Grafana: select host for a dashboard
InfluxDB is running on a Raspberry Pi in my home network (with separate attached disk), and I installed a Grafana on top of it, to visualize crucial data.
In Grafana it is possible to define a variable for a dashboard and this variable can query the data source and use the returned list of values. Let's say the variable is $host, then the data query can use:
WHERE host =~ /^$host$/
and limit the current dashboard to the selected host. Also the variable will provide a select field at the top of the dashboard, which allows selecting the system one wants to see:
Now usually - according to the documentation - a "SHOW TAG VALUES" in the data source should be sufficient However as it is, this did not work for me, and the query came back empty:
> show tag values from system with key = host
Looks like I'm not the only one with this problem.
Luckily there is a way around with another query:
select distinct("host") from (select "host","load1" from system)
> select distinct("host") from (select "host","load1" from system) name: system time distinct ---- -------- 0 host1 0 host2 0 host3 0 host4 0 host5 0 host6
Grafana ignores the "time" column and uses the second column for the host list. Voila.