python - Fabric - 测试与多台主机的 SSH 连接

Question

我有一个 Python 脚本，它使用结构库来测试与多个主机的 SSH 连接。我想将所有结果收集在一个列表中:

...
import fabric
from fabric.api import *

results = []

@parallel
def test_connection():
  global results
  try:
    run('ls')
    results += "%s: SUCCESS" % env.host
  except Exception as e:
    results += "%s: FAILURE. Exception: %e" % (env.host, e)

if __name__ == '__main__':
    tasks.execute(test_connection)
    print results

当我执行脚本时，我得到以下信息:

Traceback (most recent call last):
  File "./test_ssh.py", line 99, in <module>
    tasks.execute(test_connection)
  File "/Library/Python/2.7/site-packages/fabric/tasks.py", line 387, in execute
    multiprocessing
  File "/Library/Python/2.7/site-packages/fabric/tasks.py", line 277, in _execute
    return task.run(*args, **kwargs)
  File "/Library/Python/2.7/site-packages/fabric/tasks.py", line 174, in run
    return self.wrapped(*args, **kwargs)
  File "./test_ssh.py", line 96, in test_connection
    results += "%s: FAILURE. Exception: %e" % (env.host, e)
UnboundLocalError: local variable 'results' referenced before assignment

我认为这是因为 test_connection 运行它自己的上下文，所以它无法访问 results。

还有其他方法可以收集我的结果吗？

Answer 1

诀窍在于您实际上可以从并行执行中返回结果:

@parallel
def test_connection():
  try:
    run('ls')
    return True
  except Exception:
    return False

现在当你调用你的任务时，你会得到:

result = execute(test_connection)
results = [ ('HOST %s succeeded' % key) if value else ('HOST %s failed' % key) for key, value in result.items() ]