Cloudflare dynamic DNS and booleans

Cloudflare have an API that allows DNS records to be updated — assuming you use Cloudflare to manage your DNS records.

If not, look away now.

Using curl you make a PUT request to a particular URL, supplying authentication details in the form of an email and the API key. There are further details online; for example, here.

Part of the request is submitted in JSON format. Not a problem except for the need to submit a boolean true value for one of the records. This turned out to be more problematic than I expected using Perl.

I use the JSON::Tiny module to convert a hash (key-value pairs) of data into JSON format to append to the PUT request. Any variant of 'true', escaped or not, caused Cloudflare to 'barf' and reject the dynamic DNS update.

And the answer is …

Use \1 as the value, which (together with \0) is a scalar reference, that indicates boolean true (and, for \0 … false, obviously).

So you start with a hash that looks something like this (some authentication bits removed for security):

my %json = (
  content => $ip,
  name    => 'geekery.theapiarist.org',
  proxied => \1,
  type    => 'A',
  comment => $comment,
  tags    => [],
  ttl     => 3600,
);

which, when dealt with by encode_json, returns:

{"comment":"Updated","content":"123.456.789.123","name":"geekery.theapiarist.org","proxied":true,"tags":[],"ttl":3600,"type":"A"}

Note the absence of quoting on the proxied entry.

Simple when you know how, which I didn't 😞, which is why it took me an hour and some Google-fu to find the answer.

#perl
#cloudflare