Support secondYAxis function

[jkenn99]

Right now the secondYAxis function is ignored

[aalpern]

Hi, could you perhaps provide some more context?

If you're using the graphite renderer, secondYAxis will be interpreted and rendered by Graphite itself, so that should work just fine.

The interactive renderer doesn't know anything about any of the graphite functions that pertain to presentation, rather than data selection, because none of that is in the raw data returned when you ask Graphite for JSON data, rather than a graph. That only exists in the query, and tessera doesn't parse the queries. One of the drawbacks of graphite not separating data and presentation functions.

[jkenn99]

That makes sense. So I'd really be better off making my own extension that can take two queries and render them on two axis?

[aalpern]

For now, yeah, that's probably your best bet.

I wrote a few thoughts on why this is a non-trivial addition in issue #343 (on supporting the equivalent of drawAsInfinite). The options for which data series to associate with each axis need to be set according to the name of the returned data series, which means you have to evaluate the query and keep a map of series names -> display options in the item definition (that's what Grafana does, IIRC).

Supporting any of the per-data-series options in interactive mode will be done by the same chunk of work.