zabbix源代码阅读--zabbix_agent

        zabbix是一个实时监控系统,可以监控服务器的运行状态(cpu,内存,端口),并且可以发送报警邮件和短信,或者执行远程命令.由于工作上需要对zabbix进行二次开发,所以借此机会阅读了一下zabbix的源代码.zabbix前台是php实现的,后台是用c写的,按功能分为几个部分:agent,server,proxy,sender. zabbix_agent负责收集机器上的数据（比如cpu利用率，内存剩余量等）发送给zabbix_server,zabbix_server负责收集zabbix_agent或者zabbix_proxy发送过来的数据，更新数据库，而前台的php代码就可以从数据库内拿出这些数据进行显示。

先看zabbix_agent，它默认会启动三个进程：collector_thread、listener_thread、active_checks_thread

/* start the collector thread */thread_args = (zbx_thread_args_t *)zbx_malloc(NULL, sizeof(zbx_thread_args_t));thread_args->thread_num = thread_num;thread_args->args = NULL;threads[thread_num++] = zbx_thread_start(collector_thread, thread_args);/* start listeners */for (i = 0; i < CONFIG_ZABBIX_FORKS; i++){thread_args = (zbx_thread_args_t *)zbx_malloc(NULL, sizeof(zbx_thread_args_t));thread_args->thread_num = thread_num;thread_args->args = &listen_sock;threads[thread_num++] = zbx_thread_start(listener_thread, thread_args);}/* start active check */if (0 == CONFIG_DISABLE_ACTIVE){activechk_args.host = CONFIG_HOSTS_ALLOWED;activechk_args.port = (unsigned short)CONFIG_SERVER_PORT;thread_args = (zbx_thread_args_t *)zbx_malloc(NULL, sizeof(zbx_thread_args_t));thread_args->thread_num = thread_num;thread_args->args = &activechk_args;threads[thread_num++] = zbx_thread_start(active_checks_thread, thread_args);}

其中collector_thread会每隔1s收集本机的cpu状态存入结构体ZBX_CPUS_STAT_DATA中，将磁盘的状态存入结构体ZBX_DISKDEVICES_DATA

typedef struct{zbx_uint64_th_counter[ZBX_CPU_STATE_COUNT][MAX_COLLECTOR_HISTORY];unsigned charh_status[MAX_COLLECTOR_HISTORY];inth_first;inth_count;intcpu_num;}ZBX_SINGLE_CPU_STAT_DATA;typedef struct{ZBX_SINGLE_CPU_STAT_DATA*cpu;intcount;}ZBX_CPUS_STAT_DATA;

 

typedef struct c_single_diskdevice_data{charname[32];intindex;time_tclock[MAX_COLLECTOR_HISTORY];zbx_uint64_tr_sect[MAX_COLLECTOR_HISTORY];zbx_uint64_tr_oper[MAX_COLLECTOR_HISTORY];zbx_uint64_tr_byte[MAX_COLLECTOR_HISTORY];zbx_uint64_tw_sect[MAX_COLLECTOR_HISTORY];zbx_uint64_tw_oper[MAX_COLLECTOR_HISTORY];zbx_uint64_tw_byte[MAX_COLLECTOR_HISTORY];doubler_sps[ZBX_AVG_COUNT];doubler_ops[ZBX_AVG_COUNT];doubler_bps[ZBX_AVG_COUNT];doublew_sps[ZBX_AVG_COUNT];doublew_ops[ZBX_AVG_COUNT];doublew_bps[ZBX_AVG_COUNT];} ZBX_SINGLE_DISKDEVICE_DATA;typedef struct c_diskdevices_data{intcount;ZBX_SINGLE_DISKDEVICE_DATAdevice[MAX_DISKDEVICES];} ZBX_DISKDEVICES_DATA;

zabbix_agent和zabbix_server通信有两种方式：主动和被动，即它可以主动的发送信息给zabbix_server，也可以等zabbix_server请求时在发送相关的信息进行响应。默认情况这两个方式都开启了。另外，zabbix_server和zabbix_agent通信的协议是json格式的，详细格式请查阅官网文档。

    listener_thread进程是负责被动方式，它负责监听10050端口，然后等待server端的请求并进行响应，请看下面的代码（listener.c）

static voidprocess_listener(zbx_sock_t *s){AGENT_RESULTresult;char*command;char**value = NULL;intret;if (SUCCEED == (ret = zbx_tcp_recv_to(s, &command, CONFIG_TIMEOUT))){zbx_rtrim(command, "\r\n");zabbix_log(LOG_LEVEL_DEBUG, "Requested [%s]", command);init_result(&result);process(command, 0, &result);if (NULL == (value = GET_TEXT_RESULT(&result)))value = GET_MSG_RESULT(&result);if (NULL != value){zabbix_log(LOG_LEVEL_DEBUG, "Sending back [%s]", *value);ret = zbx_tcp_send_to(s, *value, CONFIG_TIMEOUT);}free_result(&result);}if (FAIL == ret)zabbix_log(LOG_LEVEL_DEBUG, "Process listener error: %s", zbx_tcp_strerror());}

值得一提的是从服务器接收的变量command，它其实就是我们在前台页面添加item时填的key，接下来有这么一个结构

ZBX_METRICparameters_common[] =/*      KEY                     FLAGFUNCTION        ADD_PARAM       TEST_PARAM */{{"agent.ping",0,AGENT_PING, 0,0},{"agent.version",0,AGENT_VERSION,0,0},{"system.localtime",0,SYSTEM_LOCALTIME,0,0},{"system.run",CF_USEUPARAM,SYSTEM_RUN, 0,"echo test"},{"web.page.get",CF_USEUPARAM,WEB_PAGE_GET, 0,"localhost,,80"},{"web.page.perf",CF_USEUPARAM,WEB_PAGE_PERF, 0,"localhost,,80"},{"web.page.regexp",CF_USEUPARAM,WEB_PAGE_REGEXP,0,"localhost,,80,OK"},｝

这个结构体将key和agent接收到key后执行的function联系到了一起

    active_checks_thread进程是负责主动发送收集到的信息给zabbix_server的。除此之外，他还负责发送心跳包已经更新自己维护的一个active_checks条目表，部分代码（active.c：ZBX_THREAD_ENTRY(active_checks_thread, args)）如下：

while (ZBX_IS_RUNNING()){if (time(NULL) >= nextsend){send_buffer(activechk_args.host, activechk_args.port); //负责发送心跳包nextsend = (int)time(NULL) + 1;}if (time(NULL) >= nextrefresh){zbx_setproctitle("poller [getting list of active checks]");if (FAIL == refresh_active_checks(activechk_args.host, activechk_args.port))  //更新自己维护的一个active_checks条目表{nextrefresh = (int)time(NULL) + 60;}else{nextrefresh = (int)time(NULL) + CONFIG_REFRESH_ACTIVE_CHECKS;}}if (time(NULL) >= nextcheck && CONFIG_BUFFER_SIZE / 2 > buffer.pcount){zbx_setproctitle("poller [processing active checks]");process_active_checks(activechk_args.host, activechk_args.port); //主动发送收集到的信息给zabbix_serverif (CONFIG_BUFFER_SIZE / 2 <= buffer.pcount) /* failed to complete processing active checks */continue;nextcheck = get_min_nextcheck();if (FAIL == nextcheck)nextcheck = (int)time(NULL) + 60;}else{zabbix_log(LOG_LEVEL_DEBUG, "Sleeping for %d second(s)", 1);zbx_setproctitle("poller [sleeping for %d second(s)]", 1);zbx_sleep(1);}}

 转载请注明出处：http://blog.csdn.net/liujian0616/article/details/7932323