JSch-用java实现服务器远程操作

介绍

前段时间接了一个比较特殊的需求，需要做一个用于部署服务的服务。主要是将一个k8s服务集群部署到远端的服务器上，具体服务器的连接信息会通过接口传入。

本来部署是人工来完成的，无非是将一些必须的文件scp到目标服务器上，然后ssh远程登录，执行一些安装的操作，齐活。安装的流程没什么问题，主要是这些步骤需要使用代码来实现，也就是需要一个支持SSH的client库来执行这些操作

最终选用了JSch(Java Secure Channel)，官网介绍：

JSch is a pure Java implementation of SSH2.
JSch allows you to connect to an sshd server and use port forwarding, X11 forwarding, file transfer, etc., and you can integrate its functionality into your own Java programs. JSch is licensed under BSD style license.

实现

为了完成部署服务的任务，需要解决几个问题：

• SSH连接到远端的服务器
• 在服务器上执行指令
• 使用scp命令传输文件
• 编辑服务器上的文件，主要是为了修改一些配置文件

这里介绍下几个主要的工具方法

远程ssh连接

先定义一个Remote类，用于记录服务器登录信息

@Data
public class Remote {

    private String user = "root";
    private String host = "127.0.0.1";
    private int port = 22;
    private String password = "";
    private String identity = "~/.ssh/id_rsa";
    private String passphrase = "";
}

这里填充了一些默认值，平时用的时候方便一些

JSch使用Session来定义一个远程节点：

public static Session getSession(Remote remote) throws JSchException {
    JSch jSch = new JSch();
    if (Files.exists(Paths.get(remote.getIdentity()))) {
        jSch.addIdentity(remote.getIdentity(), remote.getPassphrase());
    }
    Session session = jSch.getSession(remote.getUser(), remote.getHost(),remote.getPort());
    session.setPassword(remote.getPassword());
    session.setConfig("StrictHostKeyChecking", "no");
    return session;
}

测试一下：

public static void main(String[] args) throws Exception {
    Remote remote = new Remote();
    remote.setHost("192.168.124.20");
    remote.setPassword("123456");
    Session session = getSession(remote);
    session.connect(CONNECT_TIMEOUT);
    if (session.isConnected()) {
        System.out.println("Host({}) connected.", remote.getHost);
    }
    session.disconnect();
}

正确的输入了服务器地址和密码后，连接成功。

这里要提一下，JSch会优先使用填入的ssh_key去尝试登录，尝试失败后才会使用password登录，这点和平时使用ssh命令的交互是一致的，好评~

远程指令

接下来就是编写一个通用的方法，用于在Session上执行命令

public static List remoteExecute(Session session, String command) throws JSchException {
    log.debug(">> {}", command);
    List resultLines = new ArrayList<>();
    ChannelExec channel = null;
    try{
        channel = (ChannelExec) session.openChannel("exec");
        channel.setCommand(command);
        InputStream input = channel.getInputStream();
        channel.connect(CONNECT_TIMEOUT);
        try {
            BufferedReader inputReader = new BufferedReader(newInputStreamReader(input));
            String inputLine = null;
            while((inputLine = inputReader.readLine()) != null) {
                log.debug("   {}", inputLine);
                resultLines.add(inputLine);
            }
        } finally {
            if (input != null) {
                try {
                    input.close();
                } catch (Exception e) {
                    log.error("JSch inputStream close error:", e);
                }
            }
        }
    } catch (IOException e) {
        log.error("IOcxecption:", e);
    } finally {
        if (channel != null) {
            try {
                channel.disconnect();
            } catch (Exception e) {
                log.error("JSch channel disconnect error:", e);
            }
        }
    }
    return resultLines;
}

测试一下：

public static void main(String[] args) throws Exception {
    Remote remote = new Remote();
    remote.setHost("192.168.124.20");
    remote.setPassword("123456");
    Session session = getSession(remote);
    session.connect(CONNECT_TIMEOUT);
    if (session.isConnected()) {
        System.out.println("Host({}) connected.", remote.getHost());
    }
    
    remoteExecute(session, "pwd");
    remoteExecute(session, "mkdir /root/jsch-demo");
    remoteExecute(session, "ls /root/jsch-demo");
    remoteExecute(session, "touch /root/jsch-demo/test1; touch /root/jsch-demo/test2");
    remoteExecute(session, "echo 'It a test file.' > /root/jsch-demo/test-file");
    remoteExecute(session, "ls -all /root/jsch-demo");
    remoteExecute(session, "ls -all /root/jsch-demo | grep test");
    remoteExecute(session, "cat /root/jsch-demo/test-file");
    
    session.disconnect();
}

执行后，日志输出如下内容：

Host(192.168.124.20) connected.
>> pwd
   /root
>> mkdir /root/jsch-demo
>> ls /root/jsch-demo
>> touch /root/jsch-demo/test1; touch /root/jsch-demo/test2
>> echo 'It a test file.' > /root/jsch-demo/test-file
>> ls -all /root/jsch-demo
   total 12
   drwxr-xr-x 2 root root 4096 Jul 30 03:05 .
   drwx------ 6 root root 4096 Jul 30 03:05 ..
   -rw-r--r-- 1 root root    0 Jul 30 03:05 test1
   -rw-r--r-- 1 root root    0 Jul 30 03:05 test2
   -rw-r--r-- 1 root root   16 Jul 30 03:05 test-file
>> ls -all /root/jsch-demo | grep test
   -rw-r--r-- 1 root root    0 Jul 30 03:05 test1
   -rw-r--r-- 1 root root    0 Jul 30 03:05 test2
   -rw-r--r-- 1 root root   16 Jul 30 03:05 test-file
>> cat /root/jsch-demo/test-file
   It a test file.

执行结果令人满意，这些常见的命令都成功了
再次好评~

scp操作

scp操作官方给了很详细的示例scpTo+scpFrom，再次好评~
scpTo:

public static long scpTo(String source, Session session, String destination) {
    FileInputStream fileInputStream = null;
    try {
        ChannelExec channel = (ChannelExec) session.openChannel("exec");
        OutputStream out = channel.getOutputStream();
        InputStream in = channel.getInputStream();
        boolean ptimestamp = false;
        String command = "scp";
        if (ptimestamp) {
            command += " -p";
        }
        command += " -t " + destination;
        channel.setCommand(command);
        channel.connect(CONNECT_TIMEOUT);
        if (checkAck(in) != 0) {
            return -1;
        }
        File _lfile = new File(source);
        if (ptimestamp) {
            command = "T " + (_lfile.lastModified() / 1000) + " 0";
            // The access time should be sent here,
            // but it is not accessible with JavaAPI ;-<
            command += (" " + (_lfile.lastModified() / 1000) + " 0\n");
            out.write(command.getBytes());
            out.flush();
            if (checkAck(in) != 0) {
                return -1;
            }
        }
        //send "C0644 filesize filename", where filename should not include '/'
        long fileSize = _lfile.length();
        command = "C0644 " + fileSize + " ";
        if (source.lastIndexOf('/') > 0) {
            command += source.substring(source.lastIndexOf('/') + 1);
        } else {
            command += source;
        }
        command += "\n";
        out.write(command.getBytes());
        out.flush();
        if (checkAck(in) != 0) {
            return -1;
        }
        //send content of file
        fileInputStream = new FileInputStream(source);
        byte[] buf = new byte[1024];
        long sum = 0;
        while (true) {
            int len = fileInputStream.read(buf, 0, buf.length);
            if (len <= 0) {
                break;
            }
            out.write(buf, 0, len);
            sum += len;
        }
        //send '\0'
        buf[0] = 0;
        out.write(buf, 0, 1);
        out.flush();
        if (checkAck(in) != 0) {
            return -1;
        }
        return sum;
    } catch(JSchException e) {
        log.error("scp to catched jsch exception, ", e);
    } catch(IOException e) {
        log.error("scp to catched io exception, ", e);
    } catch(Exception e) {
        log.error("scp to error, ", e);
    } finally {
        if (fileInputStream != null) {
            try {
                fileInputStream.close();
            } catch (Exception e) {
                log.error("File input stream close error, ", e);
            }
        }
    }
    return -1;
}

scpFrom:

public static long scpFrom(Session session, String source, String destination) {
    FileOutputStream fileOutputStream = null;
    try {
        ChannelExec channel = (ChannelExec) session.openChannel("exec");
        channel.setCommand("scp -f " + source);
        OutputStream out = channel.getOutputStream();
        InputStream in = channel.getInputStream();
        channel.connect();
        byte[] buf = new byte[1024];
        //send '\0'
        buf[0] = 0;
        out.write(buf, 0, 1);
        out.flush();
        while(true) {
            if (checkAck(in) != 'C') {
                break;
            }
        }
        //read '644 '
        in.read(buf, 0, 4);
        long fileSize = 0;
        while (true) {
            if (in.read(buf, 0, 1) < 0) {
                break;
            }
            if (buf[0] == ' ') {
                break;
            }
            fileSize = fileSize * 10L + (long)(buf[0] - '0');
        }
        String file = null;
        for (int i = 0; ; i++) {
            in.read(buf, i, 1);
            if (buf[i] == (byte) 0x0a) {
                file = new String(buf, 0, i);
                break;
            }
        }
        // send '\0'
        buf[0] = 0;
        out.write(buf, 0, 1);
        out.flush();
        // read a content of lfile
        if (Files.isDirectory(Paths.get(destination))) {
            fileOutputStream = new FileOutputStream(destination + File.separator +file);
        } else {
            fileOutputStream = new FileOutputStream(destination);
        }
        long sum = 0;
        while (true) {
            int len = in.read(buf, 0 , buf.length);
            if (len <= 0) {
                break;
            }
            sum += len;
            if (len >= fileSize) {
                fileOutputStream.write(buf, 0, (int)fileSize);
                break;
            }
            fileOutputStream.write(buf, 0, len);
            fileSize -= len;
        }
        return sum;
    } catch(JSchException e) {
        log.error("scp to catched jsch exception, ", e);
    } catch(IOException e) {
        log.error("scp to catched io exception, ", e);
    } catch(Exception e) {
        log.error("scp to error, ", e);
    } finally {
        if (fileOutputStream != null) {
            try {
                fileOutputStream.close();
            } catch (Exception e) {
                log.error("File output stream close error, ", e);
            }
        }
    }
    return -1;
}

另外还有一个公用的方法checkAck:

private static int checkAck(InputStream in) throws IOException {
    int b=in.read();
    // b may be 0 for success,
    //          1 for error,
    //          2 for fatal error,
    //          -1
    if(b==0) return b;
    if(b==-1) return b;
    if(b==1 || b==2){
        StringBuffer sb=new StringBuffer();
        int c;
        do {
            c=in.read();
            sb.append((char)c);
        }
        while(c!='\n');
        if(b==1){ // error
            log.debug(sb.toString());
        }
        if(b==2){ // fatal error
            log.debug(sb.toString());
        }
    }
    return b;
}

测试一下：
我们在项目根目录下新建一个文件test.txt

public static void main(String[] args) throws Exception {
    Remote remote = new Remote();
    remote.setHost("192.168.124.20");
    remote.setPassword("123456");
    Session session = getSession(remote);
    session.connect(CONNECT_TIMEOUT);
    if (session.isConnected()) {
        log.debug("Host({}) connected.", remote.getHost());
    }
    
    remoteExecute(session, "ls /root/jsch-demo/");
    scpTo("test.txt", session, "/root/jsch-demo/");
    remoteExecute(session, "ls /root/jsch-demo/");
    remoteExecute(session, "echo ' append text.' >> /root/jsch-demo/test.txt");
    scpFrom(session, "/root/jsch-demo/test.txt", "file-from-remote.txt");
    
    session.disconnect();
}

日志输出如下：
而且可以看到项目目录下出现了一个文件file-from-remote.txt。里面的内容比原先的test.txt多了 append text

Host(192.168.124.20) connected.
>> ls /root/jsch-demo/
   test1
   test2
   test-file
>> ls /root/jsch-demo/
   test1
   test2
   test-file
   test.txt
>> echo ' append text.' >> /root/jsch-demo/test.txt

远程编辑

我们平时在服务器上编辑文件一般使用vi，非常方便，但是在这里操作vi就有点复杂了
最后采用的方案是，先将源文件备份，然后scp拉到本地，编辑完后scp回原位置
remoteEdit方法：

private static boolean remoteEdit(Session session, String source, Function, List> process) {
    InputStream in = null;
    OutputStream out = null;
    try {
        String fileName = source;
        int index = source.lastIndexOf('/');
        if (index >= 0) {
            fileName = source.substring(index + 1);
        }
        //backup source
        remoteExecute(session, String.format("cp %s %s", source, source + ".bak." +System.currentTimeMillis()));
        //scp from remote
        String tmpSource = System.getProperty("java.io.tmpdir") + session.getHost() +"-" + fileName;
        scpFrom(session, source, tmpSource);
        in = new FileInputStream(tmpSource);
        //edit file according function process
        String tmpDestination = tmpSource + ".des";
        out = new FileOutputStream(tmpDestination);
        List inputLines = new ArrayList<>();
        BufferedReader reader = new BufferedReader(new InputStreamReader(in));
        String inputLine = null;
        while ((inputLine = reader.readLine()) != null) {
            inputLines.add(inputLine);
        }
        List outputLines = process.apply(inputLines);
        for (String outputLine : outputLines) {
            out.write((outputLine + "\n").getBytes());
            out.flush();
        }
        //scp to remote
        scpTo(tmpDestination, session, source);
        return true;
    } catch (Exception e) {
        log.error("remote edit error, ", e);
        return false;
    } finally {
        if (in != null) {
            try {
                in.close();
            } catch (Exception e) {
                log.error("input stream close error", e);
            }
        }
        if (out != null) {
            try {
                out.close();
            } catch (Exception e) {
                log.error("output stream close error", e);
            }
        }
    }
}

测试一下：

public static void main(String[] args) throws Exception {
    Remote remote = new Remote();
    remote.setHost("192.168.124.20");
    remote.setPassword("123456");
    Session session = getSession(remote);
    session.connect(CONNECT_TIMEOUT);
    if (session.isConnected()) {
        log.debug("Host({}) connected.", remote.getHost());
    }
    
    remoteExecute(session, "echo 'It a test file.' > /root/jsch-demo/test");
    remoteExecute(session, "cat /root/jsch-demo/test");
    remoteEdit(session, "/root/jsch-demo/test", (inputLines) -> {
        List outputLines = new ArrayList<>();
        for (String inputLine : inputLines) {
            outputLines.add(inputLine.toUpperCase());
        }
        return outputLines;
    });
    remoteExecute(session, "cat /root/jsch-demo/test");
    
    session.disconnect();
}

执行后日志输出：

Host(192.168.124.20) connected.
>> echo 'It a test file.' > /root/jsch-demo/test
>> cat /root/jsch-demo/test
   It a test file.
>> cp /root/jsch-demo/test /root/jsch-demo/test.bak.1564556060191
>> cat /root/jsch-demo/test
   IT A TEST FILE.

可以看到字母已经都是大写了

总结

上面这些方法，基本上覆盖了我们日常在服务器上进行操作的场景了，那么不管部署服务，还是运维服务器都不成问题了