Firehose support for tag_update API

[dpajin-kentik]

What are you trying to achieve?

In order to decode custom dimensions we must feed firehose with a local .csv file which it can use to map internal column numbers to human readable columns for raw kflow export. This is a manual process to extract the list of custom dimensions for a particular CID, and apply that to the firehose process on launch.

If a new custom dimension is added, a user would need to recognize this, extract the new column mapping, modify the tag file and HUP the firehose process to pick up the new mapping.

Ideally we would expose an API endpoint which the firehose process could query to periodically obtain updated mappings which it would retrieve and automatically update without any user interaction. This functionality should be able to leverage the existing -e KENTIKAPITOKEN and -kentik_email flags to authenticate.

What is your current work around?

manually extract the mapping list, export to .csv and provide that file to users running firehose with Custom Dimensions

cc @kentik-rbarnes