Operate the server remotely more gracefully: the practice of paramiko Library

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author ： Software quality assurance
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As a test , If you ask what tools you deal with more in your work , Presumably most people will not hesitate to say server .

Test environment construction 、 Code deployment 、 The problem location log query is inseparable from the operation server . We usually log in to the server to operate the service , Then switch to the corresponding log directory , adopt grep/tail Way to query the logs we want . Of course, there are also many clients on the market to assist us in operating the server , for example xshell/xftp, But even with the client , It is still impossible to minimize our manual pipeline operation . Therefore, this paper introduces an efficient Python library Paramiko, Help you develop your own log query tool .

Paramiko What can be done

paramiko yes Python A library written in language , follow SSH2 agreement , Support the connection of remote server in the way of encryption and authentication , utilize paramiko, It can be done conveniently SSH Connect the server and file transfer between servers .

Paramiko Some basic nouns in ：

1. Channel： It's kind of safe SSH Transmission channel ;

2. Transport： When used, an encrypted Tunnels( passageway ), This Tunnels be called Channel;

3. Session： yes Client And Server Keep connected objects , use connect()/start_client()/start_server() Open a session .

How to use Paramiko

Paramiko Provide a wealth of API For our use , This section mainly introduces several commonly used API And how to use it .

pip config set global.index-url https://mirrors.aliyun.com/pypi/simple/pip install paramiko

1. Establishing a connection

paramiko.connect Detailed explanation of method parameters ：

• connect Common parameters

• hostname Connected target host

• port=SSH_PORT Designated port

• username=None The verified user name

• password=None Authenticated user password

• pkey=None Private key mode is used for authentication

• key_filename=None A file name or list of files , Specify private key file

• timeout=None Optional tcp Connection timeout

• allow_agent=True, Allow connection to ssh agent , The default is True allow

• look_for_keys=True Whether in ~/.ssh Search for private key file , The default is True allow

• compress=False, Whether to turn on compression

Method 1 、 Password connection server

import paramikofrom paramiko import SSHClient​def connect_with_password(host, username, password):  ssh = paramiko.SSHClient()  #  Auto add policy , Save the host name and key information of the server , If you do not add , So it's no longer local know_hosts The host recorded in the file will not be able to connect   ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())  ssh.load_system_host_keys()  ssh.connect(host, username=username,              password=password)  session = ssh.get_transport().open_session()  AgentRequestHandler(session)  ssh_stdin, ssh_stdout, ssh_stderr = session.exec_command("ls -l")  content = ssh_stdout.read()  return session

Method 2 、 Key connection server

def connect_with_RSAKey(host, username, file):  #  Configure private key file location   private = paramiko.RSAKey.from_private_key_file(file)  # private = paramiko.RSAKey.from_private_key_file('/Users/qa/.ssh/id_rsa')  ssh = paramiko.SSHClient()  ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())  #  Connect SSH Server side , Authenticate with user name and password   ssh.connect(hostname=host, port=22, username=username, pkey=private)  session = ssh.get_transport().open_session()  AgentRequestHandler(session)  ssh_stdin, ssh_stdout, ssh_stderr = session.exec_command("ls -l")  content = ssh_stdout.read()  return session

2. Carry out orders

Use exec_command Executing the command will return three messages ：

1、 Standard inputs （ Used to implement interactive commands ）--stdin

2、 standard output （ Save the normal execution result of the command ）--stdout

3、 Standard error output （ Save the error message of the command ）--stderr

# Defined function ssh, Write the operation contents into the function def ssh_exe_cmd(host, username, password, content):    session = connect_with_password(host, username, password)    # Use exec_command Method to execute the command , And use variables to receive the return value of the command and use print Output     stdin, stdout, stderr = session.exec_command(content)    return stdout.read()

3. Upload and download

Like we use xshell Executing instructions on the server is the same as querying logs , We can be like xftp Upload and download files on the server .

# File download def download_file_ftp(host, username, password, local_path, remote_path):    # Create with the server ssh Connect ,transport Methods establish channels , Write server information in tuples     ssh_ftp = paramiko.Transport((host, 60317))    ssh_ftp.connect(username=username, password=password)    # After creating a connection , Use sftpclient Classes and from_transport( In parentheses, write the one created above Transport passageway ) Based on the above ssh Create a connection sftp Connect , Defined as ftp_client Variables are easy to reference     ftp_client = paramiko.SFTPClient.from_transport(ssh_ftp)    # Download the file     #ftp_client.get(" Target file ", r" Save the location , Write file name ")    ftp_client.get(remote_path, local_path)    # close ssh Connect     ssh_ftp.close()​    # Upload files def upload_file_ftp(host, username, password, local_path, remote_path):    # Create with the server ssh Connect ,transport Methods establish channels , Pause server information in tuples     ssh_ftp = paramiko.Transport((host, 60317))    ssh_ftp.connect(username=username, password=password)    # After creating a connection , Use sftpclient Classes and from_transport( In parentheses, write the one created above Transport passageway ) Based on the above ssh Create a connection sftp Connect , Defined as ftp_client Variables are easy to reference     ftp_client = paramiko.SFTPClient.from_transport(ssh_ftp)    # Upload files     ftp_client.put(local_path, remote_path)    # close ssh Connect     ssh_ftp.close()

be based on Paramiko Develop log query tools

The implementation principle is very simple , Is to automatically disconnect the server （ logon server ） Part of , The execution tool automatically connects to the server , Users only need to enter the log query instruction . The complete code is as follows ：

# -*- coding: utf-8 -*-# @Author : qualityassurance# @Email : [email protected]# @File : ParamikoUtil.py# @Time : 2022/7/3 11:13​import paramikofrom paramiko.agent import AgentRequestHandler​host = ''port = ''username = ''password = ''​def connect_with_password(host, port, username, password):    """ Connect to server ,Client = paramiko.SSHClient()    """    ssh = paramiko.SSHClient()    try:        ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())        ssh.load_system_host_keys()        ssh.connect(host, port=port, username=username,                    password=password)    except Exception as e:        print(e)    return ssh​​def ssh_exe_cmd(client, cmd):    """ Return the command result executed remotely ：stdin, stdout, stderr (stdout) and decode Output ...    """    stdin, stdout, stderr = client.exec_command(cmd)    print(stdout.read().decode())    return stdout​​def main():    """ Set remote execution Linux Operation command input ..."""    client = connect_with_password(host, port, username, password)    while True:        cmd = input(" Enter the command to be executed ( Empty to exit )：").strip()        if cmd == "":            return False        else:            ssh_exe_cmd(client, cmd)​if __name__ == "__main__":    main()

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