混沌工具包不重命名文件

Question

我正在学习混沌工程，我正在学习一个教程，但是我的代码并没有按照它应该运行的方式运行。

我正在测试的服务。

service.py

import io
import time
import threading
from wsgiref.validate import validator
from wsgiref.simple_server import make_server

EXAMPLE_FILE = './example.dat'

def update_file():
    """Write the current time to the file every second."""
    print('Updating file...')
    while True:
        with open(EXAMPLE_FILE, 'w') as f:
            f.write(datetime.now().isoformat())
        time.sleep(1)

def simple_app(environ, start_response):
    """A simple WSGI application.

    This application just writes the current time to the response.
    """
    status = '200 OK'
    headers = [('Content-type', 'text/plain; charset=utf-8')]
    start_response(status, headers)
    with open(EXAMPLE_FILE, 'r') as f:
        return [f.read().encode('utf-8')]

if __name__ == '__main__':
    # Start the file update thread.
    t = threading.Thread(target=update_file)
    t.start()
    httpd = make_server('', 8000, simple_app)
    print("Serving on port 8000...")
    try:
        httpd.serve_forever()
    except KeyboardInterrupt:
        print("\nKeyboard interrupt received, exiting.")
        httpd.shutdown()
        t.join(timeout=1)
        print("Exiting.")

我的混沌实验文件experiment.json

  "title": "Does our service tolerate the loss of its example file?",
  "description": "Our service reads data from a file, can it work without it?",
  "tags": ["tutorial", "filesystem"],

  "steady-state-hypothesis": {
    "title": "The exchange file must exist",
    "probes": [
      {
        "type": "probe",
        "name": "service-is-unavailable",
        "tolerance": [200, 503],
        "provider": {
          "type": "http",
          "url": "http://localhost:8000"
        }
      }
    ]
  },
  "method": [
    {
      "name": "move-example-file",
      "type": "action",
      "provider": {
        "type": "python",
        "module": "os",
        "func": "rename",
        "arguments": {
          "src": "./example.dat",
          "dst": "./example.dat.old"
        }
      }
    }
  ]
}

但是，混沌没有重新命名我的旧文件，而是用提供的名称创建了一个新文件，实验以成功结束，这是我没想到的。

在这里输入图像描述

请帮帮忙。

Answer 1

终于来了！

问题：update_file每秒钟更新一次example.dat文件，如果它不存在，它就会创建它！因此，当chaos将example.dat重命名为example.dat.old时，update_file只是创建了另一个example.dat，似乎一直满足混沌稳态假设。

一种解决方案:将update_file设置为运行时间长得多的时间。在我的例子中，time.sleep(60)起作用了！

来自chaos run experiment.json的日志

[2021-12-07 01:11:19 INFO] Validating the experiment's syntax
[2021-12-07 01:11:19 INFO] Experiment looks valid
[2021-12-07 01:11:19 INFO] Running experiment: Does our service tolerate the loss of its example file?     
[2021-12-07 01:11:19 INFO] Steady-state strategy: default
[2021-12-07 01:11:19 INFO] Rollbacks strategy: default
[2021-12-07 01:11:19 INFO] Steady state hypothesis: The exchange file must exist
[2021-12-07 01:11:19 INFO] Probe: service-is-unavailable
[2021-12-07 01:11:21 INFO] Steady state hypothesis is met!
[2021-12-07 01:11:21 INFO] Playing your experiment's method now...
[2021-12-07 01:11:21 INFO] Action: move-example-file
[2021-12-07 01:11:21 INFO] Steady state hypothesis: The exchange file must exist
[2021-12-07 01:11:21 INFO] Probe: service-is-unavailable
[2021-12-07 01:11:23 CRITICAL] Steady state probe 'service-is-unavailable' is not in the given tolerance so failing this experiment
[2021-12-07 01:11:23 INFO] Experiment ended with status: deviated
[2021-12-07 01:11:23 INFO] The steady-state has deviated, a weakness may have been discovered