Re: [Fab-user] with_settings decorator generating RuntimeError (generator didn't yield)

[Brandon Whaley]

Hi Felix,

You're not the first to hit this problem.  When I've tested in the
past, it seems like the decorator code is getting executed more than
once, but since it relies on generators, that means the second time
fails.  I haven't yet figured out why that happens but I may take some
time this weekend to come up with a minimal test case and go from
there.

On Thu, Mar 12, 2015 at 10:20 AM, Felix Almeida
<address@hidden> wrote:
> Hi Carlos,
>
>
>
>   Yes, if I do that it works (in fact that’s how it was before):
>
>
>
> def _my_function():
>
>     with settings(hide("status")):
>
>         try:
>
>             out = run("uname")
>
>             puts("OS is " + out)
>
>         except SystemExit:
>
>             puts("can't get the OS")
>
>
>
>   However having to indent the whole function body just because I want to
> hide the status messages is weird, especially after reading this:
>
>
>
> “Allows you to wrap an entire function as if it was called inside a block
> with the settings context manager. This may be useful if you know you want a
> given setting applied to an entire function body...” (source:
> http://docs.fabfile.org/en/latest/api/core/decorators.html#fabric.decorators.with_settings).
>
>
>
>   Which is exactly what I want.
>
>
>
>   Anyway, maybe I should just do that and move on, but it’s kind of
> frustrating.
>
>   Moreover, now I’m curious about why this error is happening and I’m sure
> there is a learning opportunity there for me. ;)
>
>
>
> Thanks,
>
> Felix
>
>
>
>
>
> From: Carlos García [mailto:address@hidden
> Sent: Thursday, March 12, 2015 5:04 AM
> To: Felix Almeida
> Cc: address@hidden
> Subject: Re: [Fab-user] with_settings decorator generating RuntimeError
> (generator didn't yield)
>
>
>
> Hi Felix,
>
>
>
> Have you try to use a context manager instead of the decorator? I´m not
> really sure if you can use it as a decorator...
>
>
>
>
>
> def _my_function():
>
>   with_settings(hide("status")):
>
>     try:
>
>         out = run("uname")
>
>         puts("OS is " + out)
>
>     except SystemExit:
>
>         puts("can't get the OS")
>
>
>
> That's the way I'm using it in my scripts and it seems to work, but we're
> using it just for Ubuntu and CentOS...
>
>
>
> Keep us posted
>
>
>
> Regards!
>
>
>
> 2015-03-12 0:53 GMT+01:00 Felix Almeida <address@hidden>:
>
> Hi all,
>
>
>
>   I need to validate if a certain UNIX account is able to log in to a series
> of servers of mixed flavors (HP-UX, Solaris, RHEL and AIX) so I’m trying to
> do it with fabric.
>
>
>
>   I wanted to apply hide("status") to an entire internal function, but I
> keep getting the following error:
>
>
>
> elxin009: ~/fabric # fab main
>
> [bsnbk001] out: SunOS
>
> [bsnbk001] out:
>
> [bsnbk001] OS is SunOS
>
> Disconnecting from bsnbk001... done.
>
> Traceback (most recent call last):
>
>   File "/usr/local/lib/python2.7/site-packages/fabric/main.py", line 743, in
> main
>
>     *args, **kwargs
>
>   File "/usr/local/lib/python2.7/site-packages/fabric/tasks.py", line 424,
> in execute
>
>     results['<local-only>'] = task.run(*args, **new_kwargs)
>
>   File "/usr/local/lib/python2.7/site-packages/fabric/tasks.py", line 174,
> in run
>
>     return self.wrapped(*args, **kwargs)
>
>   File "/home/felix/fabric/fabfile.py", line 24, in main
>
>     execute(_my_function, hosts=host_list)
>
>   File "/usr/local/lib/python2.7/site-packages/fabric/tasks.py", line 384,
> in execute
>
>     multiprocessing
>
>   File "/usr/local/lib/python2.7/site-packages/fabric/tasks.py", line 274,
> in _execute
>
>     return task.run(*args, **kwargs)
>
>   File "/usr/local/lib/python2.7/site-packages/fabric/tasks.py", line 174,
> in run
>
>     return self.wrapped(*args, **kwargs)
>
>   File "/usr/local/lib/python2.7/site-packages/fabric/decorators.py", line
> 215, in inner
>
>     with settings(*arg_settings, **kw_settings):
>
>   File "/usr/local/lib/python2.7/contextlib.py", line 17, in __enter__
>
>     return self.gen.next()
>
>   File "/usr/local/lib/python2.7/contextlib.py", line 112, in nested
>
>     vars.append(enter())
>
>   File "/usr/local/lib/python2.7/contextlib.py", line 19, in __enter__
>
>     raise RuntimeError("generator didn't yield")
>
> RuntimeError: generator didn't yield
>
>
>
>   This is a very simplified version of my original code that I’m using for
> troubleshooting since it generates the same error:
>
>
>
> from fabric.api import task, hide, execute, env, puts, run, with_settings
>
>
>
> env.use_shell = False
>
> env.disable_known_hosts = True
>
> env.warn_only = True
>
> env.abort_on_prompts = True
>
> env.skip_bad_hosts = True
>
> env.command_timeout = 3
>
> env.eagerly_disconnect = True
>
> env.always_use_pty = False
>
>
>
> @with_settings(hide("status"))
>
> def _my_function():
>
>     try:
>
>         out = run("uname")
>
>         puts("OS is " + out)
>
>     except SystemExit:
>
>         puts("can't get the OS")
>
>
>
> @task
>
> def main():
>
>     host_list = [line.rstrip("\n") for line in open("hosts.txt")]
>
>     with hide("running"):
>
>         execute(_my_function, hosts=host_list)
>
>
>
>   The hosts.txt file is just a text file with one hostname per line. This
> was the content of the file when I captured the output above (just two
> servers):
>
>
>
> bsnbk001
>
> slxap003
>
>
>
>   In fact, none of the env settings makes any difference, but if I comment
> out the @with_settings line it works as expected. If the hosts.txt file
> contains only one hostname then it also works without any errors.
>
>
>
>   Please, any ideas of what I am doing wrong? I’m still learning Python so
> forgive me if I’m doing something silly.
>
>
>
>
>
> Thank you,
>
> Felix
>
>
>
> PS: I’m running Fabric 1.10.1 and Paramiko 1.15.2 on RHEL.
>
>
>
>
>
>
>
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