Grafana Dashboard Template Variable Not Working Fix

In this tutorial, you'll learn about Grafana Dashboard Template Variable Not Working Fix. We cover key concepts, practical examples, and best practices.

Your Grafana dashboard variable shows No data in the dropdown or returns empty results — the variable query is wrong, the datasource can't execute it, or the variable references another variable that isn't loaded yet.

The Problem

Variable: $env (type: Query)
Query: label_values(up, environment)
Result: No data

The metric up exists, but environment is not a label on the up metric. The label might be called env instead, or the metric isn't being scraped from the target environment.

Step-by-Step Fix

1. Verify the label exists

# Check what labels are available on the metric
label_values(node_boot_time_seconds, instance)

Use the Explore tab in Grafana to verify label names before writing variable queries.

2. Fix the variable query

# List all values of the "env" label
label_values(env)

# List values filtered by another variable
label_values(up{job="$job"}, instance)

# Use query_result for complex filtering
query_result(count by(env) (up == 1))

3. Handle multi-value and "All" options

# In variable settings:
Type: Query
Label: Environment
Multi-value: true
Include All option: true
All value: .*

Use =~ regex matching in dashboard queries to support multi-value variables:

up{env=~"$env"}

4. Fix variable dependencies (order matters)

Variables are evaluated in order. If $instance depends on $job, $job must appear first in the variable list. Drag variables to reorder them.

# $job (first)
label_values(up, job)

# $instance (second — uses $job)
label_values(up{job="$job"}, instance)

5. Use custom variables for static values

Type: Custom
Values: production,staging,development
Default: production

Expected output:

Variable: $env
Values: production, staging, development
✓ Variable loaded successfully
✓ Dashboard panels filtering by $env

Prevention Tips

• Order dependent variables correctly (parent before child)
• Use label_values() for simple label lists
• Use query_result() for filtered/complex variables
• Test variable queries in the Explore tab first
• Enable "Multi-value" and "Include All option" for flexible dashboards

Common Mistakes with dashboard variable

1. Non-exhaustive pattern matches that compile with warnings then crash at runtime
2. Misunderstanding that String is [Char] with poor performance for large text operations
3. Using foldl instead of foldl' causing stack overflow on large lists

These mistakes appear frequently in real-world GRAFANA code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

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