fabtools.postgres.user_exists() quick fix about fabtools HOT 14 CLOSED

I use the root user to connect via SSH.

fab check_user
Executing task 'check_user'
res: 'could not change directory to "/root"\r\n1'
True

Done.

the check_user task is a call to pg_user_exists(username), it's my modified function of postgres.user_exists(username)

def pg_user_exists(name):
    with settings(hide('running', 'stdout', 'stderr', 'warnings'),
        warn_only=True):
        res = _run_as_pg('''psql -t -A -c "SELECT count(*) FROM pg_user WHERE usename='%(name)s';"''' % locals())

    print "res: %r" % (res,)
    return '1' in res

def check_user():
    print pg_user_exists(DATABASE_OWNER)

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Can you reproduce the issue? What is the exact output of the psql command? Maybe you can add a print repr(res) before the return (res == "1") line to understand what happens...

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sure I've done that and reproduced it. printed the command output and the function output side to side.
The output is "1" as expected when the user is already created. But the function still return False, even if you add " echo | psql ..." at the beginning. This is why I was talking about gremlins, or whatever invisble characters mixed in the output.
Whereas ("1" in res) works like a charm for the same situation.

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That's weird.

What version of fabric are you using?

Does return str(res) == "1" work?

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No, it returns "None"

and now (after a vagrant destroy) even my fix does not work
I just got back to the lower level functions

if not fabtools.postgres.user_exists(env.user):
    fabtools.postgres.create_user(env.user, env.pgpass)

And unexpectedly, it works very well (??)

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Problem solved, then? :)

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On va dire que oui...

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Sorry to comment on a closed issue, but this bit me too. I dug a bit, and found the following:

-> return (res == "1")
(Pdb) print res
/bin/bash: /root/.bash_profile: Permission denied
could not change directory to "/root"
1

So - we're getting some error text at the start.

I don't know why this is appearing - it happens on a Ubuntu 10.04 LTS Linode VM, but not a local VMWare one(!). I worked around it by splitting into lines and looking at the last one (see my rough-and-ready fork). It's a weird one.

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Thanks for your comment! This is weird. I'll try to dig into this some more.

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FTR, I still get this on a stock Ubuntu 12.04 LTS, with the latest fabtools. My workaround is to simply chmod a+rx /root - not ideal, but it works, and I don't particularly care if everyone can read /root.

My hunch is that this is happening because the postgres commands run as the 'postgres' user, and this typically doesn't have sudo access; and something, somewhere, is expecting to be able to source root's shell stuff as that user.

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Not sure why it's trying to read /root/.bash_profile... This file does not exist on my Ubuntu VMs. Does it exist on the VMs where you saw the problem?

What's the output of "getent passwd postgres"?

What's the contents of the /etc/sudoers file?

Any other differences between VMs exhibiting the problem and those who don't?

I pushed an attempt at fixing the problem, running commands using "shell=False". Does it work for you?

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You should probably avoid directly connecting as root on your server, and I would even recommend disabling it altogether by adding PermitRootLogin no to /etc/ssh/sshd_config.

I think the problem comes from the fact that, when running a command as another user with sudo, fabric does not change the HOME environment variable, which causes the spurious message in the stdout. Maybe setting the HOME var in _run_as_pg will be able to fix the issue.

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You should probably avoid directly connecting as root on your server, and I would even recommend disabling it altogether by adding PermitRootLogin no to /etc/ssh/sshd_config.

That's true

But it's not a solution. root/sudo shouldn't be encumbered by permission issues

Ended up doing #4 (comment). That is hacky, but in the end, I'm using fabtools for convenience and just getting stuff deployed. I'm not a full-time devops person 😄

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Any elegant solution yet?

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