The line

    my $json = quotemeta( {"auth":{"RAX-KSKEY:apiKeyCredentials":{"use
+rname":$USERNAME, "apiKey":$API_KEY}}} );
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The Perl equivalent of a JSON map is called a hash. Traditionally we use => to separate keys from their values, not :.

    my $json = quotemeta( {"auth" => {"RAX-KSKEY:apiKeyCredentials" =>
+ {"username" => $USERNAME, "apiKey" => $API_KEY}}} );
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But even that would make little sense. That line would make the data structure, return a reference to it, try to quotemeta that reference, and store that in $json. So $json would end up being something like "HASH\(0x33c218\)". You don't need quotemeta here — you only need quotemeta when you're about to use a string inside a regular expressions and you're afraid that your string might have regex meta characters while you actually want to match them literally. What you do need is a real JSON module, like the good monks before me already suggested.