Fix Grafana Dashboard Variables Not Working

What's Actually Happening

Grafana dashboard variables do not populate with values, or variable selection does not update panels.

The Error You'll See

Variable dropdown empty:

Variable: server
No options found

Query error:

Variable Query Error
Failed to evaluate query

Panel not updating:

# Selecting variable value doesn't update panel data

Template error:

Templating
Failed to upgrade legacy queries

Why This Happens

1. 1.Data source error - Data source query fails
2. 2.Query syntax wrong - Variable query incorrect
3. 3.Variable name mismatch - Wrong variable name in panel
4. 4.Permission issue - User lacks query permission
5. 5.Data source not configured - Missing or wrong data source
6. 6.Variable dependency - Dependent variable not resolving

Step 1: Check Variable Configuration

```bash # View variable settings: # Dashboard -> Settings -> Variables

# Check variable definition: # Name: server # Type: Query # Data source: Prometheus # Query: label_values(up, instance)

# Test variable query: # In variable edit, click "Preview values"

# Check variable types: # Query - Values from data source query # Custom - Manually defined values # Constant - Fixed value # Text box - User input # Interval - Time intervals # Data source - Select data source

# Test query in Explore: # Grafana -> Explore -> Run same query label_values(up, instance) ```

Step 2: Fix Prometheus Variable Queries

```bash # Common Prometheus variable queries:

# Get all label values: label_values(metric_name, label_name)

# Get all instances: label_values(up, instance)

# Get all job names: label_values(up, job)

# Get all metric names: metrics()

# Get metric names with prefix: metrics(http_.*)

# Query with filter: label_values({job="nginx"}, instance)

# Use query result: query_result(count by (instance) (up))

# Regex extraction from values: label_values(up, instance) -> Regex: /([^:]+):.*/ ```

Step 3: Fix InfluxDB Variable Queries

```bash # InfluxDB variable queries:

# Show measurements: SHOW MEASUREMENTS

# Show tag keys: SHOW TAG KEYS FROM "measurement"

# Show tag values: SHOW TAG VALUES FROM "measurement" WITH KEY = "tag_key"

# Show field keys: SHOW FIELD KEYS

# With regex: SHOW TAG VALUES FROM "measurement" WITH KEY = "host" WHERE "region" =~ /^$region$/

# Flux query (InfluxDB 2.x): import "influxdata/influxdb/schema" schema.tagValues(bucket: "bucket", tag: "host") ```

Step 4: Fix Elasticsearch Variable Queries

```bash # Elasticsearch variable queries:

# Find unique values: { "find": "terms", "field": "host.keyword" }

# With query filter: { "find": "terms", "field": "host.keyword", "query": "status:200" }

# Buckets query: { "bucketAggs": [ { "type": "terms", "field": "host.keyword", "settings": { "size": "100" } } ], "metrics": [{"type": "count", "id": "1"}] } ```

Step 5: Fix Variable Dependencies

```bash # Chained variables - one depends on another:

# Variable 1: region # Query: label_values(aws_ec2_instances, region)

# Variable 2: instance (depends on region) # Query: label_values(aws_ec2_instances{region="$region"}, instance)

# Note the $region syntax

# Check dependency order: # Variables are evaluated in order # Dependent variables must come after

# Common issues: # - Wrong variable name ($region vs $Region) # - Variable not defined yet # - Circular dependency

# Test each variable individually: # Disable dependency, test parent variable ```

Step 6: Check Variable Syntax in Panels

```bash # Using variables in panel queries:

# Prometheus: up{instance="$server"} up{instance=~"$server"} # Regex match (multi-select) up{instance!~"$server"} # Negative regex

# InfluxDB: SELECT value FROM cpu WHERE host = '$server' SELECT value FROM cpu WHERE host =~ /^$server$/

# Elasticsearch: host: "$server" host.keyword: "$server"

# Variable formats: # $var - Simple reference # ${var} - With braces (recommended) # [[var]] - Old format (deprecated)

# Multi-select variables: # $var = value1|value2|value3 # Use regex match: instance=~"$var"

# All option: # Enable "Include All option" # $var = .* for all ```

Step 7: Check Data Source Configuration

```bash # Check data source: # Configuration -> Data Sources -> Select data source

# Test connection: # Click "Save & Test"

# Check data source permissions: # User must have access to data source

# Check data source variables: # Type: Data source variable # Query: prometheus, influxdb, etc.

# Check default data source: # Variables use default if not specified

# Verify data source in query: # Panel -> Query -> Data source dropdown ```

Step 8: Debug Variable Queries

```bash # Enable query inspector: # Panel -> Query Inspector

# Check query sent to data source: # Shows expanded variable values

# Check variable resolution: # Dashboard -> View variable values: # Click variable dropdown -> Show all

# Use Grafana API to debug: curl -u admin:password http://grafana:3000/api/dashboards/uid/dashboard-uid | jq .dashboard.templating

# Check server logs: docker logs grafana journalctl -u grafana-server

# Enable debug logging: # In grafana.ini: [log] level = debug ```

Step 9: Fix Common Variable Issues

```bash # Issue 1: Variable shows "No options"

# Fix: Check query returns data # Test in Explore view first

# Issue 2: Variable shows IDs instead of names

# Fix: Add label transformation label_values(metric{label!=""}, label)

# Issue 3: Multi-select not working

# Fix: Use regex match in query instance=~"$var" # Not instance="$var"

# Issue 4: Refresh not updating values

# Fix: Set refresh option # Variable -> Refresh -> On Dashboard Load / On Time Range Change

# Issue 5: Sorting wrong

# Fix: Set sort option # Variable -> Sort -> Alphabetical (asc/desc)

# Issue 6: Custom values not working

# Fix: Use correct format # Values separated by comma: value1,value2,value3 # Or with display: text:value, text2:value2 ```

Step 10: Grafana Variable Verification Script

```bash # Create verification script: cat << 'EOF' > /usr/local/bin/check-grafana-vars.sh #!/bin/bash

GRAFANA_URL=${1:-"http://localhost:3000"} DASHBOARD_UID=${2:-""} USER=${3:-"admin"} PASS=${4:-"admin"}

echo "=== Grafana Status ===" curl -s -u $USER:$PASS $GRAFANA_URL/api/health | jq .

if [ -n "$DASHBOARD_UID" ]; then echo "" echo "=== Dashboard Variables ===" curl -s -u $USER:$PASS $GRAFANA_URL/api/dashboards/uid/$DASHBOARD_UID | \ jq '.dashboard.templating.list[] | {name: .name, type: .type, query: .query, current: .current}'

echo "" echo "=== Variable Values ===" VARS=$(curl -s -u $USER:$PASS $GRAFANA_URL/api/dashboards/uid/$DASHBOARD_UID | \ jq -r '.dashboard.templating.list[].name')

for var in $VARS; do echo "Variable: $var" curl -s -u $USER:$PASS "$GRAFANA_URL/api/dashboards/uid/$DASHBOARD_UID/variables" | \ jq --arg v "$var" '.[] | select(.name == $v) | .current' done fi

echo "" echo "=== Data Sources ===" curl -s -u $USER:$PASS $GRAFANA_URL/api/datasources | jq '.[] | {name: .name, type: .type, isDefault: .isDefault}'

echo "" echo "=== Recent Dashboard Errors ===" docker logs grafana 2>&1 | grep -i "variable|template" | tail -10 EOF

chmod +x /usr/local/bin/check-grafana-vars.sh

# Usage: /usr/local/bin/check-grafana-vars.sh http://grafana:3000 dashboard-uid admin password

# Quick variable test: alias grafana-vars='curl -s -u admin:password http://localhost:3000/api/dashboards/uid/UID | jq .dashboard.templating' ```

Grafana Variable Checklist

Verify the Fix

```bash # After fixing variable issue

# 1. Check variable dropdown # Open dashboard, click variable // Options populated

# 2. Select value # Choose a value // Panels update

# 3. Test multi-select # Select multiple values // All included in query

# 4. Test "All" option # Select "All" // All values included

# 5. Check query inspector # Panel -> Query Inspector // Variable expanded correctly

# 6. Refresh dashboard # Reload dashboard // Variables refresh ```

Related Issues

• [Fix Grafana Dashboard Not Loading](/articles/fix-grafana-dashboard-not-loading)
• [Fix Prometheus Scrape Error](/articles/fix-prometheus-scrape-error)
• [Fix Grafana Data Source Connection Failed](/articles/fix-grafana-data-source-connection-failed)