Linux 应用程序开发入门

Linux 应用程序开发入门

Mr. Neo Chen (netkiller), 陈景峰(BG7NYT)

中国广东省深圳市龙华新区民治街道溪山美地
518131
+86 13113668890
+86 755 29812080
<[email protected]>

版权 © 2011, 2012, 2013 http://netkiller.github.com

$Date: 2012-02-01 14:03:53 +0800 (Wed, 01 Feb 2012) $

摘要

我会实现一个守护进程，从这个程序你将了解，Linux 应用程序开发基本流程

我们将实现一个远程shell的功能，可以通过tcp协议，运行远程机器上的命令或shell脚本

通过这个命令可以实现批量操作，管理上千台服务器。需要发挥你的想象力，灵活使用它。

写这个脚本，我是为了替代SSH远程操作，因为SSH不能控制运行命令，操作风险大，也不安全。

程序还不完善，还需要很多后续改进工作，比如通过SSL建立Socket链接，用户认证，ACL访问控制等等.

我的系列文档

Netkiller Architect 手札	Netkiller Developer 手札	Netkiller Testing 手札	Netkiller Cryptography 手札	Netkiller Version 手札
Netkiller Linux 手札	Netkiller Debian 手札	Netkiller CentOS 手札	Netkiller FreeBSD 手札	Netkiller Security 手札
Netkiller Web 手札	Netkiller Monitoring 手札	Netkiller Storage 手札	Netkiller Mail 手札	Netkiller Shell 手札
Netkiller Database 手札	Netkiller PostgreSQL 手札	Netkiller MySQL 手札	Netkiller NoSQL 手札	Netkiller LDAP 手札
Netkiller Cisco IOS 手札	Netkiller Intranet 手札	Netkiller Multimedia 手札	Netkiller Docbook 手札	Netkiller 开源软件 手札

目录

1. 环境 2. nodekeeper 主程序 2.1. 帮助信息 2.2. 参数处理 2.3. 后台运行 2.4. 日志记录 2.5. 多线程 3. 配置文件 4. init.d 脚本 4.1. start/stop 4.2. service start/stop

1. 环境

OS: Ubuntu 11.10

Python: 3.2.2

程序目录: /srv/nodekeeper

目录与相关文件

$ cd /srv
$ find nodekeeper | grep -v .svn
nodekeeper
nodekeeper/nodekeeper.ubuntu
nodekeeper/nodekeeper.cenos
nodekeeper/etc
nodekeeper/etc/commands.cfg
nodekeeper/etc/protocol.cfg
nodekeeper/bin
nodekeeper/bin/nodekeeper
nodekeeper/bin/console

2. nodekeeper 主程序

$ cat nodekeeper/bin/nodekeeper
#!/usr/bin/env python3
#/bin/env python3
#-*- coding: utf-8 -*-
##############################################
# Home  : http://netkiller.sf.net
# Author: Neo <[email protected]>
##############################################

import asyncore, asynchat, socket, threading
import subprocess, os, sys, getopt, configparser, logging
import string, re
from multiprocessing import Process

class Backend(asyncore.dispatcher):
    queue = []
    def __init__(self, host, port,config):
        asyncore.dispatcher.__init__(self)

        self.host = host
        self.port = port
        self.config = config

        self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
        self.bind((host,port))
        self.listen(10)

        try:
            cfg = Protocol(config['protocol'], self.host)
            #self.protocols = cfg.items(self.host)
            self.protocols = cfg.all()
            self.sections = cfg.sections()
        except configparser.NoSectionError as err:
            print("Error: %s %s" %(err, config['protocol']))
            sys.exit(2)
        try:
            logging.basicConfig(level=logging.NOTSET,
                    format='%(asctime)s %(levelname)-8s %(message)s',
                    datefmt='%Y-%m-%d %H:%M:%S',
                    filename=config['logfile'],
                    filemode='a')
            self.logging = logging.getLogger()
            #self.logging.debug('Test')
        except AttributeError as err:
            print("Error: %s %s" %(err, config['logfile']))
            sys.exit(2)

    def handle_accept (self):
        conn, addr = self.accept()
        self.queue.append(addr)
        request_handler(conn, self)
    def handle_connect(self):
        pass
    def handle_expt(self):
        self.close()
    def handle_close(self):
        self.close()

class request_handler(asynchat.async_chat):

    def __init__(self, sock, resource):
        asynchat.async_chat.__init__(self, sock=sock)
        self.sessions = resource
        self.buffer = b''
        self.set_terminator(b"\r\n")
        self.logging 	= resource.logging
        self.protocols 	= resource.protocols
        self.sections 	= resource.sections
        self.host 	= self.sessions.host

    def handle_connect(self):
        # connection succeeded
        #self.logging.info('')
        pass

    def handle_expt(self):
        # connection failed
        self.close()

    def collect_incoming_data(self, data):
        """Buffer the data"""
        #self.buffer.append(data)
        self.buffer = data

    def found_terminator(self):
        try:
            buffer = bytes.decode(self.buffer)
        except UnicodeDecodeError:
            print("\r\nError: ",err)
            buffer = ''
        try:
            execute = re.split(' ', buffer)
            command = execute[0]
            parameter = ' '.join( execute[1:])
            response = b''
            screen = ''
            if self.buffer == b'quit' or self.buffer == b'exit' :
                self.push(b'shutdown!!!\r\n')
                self.close_when_done()
            elif self.buffer == b'help' or self.buffer == b'?':
                screen = "Help may be requested at any point in a command by entering a question mark '?' or 'help'. the help list will be showing the available options.\r\n"
            
                for cmd,v in self.protocols :
                    screen += cmd + "\r\n"
            elif self.buffer == b'sections' :
                for sect in self.sections :
                    screen += sect + "\r\n"
            elif self.buffer == b'help.html' :
                for cmd,v in self.protocols :
                    screen += '<a href="?host='+self.host+'&cmd='+cmd+'">'+ cmd +'</a><br />' + "\r\n"
            elif self.buffer == b'enable':
                self.prompt = b'#'
            elif self.buffer == b'end' or self.buffer == b'^z':
                self.prompt = b'>'
            else:
                proto = dict(self.protocols)
                if command in proto :
                    run = proto[command] + ' ' + parameter
                    screen = subprocess.getoutput(run)
    
            if screen :
                response = bytes(screen + "\r\n",'utf8')
                self.push(response)
                self.logging.info(bytes.decode(self.buffer))
            self.buffer = b''
            self.close_when_done()
        except :
            self.close_when_done()
            sys.exit(2)

class Protocol():
    config = None
    agreement = None
    def __init__(self,cfg = 'protocol.cfg',sections = ''):
        self.config = configparser.SafeConfigParser()
        self.config.read(cfg)
        #self.agreement = self.config.items('common')
    def sections(self):
        return self.config.sections()
    def items(self, sections):
        self.agreement = self.config.items(sections)
        return self.agreement
    def dicts(self):
        return dict(self.agreement)
    def all(self):
        self.agreement = []
        for section in self.config.sections():
            self.agreement += self.config.items(section)
        return self.agreement


def main():
    daemon = False
    host = 'localhost'
    port = 7800
    pidfile = ''
    logfile = ''
    cfgfile = ''

    try:
        opts, args = getopt.getopt(sys.argv[1:], "h:p:d?v", [ "daemon","host=","port=", 'help',"h=","p=", "basedir=", "pidfile=", "config=", "protocol=", "logfile="])

        if not opts :
            usage()
            sys.exit()
        for o, a in opts :
            if o in ('-?', '--help') :
                usage()
                sys.exit()
            elif o in ("-v", "--verbose"):
                usage()
                sys.exit()
            elif o in ("-d", "--daemon"):
                daemon = True
            elif o in ("-h", "--host"):
                host = a
            elif o in ("-p", "--port"):
                port = int(a)
            elif o in ("--basedir"):
                BASEDIR = a
            elif o in ("--pidfile"):
                pidfile = a
            elif o in ("--config"):
                cfgfile = a
            elif o in ("--protocol"):
                protocol = a		
            elif o in ("--logfile"):
                logfile = a
            else:
                assert False, "unhandled option"
    except getopt.GetoptError as err:
        # print help information and exit:
        usage()
        sys.exit(2)

    try:

        if daemon :
            pid = os.fork()
            if pid > 0:
                #exit first parent
                sys.exit(0)
        myself = str(sys.argv[0].split('/')[-1:][0])
        #pidfile = os.getpid()
        if not pidfile :
            pidfile = '/var/run/'+myself+'.pid'
        file = open(pidfile,'w')
        file.write(str(os.getpid()))
        file.close()
        if not cfgfile :
            cfgfile = ''+myself+'.cfg'
        if not logfile :
            logfile = '/var/log/'+myself+'.log'
        config = dict({'cfgfile':cfgfile, 'pidfile':pidfile, 'logfile':logfile, 'protocol':protocol})

        Backend(host,port,config)
        asyncore.loop(timeout=30, use_poll=True)

    except socket.error as err:
        print("\r\nError: ",err)
        sys.exit(2)
    except IOError as err:
        print("\r\nError: ",err)
        sys.exit(2)

def usage():
    myself = str(sys.argv[0].split('/')[-1:][0])

    print("Usage: %s -d -h <ip address> -p <7800>" % myself );
    print("Development and deployment administration platform")
    print("\r\nMandatory arguments to long options are mandatory for short options too.")
    print("\t-?, --help")
    print("\t-v, --verbose")
    print("\t-d, --daemon")
    print("\t-h, --host \t\t(default localhost)")
    print("\t-p, --port")
    print("\t    --config \t\t(default %s.cfg)" % myself)
    print("\t    --protocol \t\t(default %s.cfg)" % "protocol.cfg")
    print("\t    --pidfile \t\t(default /var/run/%s.pid)" % myself)
    print("\t    --logfile \t\t(default /var/log/%s.log)" % myself)
    print("\r\nExample:")
    print("\t%s --daemon --host localhost --port 7800" % myself)
    print("\t%s -d -h localhost -p 7800" % myself)
    print("\r\nSee http://netkiller.sf.net/ for updates, bug reports, and answers, \r\nif you have no web access, by sending email to Neo Chan<[email protected]>. ")
    # Exit status is 0 if OK, 1 if minor problems, 2 if serious trouble.

if __name__ == '__main__':
    try:
        main()
    except KeyboardInterrupt:
        print ("Crtl+C Pressed. Shutting down.")

2.1. 帮助信息

usage()

Usage: nodekeeper -d -h <ip address> -p <7800>
Development and deployment administration platform

Mandatory arguments to long options are mandatory for short options too.
	-?, --help
	-v, --verbose
	-d, --daemon
	-h, --host 		(default localhost)
	-p, --port
	    --config 		(default nodekeeper.cfg)
	    --protocol 		(default protocol.cfg.cfg)
	    --pidfile 		(default /var/run/nodekeeper.pid)
	    --logfile 		(default /var/log/nodekeeper.log)

Example:
	nodekeeper --daemon --host localhost --port 7800
	nodekeeper -d -h localhost -p 7800

See http://netkiller.sf.net/ for updates, bug reports, and answers, 
if you have no web access, by sending email to Neo Chan<[email protected]>.

2.2. 参数处理

getopt.getopt 实现Unix风格的命令参数，例如:

nodekeeper --daemon --host localhost --port 7800

--host localhost --port 7800 IP地址与端口参数
--daemon 参数实现后台运行

具体实现代码

try:
        opts, args = getopt.getopt(sys.argv[1:], "h:p:d?v", [ "daemon","host=","port=", 'help',"h=","p=", "basedir=", "pidfile=", "config=", "protocol=", "logfile="])

        if not opts :
            usage()
            sys.exit()
        for o, a in opts :
            if o in ('-?', '--help') :
                usage()
                sys.exit()
            elif o in ("-v", "--verbose"):
                usage()
                sys.exit()
            elif o in ("-d", "--daemon"):
                daemon = True
            elif o in ("-h", "--host"):
                host = a
            elif o in ("-p", "--port"):
                port = int(a)
            elif o in ("--basedir"):
                BASEDIR = a
            elif o in ("--pidfile"):
                pidfile = a
            elif o in ("--config"):
                cfgfile = a
            elif o in ("--protocol"):
                protocol = a		
            elif o in ("--logfile"):
                logfile = a
            else:
                assert False, "unhandled option"
    except getopt.GetoptError as err:
        # print help information and exit:
        usage()
        sys.exit(2)

2.3. 后台运行

--daemon 参数实现后台运行，原理是首先通过os.fork()克隆一个进程，然后退出当前进程，克隆的新进程继续运行

如果是Shell程序，你可使用“&”符号后台运行，但作为一个应用程序，使用“&”显得不专业。

具体实现的代码如下

if daemon :
            pid = os.fork()
            if pid > 0:
                #exit first parent
                sys.exit(0)

程序一旦进入后台，当前进程即将关闭，所以你必须保存PID，为后面的推出程序操作使用，这里我们可以通过 --pidfile 指定一个pid文件

2.4. 日志记录

程序一旦进入后台，你只能通过ps，pstree, top 等命令查看状态，运行情况必须通过日志的形式，打印出来

具体实现代码如下：

logging.basicConfig(level=logging.NOTSET,
                    format='%(asctime)s %(levelname)-8s %(message)s',
                    datefmt='%Y-%m-%d %H:%M:%S',
                    filename=config['logfile'],
                    filemode='a')
            self.logging = logging.getLogger()
            self.logging.debug('Test')

2.5. 多线程

继承 asynchat.async_chat 实现多线程

class request_handler(asynchat.async_chat):

    def __init__(self, sock, resource):
        asynchat.async_chat.__init__(self, sock=sock)

连接数限制

self.listen(10)

可以将这个参数提出来，然后通过命令行设置。

nodekeeper --daemon --maxconn 100 --host localhost --port 7800
			
self.max_connect = maxconn

self.listen(self.max_connect)

3. 配置文件

$ cat nodekeeper/etc/protocol.cfg 
[system]
ls = ls
os.hosts = cat /etc/hosts
os.issue = cat /etc/issue
os.memory = free
os.who = who
os.harddisk = df -h
os.uptime = uptime
os.cpuinfo = cat /proc/cpuinfo
os.meminfo = cat /proc/meminfo
os.dmesg = dmesg
os.process = ps aux
os.summary = echo
network.status = netstat -n | awk '/^tcp/ {++S[$NF]} END {for(a in S) print a, S[a]}'
network.netstat = netstat -nlp
network.ifconfig = ifconfig
network.route = ip route

[apache]
apache.start = /usr/local/apache/bin/apachectl start
apache.stop = /usr/local/apache/bin/apachectl stop
apache.restart = /usr/local/apache/bin/apachectl restart
apache.status = ps ax |grep httpd
apache.conf = cat /usr/local/apache/conf/httpd.conf
apache.conf.vhost = cat /usr/local/apache/conf/extra/httpd-vhosts.conf
apache.logs.now = 
apache.logs.tail = 

[resin]
resin.start = /usr/local/resin/bin/httpd.sh start
resin.stop = /usr/local/resin/bin/httpd.sh stop
resin.restart = /usr/local/resin/bin/httpd.sh restart
resin.status = /usr/local/resin/bin/httpd.sh status
resin.conf = cat /usr/local/resin/conf/resin.conf

[www]
www.list = ls -1 /www
www.permission = find /www -type d -exec chmod 755 {} \; find /www -type f -exec chmod 644 {} \; 
www.permission.777 = chmod 777 -R /www/*
lamp.status = ps ax |grep -E "mysqld|httpd|resin"

[samba]
samba.start = /etc/init.d/smb start
samba.stop = /etc/init.d/smb stop
samba.restart = /etc/init.d/smb restart
samba.status = /etc/init.d/smb status

[mysql]
mysql.start = /etc/init.d/mysql start
mysql.stop = /etc/init.d/mysql stop
mysql.restart = /etc/init.d/mysql restart

[memcache]
memcache.start = /etc/init.d/memcache start
memcache.stop = /etc/init.d/memcache stop
memcache.restart = /etc/init.d/memcache restart

[vsftpd]
vsftpd.start = /etc/init.d/vsftpd start
vsftpd.stop = /etc/init.d/vsftpd stop
vsftpd.restart = /etc/init.d/vsftpd restart
vsftpd.status = /etc/init.d/vsftpd status

4. init.d 脚本

Linux 所有守护进程都是用init.d下面的脚本来管理

当人你也可以直接运行命令：

nodekeeper --daemon --host localhost --port 7800

但这样只能算是一个半成品，也不够专业，我们写的是linux运用程序，必须遵循Linux规范，所有要实现一个init.d脚本

$ cat nodekeeper
#! /bin/sh

### BEGIN INIT INFO
# Provides:          nodekeeper
# Required-Start:    $local_fs $remote_fs $network $syslog
# Required-Stop:     $local_fs $remote_fs $network $syslog
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: starts the nodekeeper web server
# Description:       starts nodekeeper using start-stop-daemon
### END INIT INFO

PATH=/srv/nodekeeper/bin:$PATH
DAEMON=/srv/nodekeeper/bin/nodekeeper
NAME=nodekeeper
DESC=nodekeeper
BASEDIR="/srv/nodekeeper"
HOST=$(ifconfig  | grep 'inet addr:'| grep -v '127.0.0.1' | cut -d: -f2 | awk '{ print $1}'|head -n 1)
PORT=7800
CONFIG=$BASEDIR/etc/$NAME.cfg
LOGFILE=$BASEDIR/log/$NAME.log
PIDFILE=$BASEDIR/run/$NAME.pid
PIDFILE=/var/run/$NAME.pid
PROTOCOL=$BASEDIR/etc/protocol.cfg

DAEMON_OPTS="--daemon --host $HOST --port $PORT --config=$CONFIG --protocol=$PROTOCOL --pidfile=$PIDFILE --logfile=$LOGFILE"

test -x $DAEMON || exit 0

# Include nodekeeper defaults if available
if [ -f /etc/default/nodekeeper ] ; then
	. /etc/default/nodekeeper
fi

set -e

. /lib/lsb/init-functions

#test_nodekeeper_config() {
#  if $DAEMON -t $DAEMON_OPTS >/dev/null 2>&1
#  then
#    return 0
#  else
#    $DAEMON -t $DAEMON_OPTS
#    return $?
#  fi
#}

case "$1" in
  start)
	echo -n "Starting $DESC: "
	start-stop-daemon --start --quiet --pidfile /var/run/$NAME.pid \
		--exec $DAEMON -- $DAEMON_OPTS || true
	echo "$NAME."
	;;
  stop)
	echo -n "Stopping $DESC: "
	start-stop-daemon --stop --quiet --pidfile /var/run/$NAME.pid \
		--exec $DAEMON || true
	echo "$NAME."
	;;
  restart|force-reload)
	echo -n "Restarting $DESC: "
	start-stop-daemon --stop --quiet --pidfile \
		/var/run/$NAME.pid --exec $DAEMON || true
	sleep 1

	start-stop-daemon --start --quiet --pidfile \
		/var/run/$NAME.pid --exec $DAEMON -- $DAEMON_OPTS || true
	echo "$NAME."
	;;
  reload)
        echo -n "Reloading $DESC configuration: "

        start-stop-daemon --stop --signal HUP --quiet --pidfile /var/run/$NAME.pid \
            --exec $DAEMON || true
        echo "$NAME."
        ;;
  configtest)
        echo -n "Testing $DESC configuration: "
        if test_nodekeeper_config
        then
          echo "$NAME."
        else
          exit $?
        fi
        ;;
  status)
	status_of_proc -p /var/run/$NAME.pid "$DAEMON" nodekeeper && exit 0 || exit $?
	;;
  *)
	echo "Usage: $NAME {start|stop|restart|reload|force-reload|status|configtest}" >&2
	exit 1
	;;
esac

exit 0

我们将使用DAEMON_OPTS变量，提供所有需要的参数

DAEMON_OPTS="--daemon --host $HOST --port $PORT --config=$CONFIG --protocol=$PROTOCOL --pidfile=$PIDFILE --logfile=$LOGFILE"

4.1. start/stop

/etc/init.d/nodekeeper start
/etc/init.d/nodekeeper stop

4.2. service start/stop

service nodekeeper start
service nodekeeper stop