Many cloud providers such as Amazon AWS, Digitalocean and Vultr provide an instance metadata service.
Guest instances can discover their own parameters by accessing an API. By convention, this API is accessible from the address 169.254.169.254
To get the value of key 'k', we send an HTTP request to the relative location /$k
If the key corresponds to a tuple, the request is rewritten to key/ which is an index.
If no value or tuple exists, it simply returns not found