The tag endpoint allows you to assign tags to hosts,
role:database. Those tags are applied to
all metrics sent by the host. Refer to hosts by name
yourhost.example.com) when fetching and applying
tags to a particular host.
The component of your infrastructure responsible for a tag is identified
by a source. For example, some valid sources include nagios, hudson, jenkins,
users, feed, chef, puppet, git, bitbucket, fabric, capistrano, etc.
Read more about tags on the dedicated