On Monday, October 28, 2013 11:43:29 AM UTC-5, [email protected] wrote:
>
> Hi,
>
> I am new to Ruby ERB and inline_template. Can anyone spot what's wrong
> with this inline_template?
>
> $moddedContent = inline_template("<%= puts gets(nil).gsub(/one
> two three/,\"\") /tmp/blah %>")
> exec {
> "/bin/echo '${moddedContent}' > /tmp/blah" :
> }
>
> When I try to apply it, I got the following error.
> Error: Could not retrieve catalog from remote server: Error 400 on SERVER:
> Failed to parse inline template: private method `gets' called for
> false:FalseClass at foo.pp:33 on node testnode
>
>
The purpose of an ERB template is to generate strings consisting of zero or
more static parts and one or more dynamic parts. They are otherwise a poor
vehicle for embedding general-purpose Ruby code in your manifests. In
particular, you do not normally want to perform explicit I/O in a
template. You certainly don't want to perform I/O to or from the standard
streams, as these should not be connected/open when the template is
evaluated. It's not clear to me whether the I/O you are doing is your
actual objective (in which case a template is the wrong tool -- use
generate() or a custom function instead) or whether it's just your attempt
at implementing what you're really after.
Also, it is essential to understand that all Puppet DSL functions,
including inline_template(), are executed on the master during catalog
compilation, whereas resources, including Execs, are applied to client
nodes. As such, if a DSL function drops a file on the local file system,
resources cannot normally expected to consume that file because their local
file system at application time is normally a different one.
Here's a trivial example of how an inline template might be used:
$foo = 'one two three four five'
$moddedContent = inline_template("<%= @foo.gsub(/one two three/,'') %>")
notify { 'inline_template demo':
message => "The modified content is $moddedContent"
}
# Yields "The modified content is four five"
Of course, an experienced Puppeteer would never do that particular job via
inline_template(), because the regsubst() function can more clearly,
succinctly, and cheaply express the same thing:
$moddedContent = regsubst($foo, 'one two three', '')
John
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