Python 实时获取任务请求对应的Nginx日志

需求描述

项目需求测试过程中，需要向Nginx服务器发送一些用例请求，然后查看对应的Nginx日志，判断是否存在特征内容，来判断任务是否执行成功。为了提升效率，需要将这一过程实现自动化。

实践环境

Python 3.6.5

代码设计与实现

#!/usr/bin/env python
# -*- coding:utf-8 -*-


"""
@CreateTime: 2021/06/26 9:05
@Author : shouke
"""


import time
import threading
import subprocess
from collections import deque


def collect_nginx_log():
    global nginx_log_queue
    global is_tasks_compete
    global task_status


    args = "tail -0f /usr/local/openresty/nginx/logs/access.log"
    while task_status != "req_log_got":
        with subprocess.Popen(args, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True, universal_newlines = True) as proc:
            log_for_req = ""
            outs, errs = "", ""

            try:
                outs, errs = proc.communicate(timeout=2)
            except subprocess.TimeoutExpired:
                print("获取nginx日志超时，正在重试")
                proc.kill()
                try:
                    outs, errs = proc.communicate(timeout=5)
                except subprocess.TimeoutExpired:
                    print("获取nginx日志超时，再次超时，停止重试")
                    break
            finally:
                for line in outs.split("
"):
                    flag = ""client_ip":"10.118.0.77"" # 特征
                    if flag in line: # 查找包含特征内容的日志
                        log_for_req += line

                if task_status == "req_finished":
                    nginx_log_queue.append(log_for_req)
                    task_status = "req_log_got"



def run_tasks(task_list):
    """
    运行任务
    :param task_list 任务列表
    """

    global nginx_log_queue
    global is_tasks_compete
    global task_status


    for task in task_list:
        thread = threading.Thread(target=collect_nginx_log,
                                    name="collect_nginx_log")
        thread.start()
        time.sleep(1) # 执行任务前，让收集日志线程先做好准备

        print("正在执行任务：%s" % task.get("name"))

        # 执行Nginx任务请求
        # ...

        task_status = "req_finished"
        time_to_wait = 0.1
        while task_status != "req_log_got": # 请求触发的nginx日志收集未完成
            time.sleep(time_to_wait)
            time_to_wait += 0.01
        else:# 获取到用例请求触发的nginx日志
            if nginx_log_queue:
                nginx_log = nginx_log_queue.popleft()
                task_status = "req_ready"
                # 解析日志
                # do something here
                # ...
            else:
                print("存储请求日志的队列为空")
                # do something here
                # ...


if __name__ == "__main__":
    nginx_log_queue = deque()
    is_tasks_compete = False # 所有任务是否执行完成

    task_status = "req_ready" # req_ready，req_finished，req_log_got  # 存放执行次任务任务的一些状态
    print("###########################任务开始###########################")

    tast_list = [{"name":"test_task", "other":"..."}]
    run_tasks(tast_list)

    is_tasks_compete = True

    current_active_thread_num = len(threading.enumerate())
    while current_active_thread_num != 1:
        time.sleep(2)
        current_active_thread_num = len(threading.enumerate())
    print("###########################任务完成###########################")

注意：

1、上述代码为啥不一步到位，直接 tail -0f /usr/local/openresty/nginx/logs/access.log | grep "特征内容"呢？这是因为这样做无法获取到Nginx的日志

2、实践时发现，第一次执行proc.communicate(timeout=2)获取日志时，总是无法获取，会超时，需要二次获取，并且timeout设置太小时(实践时尝试过设置为1秒)，也会导致第二次执行时无法获取Nginx日志。