How to plot horizontal line in Timeseries in Grafana

Question

I use grafana to plot timeseries data. In a timeseries plot i want to add a constant line which comes from a monitoring level. The value of that level is dynamic (from a postgres database) the timeseries come from a ifluxdb Datasource.

The monitoring level have no timestamp. The result should look like this:

I have searched quite a while how to do this, but not found a good explanation.

score 3 · Answer 1 · answered Aug 01 '22 at 12:23

3

You can now add thresholds (bottom of the edit screen).

Each threshold can be represented as a solid line and/or region with individual color

answered Aug 01 '22 at 12:23

Raph

326
3
15

How can you read the thresholds from a datasource? – renzop Jul 04 '23 at 07:55
I don't know if thresholds can be dynamically read from a datasource (I understand that's what you want to do?). At time of writing the above answer all you could do what hard code them if I remember correctly. edit: @HTE seems to have a solution for dynamic threshold – Raph Jul 04 '23 at 21:27

score 3 · Answer 2 · answered Feb 21 '23 at 05:26

It is possible to add dynamic thresholds using the Config from query option.

Add a new query below your standard metric query. This will likely be called B. Here you query the static reference value. Eg SELECT expected_number_of_widgets FROM baseline
Open Transformation tab
Find Configuration from Query results
Choose Config query = B
At the dropdown for expected_number_of_widgets, choose Use as: Threshold1.
In the right panel, under Thresholds, make sure Show Tresholds is enabled and remove the default threshold of 80.

For more details, see https://grafana.com/docs/grafana/latest/panels-visualizations/query-transform-data/transform-data/#config-from-query-results

Good solution, I tried it, but could not make threshold to be visible, though "Show Thresholds" was set to "As lines". — Dmitriy Vinokurov, May 21 '23 at 17:26

renzop · Accepted Answer · 2021-07-20T07:04:12.183

To draw a line like that you have to "fake" a timeseries. (thresholds don't work since they can not be dynamic as far as I know)

First thing to keep in mind is that grafana needs timestamp to plot it, for this reason the global variables ${__to} and ${__from} come in handy.

Then, to draw a line, grafana needs at least two points. ([t0, t1][y0, y1])

So this is the sql (postgre) query that lead to the desired result:

SELECT
  ${__from} AS time,
  level_1,
FROM my_table where display_name = '${my_grafana_var:raw}'
union all
SELECT
  ${__to} AS time,
  level_1,
FROM my_table where display_name = '${my_grafana_var:raw}';

score 1 · Answer 4 · edited Mar 18 '22 at 23:17

Another way to do it in a dirty way is to create panel with a mixed data source. Create your variable in grafana - it can be a query, constant or custom. Just remember to keep it a single floating point. Add your original query and add the prometheus data source to query your variable.

${net_ordered_storage}

You will have to play a little bit with the number of data points displayed (query options>max data points) and minimum step of data point in prometheus query to make grafana connect dots.

Green horizontal line from variable

How to plot horizontal line in Timeseries in Grafana

4 Answers4