更新ssh-agent和直接指定私钥登录方式共存，更新文档

README.md

@@ -53,7 +53,8 @@ AB两台服务器中的项目均将日志写到文件系统的`/home/data/logs/l
     #tail_flags="--retry --follow=name"
 
     # 服务器配置,可以配置多个
-    # 如果不提供password,则使用当前用户的ssh公钥,建议采用该方式,使用密码方式不安全
+    # 如果不提供 password, 则默认使用系统配置的 ssh-agent 设置，
+    # 你也可以通过指定 private_key_path 配置项来指定使用特定的私钥来登录 (private_key_path=/home/mylxsw/.ssh/id_rsa)
     # server_name, hostname, user 配置为必选,其它可选
     [servers]
 

go.mod

@@ -1,5 +1,7 @@
 module github.com/mylxsw/remote-tail
 
+go 1.14
+
 require (
 	github.com/BurntSushi/toml v0.3.1
 	golang.org/x/crypto v0.0.0-20190325154230-a5d413f7728c

go.sum

@@ -2,4 +2,5 @@ github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 golang.org/x/crypto v0.0.0-20190325154230-a5d413f7728c h1:Vj5n4GlwjmQteupaxJ9+0FNOmBrHfq7vN4btdGoDZgI=
 golang.org/x/crypto v0.0.0-20190325154230-a5d413f7728c/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a h1:1BGLXjeY4akVXGgbC9HugT3Jv3hCI0z56oJR5vAMgBU=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=

ssh/ssh.go

@@ -20,53 +20,57 @@ type Client struct {
 	*ssh.Client
 }
 
-func (this *Client) Connect() error {
+func (sshClient *Client) Connect() error {
 
 	conf := ssh.ClientConfig{
-		User:            this.User,
+		User:            sshClient.User,
 		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
 	}
-	if this.Password != "" {
-		conf.Auth = append(conf.Auth, ssh.Password(this.Password))
-	} else {
-		socket := os.Getenv("SSH_AUTH_SOCK")//if occcur error "Failed to open SSH_AUTH_SOCK: dial unix: missing address" , excute command: eval `ssh-agent`,and enter passphrase
+	if sshClient.Password != "" {
+		conf.Auth = append(conf.Auth, ssh.Password(sshClient.Password))
+	} else if sshClient.PrivateKeyPath != "" {
+		privateKey, err := getPrivateKey(sshClient.PrivateKeyPath)
+		if err != nil {
+			return err
+		}
 
-		conn, err := net.Dial("unix", socket)
+		conf.Auth = append(conf.Auth, privateKey)
+	} else {
+		// if occur error "Failed to open SSH_AUTH_SOCK: dial unix: missing address",
+		// execute command: eval `ssh-agent`,and enter passphrase
+		conn, err := net.Dial("unix", os.Getenv("SSH_AUTH_SOCK"))
 		if err != nil {
 			log.Fatalf("Failed to open SSH_AUTH_SOCK: %v", err)
 		}
 
 		agentClient := agent.NewClient(conn)
-
-		if err != nil {
-			return err
-		}
-		conf.Auth = append(conf.Auth,
-			// Use a callback rather than PublicKeys so we only consult the
-			// agent once the remote server wants it.
-			ssh.PublicKeysCallback(agentClient.Signers),
-		)
+		// Use a callback rather than PublicKeys so we only consult the
+		// agent once the remote server wants it.
+		conf.Auth = append(conf.Auth, ssh.PublicKeysCallback(agentClient.Signers))
 	}
-	client, err := ssh.Dial("tcp", this.Host, &conf)
+	client, err := ssh.Dial("tcp", sshClient.Host, &conf)
 
 	if err != nil {
 		return fmt.Errorf("unable to connect: %v", err)
 	}
 
-	this.Client = client
+	sshClient.Client = client
 
 	return nil
 }
 
 // Close the connection
-func (this *Client) Close() {
-	this.Client.Close()
+func (sshClient *Client) Close() {
+	sshClient.Client.Close()
 }
 
 // Get the private key for current user
 func getPrivateKey(privateKeyPath string) (ssh.AuthMethod, error) {
-	if privateKeyPath == "" {
-		privateKeyPath = filepath.Join(os.Getenv("HOME"), ".ssh/id_rsa")
+	if !fileExist(privateKeyPath) {
+		defaultPrivateKeyPath := filepath.Join(os.Getenv("HOME"), ".ssh/id_rsa")
+		log.Printf("Warning: private key path [%s] does not exist, using default %s instead", privateKeyPath, defaultPrivateKeyPath)
+
+		privateKeyPath = defaultPrivateKeyPath
 	}
 
 	key, err := ioutil.ReadFile(privateKeyPath)
@@ -89,3 +93,12 @@ func CreateTerminalModes() *ssh.TerminalModes {
 		ssh.TTY_OP_OSPEED: 14400,
 	}
 }
+
+func fileExist(path string) bool {
+	_, err := os.Stat(path)
+	if err != nil && os.IsNotExist(err) {
+		return false
+	}
+
+	return true
+}