On Friday, August 2, 2013 6:43:01 AM UTC-7, jcbollinger wrote:
>
>
>
> On Thursday, August 1, 2013 2:37:03 PM UTC-5, Jacob McCoy Wade wrote:
>>
>> The closest I've come is to use:
>>
>>> $random_1 = generate('/bin/sh', '-c', '\"/bin/cat /dev/urandom | /usr
>>> /bin/tr -dc \'a-z0-9\' | /usr/bin/fold -w 8 | /usr/bin/head -n 1 | /usr
>>> /bin/tr -d \'\n\'\"')
>>
>>
>> This however ends up populating the variable with the following and
>> appears to ignore the the "/usr/bin/tr -d '\n'" as there are line breaks
>> inserted:
>>
>>> /bin/sh: "/bin/cat: No such file or directory
>>>
>>
>>
> So, that's the wrong thing to do, because 'cat' will keep reading its
> input until it reaches the end, which it never will in this case. It may
> be that having 'head' in the pipeline would rescue it by closing its own
> input, but you might end up with a bunch of stalled, orphaned processes.
> You should instead use /bin/dd or some other command that allows you to
> limit the amount of data read from /dev/urandom.
>
> I was using head to close the input. The other thing I can't quite make
sense of is why it works when I apply the module directly on the node, but
not when using a puppet master.
> There is also a third, more fundamental problem: it is unlikely that you
> really want to do what you are trying to do. If you generate a completely
> random component to a config file on every run, then that file will never
> match from one run to the next, so it will always be re-synced. That is
> rarely the intent. More often, you want different, random strings for each
> node, but you want those strings to be stable from run to run for any given
> node. One way to achieve that might be to construct strings as the
> concatenation of a constant stem and a random number generated via Puppet's
> built-in fqdn_rand() function.
>
> I was thinking that I could use "replace => 'no'," within the module so
that puppet won't re-sync the file every run.
> Even if that would not be sufficient, I have trouble seeing why it makes
> sense to use generate() for this purpose. It would be not only
> lighter-weight but also more flexible to use Ruby's rand() function via
> Puppet's inline_template() function. You could even use fqdn_rand() to
> seed the Ruby RNG, so as to get a broader range of consistent pseudorandom
> values. And, you would have as much control as you want over the random
> data -- such as, for instance, ensuring that it does not contain null (0)
> bytes.
>
> I've yet to use the inline_template() function and am not fluent enough in
Ruby to know how to use the rand() function, but it sounds like it might be
time to learn how :)
> As for the question in your title, to insert the literal two-character
> sequence '\n' into a double-quoted Puppet string, escape the backslash by
> doubling it: "... /usr/bin/tr -d '\\n'". (See
> http://docs.puppetlabs.com/puppet/3/reference/lang_datatypes.html#strings.)
> Note that only the outermost quotes affect what escape sequences are
> recognized; the inner single quotes in your string are just ordinary
> characters to Puppet.
>
That helps me at least understand about escape sequencing in Puppet. The
other issue with using the generate() function is that I run in to either
"Generators must be fully qualified" or "Generators can only contain
alphanumerics, file separators, and dashes". More proof that it's time to
give up on trying to make the generator() function work for this purpose.
Thanks for the help.
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