如何在一个hos上运行@rolesdecorated fabric任务

Question

我有一个用@roles修饰的任务，我偶尔想在单个主机上运行（对于canary测试部署）。在

from fabric.api import *

env.roledefs = {
    'web-workers': ['django@worker1', 'django@worker2'],
    'some-other-role': ['django@worker2'],
}

@task
@roles('web-workers')
def bogomips():
    run('uptime')

docs for ^{}声明：

...barring an override on the command line, my_func will be executed against the hosts listed [in the role]...

但是我不能让这里提到的“覆盖”功能工作。。。我试过：

^{pr2}$

但它总是在decorator中提到的整个角色上执行。。。在

我错过了什么？如何覆盖@roles修饰任务的运行位置？在

Answer 1

根据Execution model's Order of Precedence，这实际上是预期的行为，在这个场景中必须使用稍微不同的语法。在

下面是一个不起作用的命令：

$ fab bogomips -R some-other-role # fabric ignores the -R values!

这个版本就是这样的：

^{pr2}$

问题是：#308: @roles and @hosts decorators ignore command line options

还有文件：http://docs.fabfile.org/en/1.0.0/usage/execution.html#order-of-precedence

• Per-task, command-line host lists (fab mytask:host=host1) override absolutely everything else.
• Per-task, decorator-specified host lists (@hosts('host1')) override the env variables.
• Globally specified host lists set in the fabfile (env.hosts = ['host1']) can override such lists set on the command-line, but only if you’re not careful (or want them to.)
• Globally specified host lists set on the command-line ( hosts=host1) will initialize the env variables, but that’s it.