Dynamically updating one variable based on another (custom variable limitation)

Grafana Dashboards
1

Hi all,

I’m running into a limitation with Grafana’s variable system and would appreciate any advice or potential workarounds.

Use Case:
I have the following variables configured on a dashboard:
• $realm – a query variable fetching available realms from a T2 datasource.
• $region – a query variable dependent on $realm, which fetches regions from the same datasource.
• $Tier – a custom variable with hardcoded values: Tier1, Tier2, Tier3.
• $tier1, $tier2, $tier3 – custom variables with comma-separated regions, like:
• tier1: us-ashburn-1, us-phoenix-1
• tier2: me-dubai-1, eu-zurich-1
• tier3: uk-london-1, eu-paris-1

These tier-region mappings are not stored in the T2 datasource – they are static and only defined within the dashboard as custom variables.

Problem:
I want to dynamically update the $region variable based on the selected $Tier (so users can just pick a tier and see the corresponding regions).

However:

  • The tier-to-region mappings (e.g., Tier1 → us-ashburn-1, us-phoenix-1) are not available in the T2 datasource, so I cannot use a query to fetch region values based on the selected tier.
  • $Tier is a custom variable, and custom variables in Grafana are statically evaluated — their values are treated as plain text and cannot be used to dynamically drive or modify other variables like $region.
  • Grafana does not support indirect referencing, so selecting Tier1 as the value of $Tier does not cause $Tier1 to be interpreted or substituted automatically. In other words, $Tier pointing to Tier1 does not result in $Tier1’s values being resolved or used elsewhere.
  • For example, if I select Tier1 as the value of $Tier, and try to use that to dynamically populate $region via something like $${Tier}, it doesn’t resolve to the contents of $Tier1 (i.e., the actual regions). Grafana does not support indirect referencing like this.
  • I cannot define $region as a custom variable either, because it needs to pull dynamic values from the T2 datasource and support filtering in panel queries — which requires a query variable, not a custom one.

Goal:
When the user selects a value in $Tier, I want $region to automatically update to the regions mapped to that tier (e.g., selecting Tier1 sets $region to us-ashburn-1, us-phoenix-1).

Has anyone faced a similar situation? Is there any workaround or plugin that might help implement this logic?

Thanks in advance!

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Screenshot 2025-07-04 at 12.36.02 PM
Screenshot 2025-07-04 at 12.36.02 PM2832×610 58 KB

3

Yes, use for example SQL datasource and write query (whole business logic will be in SQL), which will return correct region based on tier value

4

So $region will depend both on $Tier and $realm?

$realm (dynamic)
  - realm1
  - realm2

$region (dynamic)
  - region1,realm1
  - region2,realm2

$Tier (static)
  - Tier 1
  - Tier 2

$tier1 (static)
  - us-ashburn-1, us-phoenix-1
$tier2 (static)
  - me-dubai-1, eu-zurich-1
$tier3 (static)
  - uk-london-1, eu-paris-1

does $region have tier data, if so in what form?
what are $region and $realm datasources? sql? a rest api?

5

does $region have tier data, if so in what form?
$region will have all available regions in T2 (based on the passed variable $realm in grafana query variable)
So $region will have data which we want to query using variable $Tier [Tier1, Tier2, Tier2].

what are $region and $realm datasources? sql? a rest api?
We’re using OCI T2 as dataSource here and data being fetched using T2 query in grafana variable.