$__interval template doesn't work

[povilasv]

Currently my change #357 broke dashboards

I tried multiple different ways in grafana UI to fix it, by changing variable template to 'constant', 'text box' type with value $__interval, but it just doesn't render :/

I think there are 2 options:

1. We can get rid of grafana template and "hard code" $__interval into queries

I mean getting rid of this part:

    local intervalTemplate =
      template.new(
        name='interval',
        datasource='$datasource',
        query='$__interval',
        current='5m',
        hide=2,
        refresh=2,
        includeAll=false,
        sort=1
      ) + {
        auto: false,
        auto_count: 30,
        auto_min: '10s',
        skipUrlSync: false,
        type: 'interval',
        options: [
          {
            selected: true,
            text: '$__interval',
            value: '$__interval',
          },
        ],
      },

2. Don't use $__interval

What should we do?

[brancz]

Maybe grafana folks could chime in @beorn7 @gouthamve or maybe @roidelapluie has some insight.

[beorn7]

I'm actually not really a Grafana expert. We could loop in the real experts if needed.

But let's use our own ingenuity first.

My guess is that $__interval doesn't work with template variables. (Perhaps you would need some kind of two layers of variable expansion? But I honestly don't quite understand what you are trying to accomplish here.)

Different question: What's wrong with using $__interval in the queries directly? What are the circumstances where you want to use something else?

[brancz]

I think it was just that we had specific values previously and wanted to avoid creating work for us should we want to switch back again. If there’s nothing then I’m happy with using the variable directly though.

[beorn7]

I see.

I'd indeed recommend to go for $__interval always (with a reasonably setting for min step to avoid that the $__interval becomes too short, something like four times the scrape interval).

This should be "almost" right in probably all the cases. For the related problem of getting "true" coverage, see grafana/grafana#21417

[kyrogue]

This is breaking the master branch.

generated dashboards .json are having the $__interval placeholder, it should be a numeric instead.

Previous changes added the $__interval template , and then removed it , however the $__interval placeholder present in dashboards did not get updated with the appropriate values.

[brancz]

@povilasv can you double check this?

[beorn7]

$__interval is a Grafana-specific thing. Only inside Grafana, it will be populated with a numeric value. Jsonnet has to render it as $__interval.

[povilasv]

My PR (#383) just removed unused variable, don't see how it could break master.

I also tried to generate dashboards from master branch and everything is fine.

This is what get's generated:

               "targets": [
                  {
                     "expr": "(sum(irate(container_network_receive_bytes_total{cluster=\"$cluster\", namespace=~\"$namespace\"}[$__interval])\n* on (namespace,pod)\ngroup_left(workload,workload_type) mixin_pod_workload{cluster=\"$cluster\", namespace=~\"$namespace\", workload_type=\"$type\"}) by (workload))\n",
                     "format": "table",
                     "instant": true,
                     "intervalFactor": 2,
                     "legendFormat": "",
                     "refId": "A",
                     "step": 10
                  },

and it render fine in Grafana.

[kyrogue]

is there additional configuration required in Grafana(6.7.1) for the internal variable $__interval to be rendered? If i were to change $__interval to 5m it will work.

[povilasv]

What's the time range you are looking at and Prometheus scrape interval?

Try increasing the window to last 2 days? Does it render?

[kyrogue]

Ah, increasing Grafana time range to 24 hours worked, anything below does not render.
Thanks.
I suppose this is because the range is too short and Prometheus does not have enough datapoints to render onto the graph panel?

[beorn7]

Yeah, you need to set a Min step or Min time interval.

Shameless plug: I had planned to do a talk about exactly that at Grafanacon. With the conference being Corona-cancelled, there will be some kind of online version of that. See https://grafana.com/about/events/grafanacon/2020/ for more details in the close future.

[povilasv]

👍

I'm closing this issue as it has been solved