errorf("can't change directory to %s: %w", u.Path, chErr)
+	if u.Path != "" && u.Path != "/" {
+		if chErr := conn.ChangeDir(u.Path); chErr != nil {
+			_ = conn.Quit()
+			return fmt.Errorf("remote path %s does not exist or is not accessible: %w", u.Path, chErr)
+		}
 	}
 
+	c.client = conn
+
 	return nil
 }
 
-func (c *FtpClient) ping(_ context.Context) error {
+func (c *Client) ping(_ context.Context) error {
 	if c.client == nil {
-		return ErrClientIsNil
+		return types.ErrClientIsNil
 	}
 
 	if err := c.client.NoOp(); err != nil {
@@ -95,7 +103,7 @@ func (c *FtpClient) ping(_ context.Context) error {
 	return nil
 }
 
-func (c *FtpClient) MakeDir(ctx context.Context, remotePath string) error {
+func (c *Client) MakeDir(ctx context.Context, remotePath string) error {
 	if err := c.init(ctx); err != nil {
 		return err
 	}
@@ -117,7 +125,7 @@ func (c *FtpClient) MakeDir(ctx context.Context, remotePath string) error {
 	return nil
 }
 
-func (c *FtpClient) RemoveDir(ctx context.Context, remotePath string) error {
+func (c *Client) RemoveDir(ctx context.Context, remotePath string) error {
 	if err := c.init(ctx); err != nil {
 		return err
 	}
@@ -133,7 +141,7 @@ func (c *FtpClient) RemoveDir(ctx context.Context, remotePath string) error {
 	return nil
 }
 
-func (c *FtpClient) UploadFile(ctx context.Context, remotePath string, localPath string) error {
+func (c *Client) UploadFile(ctx context.Context, remotePath string, localPath string) error {
 	if err := c.init(ctx); err != nil {
 		return err
 	}
@@ -156,7 +164,7 @@ func (c *FtpClient) UploadFile(ctx context.Context, remotePath string, localPath
 	return nil
 }
 
-func (c *FtpClient) RemoveFile(ctx context.Context, remotePath string) error {
+func (c *Client) RemoveFile(ctx context.Context, remotePath string) error {
 	if err := c.init(ctx); err != nil {
 		return err
 	}
@@ -169,7 +177,7 @@ func (c *FtpClient) RemoveFile(ctx context.Context, remotePath string) error {
 	return nil
 }
 
-func (c *FtpClient) Remove(ctx context.Context, remotePath string) error {
+func (c *Client) Remove(ctx context.Context, remotePath string) error {
 	if err := c.init(ctx); err != nil {
 		return err
 	}

internal/client/ftp/ftp_test.go

@@ -0,0 +1,41 @@
+package ftp_test
+
+import (
+	"net/url"
+	"testing"
+)
+
+func TestURLPathExtraction(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name     string
+		rawURL   string
+		wantPath string
+	}{
+		{
+			name:     "nested path",
+			rawURL:   "ftp://user:pass@host:21/uploads/project/files",
+			wantPath: "/uploads/project/files",
+		},
+		{name: "single directory", rawURL: "ftp://user:pass@host:21/data", wantPath: "/data"},
+		{name: "root path", rawURL: "ftp://user:pass@host:21/", wantPath: "/"},
+		{name: "no trailing slash", rawURL: "ftp://user@host:21/path", wantPath: "/path"},
+		{name: "with port", rawURL: "ftp://user:pass@host:2121/path/to/dir", wantPath: "/path/to/dir"},
+		{name: "empty path", rawURL: "ftp://user:pass@host:21", wantPath: ""},
+		{name: "path with special chars", rawURL: "ftp://user:pass@host:21/my%20folder", wantPath: "/my folder"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			u, err := url.Parse(tt.rawURL)
+			if err != nil {
+				t.Fatalf("url.Parse(%q) error = %v", tt.rawURL, err)
+			}
+			if u.Path != tt.wantPath {
+				t.Errorf("path = %q, want %q", u.Path, tt.wantPath)
+			}
+		})
+	}
+}