python - 如何将参数传递给 python fabric 自定义任务

Question

我不知道如何实际将参数传递给结构自定义任务。

我有一堆任务都需要做相同的设置，所以我希望将任务子类化并让基类进行设置，然后运行特定的子任务。设置代码和子任务都需要访问从命令行传递给任务的一些参数。我还需要能够为参数设置默认值。

最初的尝试

我最初的尝试展示了我在没有任何子类的情况下尝试做的事情。此代码工作正常。下面的代码在文件 tmp1.py 中:

from fabric.api import task

def do_setup(myarg):
    ''' common setup for all tasks '''
    print "in do_setup(myarg=%s)" % myarg
    # do setup using myarg for something important

@task
def actual_task1(myarg='default_value', alias='at'):
    print "In actual_task1(myarg=%s)" % myarg
    do_setup(myarg)
    # do rest of work ...

@task
def actual_task2(myarg='default_value', alias='at'):
    print "In actual_task2(myarg=%s)" % myarg
    do_setup(myarg)
    # do rest of work ...

我在没有任何参数的情况下从命令行运行它，并正确地看到 myarg 的默认值“default_value”

fab -f ./tmp1.py actual_task1

打印:

In actual_task1(myarg=default_value)
in do_setup(myarg=default_value)
Done.

然后我用 myarg='hello' 调用它并看到 'hello' 被正确传递

fab -f ./tmp1.py actual_task1:myarg='hello'

输出:

In actual_task1(myarg=hello)
in do_setup(myarg=hello)
Done.

尝试自定义任务

我的下一个尝试是做一个通用任务来封装设置部分。这是从http://docs.fabfile.org/en/1.5/usage/tasks.html复制的下面的代码在文件 tmp2.py 中:

from fabric.api import task
from fabric.tasks import Task

def do_setup(myarg):
    ''' common setup for all tasks '''
    print "in do_setup(myarg=%s)" % myarg
    # do setup using myarg for something important

'''
Attempt to make a common task to encapsulate the setup part
copied from http://docs.fabfile.org/en/1.5/usage/tasks.html
'''
class CustomTask(Task):
    def init(self, func, myarg, args, *kwargs):
        super(CustomTask, self).init(args, *kwargs)
        print("=> init(myarg=%s, args=%s, kwargs=%s" % (myarg, args, kwargs))
        self.func = func
        self.myarg = myarg
        print "in init: self.func=",self.func,"self.myarg=",self.myarg

    def run(self, *args, **kwargs):
        return self.func(self.myarg, *args, **kwargs)

@task(task_class=CustomTask, myarg='default_value', alias='at')
def actual_task1():
    print "In actual_task1(myarg=%s)" % myarg
    # do rest of work ...

运行时，有2个问题:

1. __init__ 获取“default_value”而不是“Hello”

2. 它提示 actual_task1() 需要 0 个参数

我是这样运行的:

fab -f ./tmp2.py actual_task1:myarg="Hello"

打印:

=> init(myarg=default_value, args=(), kwargs={'alias': 'at'}
in init: self.func= self.myarg= default_value
Traceback (most recent call last):
File "/home/xxx/Documents/pyenvs/xxx/local/lib/python2.7/site-packages/fabric/main.py", line 743,      in main args, *kwargs
File "/home/xxx/Documents/pyenvs/xxx/local/lib/python2.7/site-packages/fabric/tasks.py", line 405,  in execute results[''] = task.run(args, *new_kwargs)
File "/home/xxx/test_fab/tmp2.py", line 21, in run
return self.func(self.myarg, args, *kwargs)
TypeError: actual_task1() takes no arguments (1 given)

我花了很多时间来尝试完成这项工作，但我似乎无法解决 default_value 问题。我肯定错过了什么？

如果您能帮助我弄清楚如何运行此示例程序，我将不胜感激。具有自定义任务的第二个版本需要像我展示的原始版本一样运行。

感谢您对此问题的帮助。

Answer 1

带有设置的固定示例:

from fabric.api import task
from fabric.tasks import Task

def do_setup(foo, verbose):
    ''' common setup for all tasks '''
    print "IN do_setup(foo=%s, verbose=%s)" % (foo, verbose)
    # do setup using foo and verbose...

class CustomTask(Task):
    def __init__(self, func, *args, **kwargs):
        ''' 
        The special args like hosts and roles do not show up in
        args, and kwargs, they are stripped already.

        args and kwargs may contain task specific special arguments
        (e.g. aliases, alias, default, and name) to customize the
        task. They are set in the @task decorator and cannot be passed
        on the command-line. Note also that these special task
        arguments are not passed to the run method.

        Non-special arguments (there are none in this example) are
        set in the task decorator. These other arguments are not
        passed to the run method and cannot be overridden from the
        command-line.

        Note that if you pass any "task specific special arguments" or
        "non-special arguments declared in the task decorator" from the
        command-line, they are treated as different arguments and the
        command-line values are passed to the run method but not to
        this method.
        '''
        super(CustomTask, self).__init__(*args, **kwargs)
        print "IN __init__(args=%s, kwargs=%s)" % (args, kwargs)
        self.func = func

    def run(self, foo='foo_default_val', verbose='verbose_default_val', 
            *args, **kwargs):
        ''' 
        The arguments to this method will be:
        1) arguments from the actual task (e.g. foo and verbose). This method
        is where you set a default value for the arguments from the
        actual_task, not on the actual_task.
        2) task specific arguments from the command-line
        (e.g. actual_task:bar='xxx'). This example is not expecting any,
        so it strips them and does not pass them to the
        actual_function one (e.g. it calls self.func with only foo
        and verbose and does not pass args and kwargs)
        '''
        print "IN run(foo=%s, verbose=%s, args=%s, kwargs=%s)" % \
                  (foo, verbose, args, kwargs)
        do_setup(foo, verbose)
        return self.func(foo, verbose)

@task(task_class=CustomTask, alias="RUNME")
def actual_task(foo, verbose):
    print 'IN task actual_task(foo=%s, verbose=%s)' % (foo, verbose)

仅使用命令行中指定的主机运行:

fab -f ./example_with_setup.py actual_task:host='hhh'

IN __init__(args=(), kwargs={'alias': 'RUNME'})
[hhh] Executing task 'actual_task'
IN run(foo=foo_default_val, verbose=verbose_default_val, args=(), kwargs={})
IN do_setup(foo=foo_default_val, verbose=verbose_default_val)
IN task actual_task(foo=foo_default_val, verbose=verbose_default_val)

在命令行上指定 foo 运行:

fab -f ./example_with_setup.py actual_task:host='hhh',foo='bar'

IN __init__(args=(), kwargs={'alias': 'RUNME'})
[hhh] Executing task 'actual_task'
IN run(foo=bar, verbose=verbose_default_val, args=(), kwargs={})
IN do_setup(foo=bar, verbose=verbose_default_val)
IN task actual_task(foo=bar, verbose=verbose_default_val)

在命令行上同时指定 foo 和 verbose 运行:

fab -f ./example_with_setup.py actual_task:host='hhh',foo='bar',verbose=True

IN __init__(args=(), kwargs={'alias': 'RUNME'})
[hhh] Executing task 'actual_task'
IN run(foo=bar, verbose=True, args=(), kwargs={})
IN do_setup(foo=bar, verbose=True)
IN task actual_task(foo=bar, verbose=True)