Linux 應用程序開發入門

Neo Chen?(netkiller)

<openunix@163.com>

版權 ? 2011, 2012 http://netkiller.github.com

摘要

我會實現一個守護進程，從這個程序你將了解，Linux 應用程序開發基本流程

我們將實現一個遠程shell的功能，可以通過tcp協議，運行遠程機器上的命令或shell腳本

通過這個命令可以實現批量操作，管理上千臺服務器。需要發揮你的想象力，靈活使用它。

寫這個腳本，我是為了替代SSH遠程操作，因為SSH不能控制運行命令，操作風險大，也不安全。

程序還不完善，還需要很多后續改進工作，比如通過SSL建立Socket鏈接，用戶認證，ACL訪問控制等等.

下面是我多年積累下來的經驗總結，整理成文檔供大家參考:

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Netkiller Architect 手札	Netkiller Linux 手札	Netkiller Developer 手札	Netkiller Database 手札
Netkiller Debian 手札	Netkiller CentOS 手札	Netkiller FreeBSD 手札	Netkiller Shell 手札
Netkiller Web 手札	Netkiller Monitoring 手札	Netkiller Storage 手札	Netkiller Mail 手札
Netkiller Security 手札	Netkiller PostgreSQL 手札	Netkiller MySQL 手札	Netkiller LDAP 手札
Netkiller Cryptography 手札	Netkiller Intranet 手札	Netkiller Cisco IOS 手札	Netkiller Writer 手札
Netkiller Version 手札	Netkiller Studio Linux 手札	?	?

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目錄

1. 環境2. nodekeeper 主程序2.1. 幫助信息2.2. 參數處理2.3. 后臺運行2.4. 日志記錄2.5. 多線程3. 配置文件4. init.d 腳本4.1. start/stop4.2. service start/stop

1.?環境

OS: Ubuntu 10.10

Python: 3.2.2

程序目錄: /srv/nodekeeper

目錄與相關文件

$ 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 <openunix@163.com> ##############################################import asyncore, asynchat, socket, threading import subprocess, os, sys, getopt, configparser, logging import string, re from multiprocessing import Processclass Backend(asyncore.dispatcher):queue = []def __init__(self, host, port,config):asyncore.dispatcher.__init__(self)self.host = hostself.port = portself.config = configself.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):passdef 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 = resourceself.buffer = b''self.set_terminator(b"\r\n")self.logging = resource.loggingself.protocols = resource.protocolsself.sections = resource.sectionsself.host = self.sessions.hostdef handle_connect(self):# connection succeeded#self.logging.info('')passdef handle_expt(self):# connection failedself.close()def collect_incoming_data(self, data):"""Buffer the data"""#self.buffer.append(data)self.buffer = datadef 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] + ' ' + parameterscreen = 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 = Noneagreement = Nonedef __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.agreementdef 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.agreementdef main():daemon = Falsehost = 'localhost'port = 7800pidfile = ''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 = Trueelif o in ("-h", "--host"):host = aelif o in ("-p", "--port"):port = int(a)elif o in ("--basedir"):BASEDIR = aelif o in ("--pidfile"):pidfile = aelif o in ("--config"):cfgfile = aelif o in ("--protocol"):protocol = a elif o in ("--logfile"):logfile = aelse: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 parentsys.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<openunix@163.com>. ")# 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.?幫助信息

usage()

Usage: nodekeeper -d -h <ip address> -p <7800> Development and deployment administration platformMandatory 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 7800nodekeeper -d -h localhost -p 7800See http://netkiller.sf.net/ for updates, bug reports, and answers, if you have no web access, by sending email to Neo Chan<openunix@163.com>.

2.2.?參數處理

getopt.getopt 實現Unix風格的命令參數，例如:

nodekeeper --daemon --host localhost --port 7800--host localhost --port 7800 IP地址與端口參數 --daemon 參數實現后臺運行

具體實現代碼

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 = Trueelif o in ("-h", "--host"):host = aelif o in ("-p", "--port"):port = int(a)elif o in ("--basedir"):BASEDIR = aelif o in ("--pidfile"):pidfile = aelif o in ("--config"):cfgfile = aelif o in ("--protocol"):protocol = a elif o in ("--logfile"):logfile = aelse:assert False, "unhandled option"except getopt.GetoptError as err:# print help information and exit:usage()sys.exit(2)

2.3.?后臺運行

--daemon 參數實現后臺運行，原理是首先通過os.fork()克隆一個進程，然后退出當前進程，克隆的新進程繼續運行

如果是Shell程序，你可使用“&”符號后臺運行，但作為一個應用程序，使用“&”顯得不專業。

具體實現的代碼如下

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

程序一旦進入后臺，當前進程即將關閉，所以你必須保存PID，為后面的推出程序操作使用，這里我們可以通過 --pidfile 指定一個pid文件

2.4.?日志記錄

程序一旦進入后臺，你只能通過ps，pstree, top 等命令查看狀態，運行情況必須通過日志的形式，打印出來

具體實現代碼如下：

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.?多線程

繼承 asynchat.async_chat 實現多線程

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

連接數限制

self.listen(10)

可以將這個參數提出來，然后通過命令行設置。

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

Linux 所有守護進程都是用init.d下面的腳本來管理

當人你也可以直接運行命令：

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

但這樣只能算是一個半成品，也不夠專業，我們寫的是linux運用程序，必須遵循Linux規范，所有要實現一個init.d腳本

$ cat nodekeeper #! /bin/sh### BEGIN INIT INFO # Provides: nodekeeper # Required-Start: $local_fs $remote_fs $network $syslog # Required-Stop: $local_fs $remote_fs $network $syslog # Default-Start: 2 3 4 5 # Default-Stop: 0 1 6 # Short-Description: starts the nodekeeper web server # Description: starts nodekeeper using start-stop-daemon ### END INIT INFOPATH=/srv/nodekeeper/bin:$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.cfgDAEMON_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 fiset -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" instart)echo -n "Starting $DESC: "start-stop-daemon --start --quiet --pidfile /var/run/$NAME.pid \--exec $DAEMON -- $DAEMON_OPTS || trueecho "$NAME.";;stop)echo -n "Stopping $DESC: "start-stop-daemon --stop --quiet --pidfile /var/run/$NAME.pid \--exec $DAEMON || trueecho "$NAME.";;restart|force-reload)echo -n "Restarting $DESC: "start-stop-daemon --stop --quiet --pidfile \/var/run/$NAME.pid --exec $DAEMON || truesleep 1start-stop-daemon --start --quiet --pidfile \/var/run/$NAME.pid --exec $DAEMON -- $DAEMON_OPTS || trueecho "$NAME.";;reload)echo -n "Reloading $DESC configuration: "start-stop-daemon --stop --signal HUP --quiet --pidfile /var/run/$NAME.pid \--exec $DAEMON || trueecho "$NAME.";;configtest)echo -n "Testing $DESC configuration: "if test_nodekeeper_configthenecho "$NAME."elseexit $?fi;;status)status_of_proc -p /var/run/$NAME.pid "$DAEMON" nodekeeper && exit 0 || exit $?;;*)echo "Usage: $NAME {start|stop|restart|reload|force-reload|status|configtest}" >&2exit 1;; esacexit 0

我們將使用DAEMON_OPTS變量，提供所有需要的參數

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

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