On Wednesday, January 21, 2015 at 4:24:19 PM UTC-6, omfg9899 wrote:
>
> Hello all and thanx in advance to anyone that replies to my endless
> headache here.
>
> I am trying to do a couple of things, and failing miserably. I will
> touch on the most important one for the moment.
>
> I am trying to set a variable based on a variable. Effectively a dynamic
> variable. I can do this in bash all day long. :/
>
> class webapps_dt($envir = "${which_envir}", $envir = upcase($envir),
> $agent_name = "WEBAPP_EC2EAST_$envir_SERVICE, $server = "
> collector-somehost.atsome-domain.com", $version="5.5.0") {
>
>
> The problem is, I can't figure out for the life of me how to nest or
> embed that variable inside that variable. I can nest or embed a fact, but
> not another variable. In case anyone is wondering, the second thing I am
> trying to solve is upper casing the original fact. What I am searching for
> is the environment in which the machines are built. ( dev / cert / prod ),
> but I want them to be uppercase like the rest of the string. That has of
> course failed too. So assuming that envir = DEV, I can't get this to work..
>
>
You cannot specify the same parameter name twice in one class's
declaration. It simply doesn't make sense -- they conflict.
You also cannot interpolate a class parameter's value into *its own*
default value. This stands to reason because the default is relevant only
when no value is specified for the parameter. Moreover, you cannot modify
a class parameter's (or any other Puppet variable's) value once it is
assigned. You can, however, create a separate class variable that contains
the transformed value you want.
As a separate matter, you cannot reliably interpolate the value of one
class parameter into the default value of a different one, though there is an
outstanding feature request for that
<https://tickets.puppetlabs.com/browse/PUP-1080>. In practice, doing so
works for some combinations of parameters but not for others, and it is
difficult to predict which will and won't work. You have a few options
here, among them:
(1) Similar to the case of transforming a parameter value, you can create a
separate class variable (not parameter) in which to assemble the wanted
value. Example:
class webapps_dt($envir = "${which_envir}", $agent_name = undef) {
$envir_upcase = upcase($envir)
if $agent_name {
$agent_name_real = $agent_name
} else {
$agent_name_real = "WEBAPP_EC2EAST_${envir_upcase}_SERVICE"
}
# ... use $agent_name_real
}
(Note the braces around the variable name in the interpolation, by the
way. Since you are proficient with bash scripting, I don't need to
explain.)
(2) You can create a wrapper class that performs the data munging you want,
and declares the true target class with the right parameters. The easiest
way to do this is just a special case of (1), though, so it's usefulness is
limited. It mainly serves cases where *other* classes, not themselves
declared by the target class, rely on the values of the target class's
parameters:
class webapps_dt_wrapper($envir = "${which_envir}", $agent_name = undef) {
$envir_upcase = upcase($envir)
if $agent_name {
$agent_name_real = $agent_name
} else {
$agent_name_real = "WEBAPP_EC2EAST_${envir_upcase}_SERVICE"
}
class { 'webapps_dt':
envir => $envir,
agent_name => $agent_name_real
}
}
John
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