Generated NRPE checks swallow quotes

[Haw Loeung]

Hi,

The graylog charm has this bit of code:

| if conf['web_listen_uri']:
| url = urlparse(conf['web_listen_uri'])
| check_string = '<title>Graylog Web Interface</title>'
| nrpe_setup.add_check(
| 'graylog_http',
| 'Graylog Web UI check',
| '/usr/lib/nagios/plugins/check_http -I {} -p {} -s "{}"'.format(url.hostname, str(url.port), check_string)

Which is supposed to generate a check such as this:

| command[check_graylog_http]=/usr/lib/nagios/plugins/check_http -I 0.0.0.0 -p 9000 -s "<title>Graylog Web Interface</title>"

Unfortunately, the double-quote characters are being stripped and the generated check is actually this:

| $ cat /etc/nagios/nrpe.d/check_graylog_http.cfg
| # check graylog_http
| # The following header was added automatically by juju
| # Modifying it will affect nagios monitoring and alerting
| # servicegroups: is-centralized-logging
| command[check_graylog_http]=/usr/lib/nagios/plugins/check_http -I 0.0.0.0 -p 9000 -s <title>Graylog Web Interface</title>

Which then causes the check to fail.

I think it may be the use of **kwargs, but I'm not sure.

[Paul Collins (pjdc)]

I think it's because Check.__init__ does this:

        parts = shlex.split(check_cmd)

and then does this:

                    command += " " + " ".join(parts[1:])

instead of using shlex.join.

[Paul Collins (pjdc)]

https://github.com/juju/charm-helpers/pull/438

[Paul Collins (pjdc)]

PR won't work as-is, since shlex.quote is very new.

[Paul Collins (pjdc)]

Updated PR with adapted copy of shlex.quote etc. from Python 3.8 to use as a fallback.

[Paul Collins (pjdc)]

I realized the approach in the PR above will break the existing escaping workarounds used in all such add_check calls, so I've closed the PR while I try to think of a better idea.