Grafana Variables
Variables make dashboards interactive and reusable. Instead of building a separate dashboard for every server, you build one dashboard with a variable that lets you pick the server from a dropdown at the top. The entire dashboard updates instantly to show data for the chosen server.
The TV Remote Analogy
A variable works like a TV remote control. The remote does not change the TV hardware — it changes what the TV displays. A Grafana variable does not change the dashboard structure — it changes which data the panels show. One dashboard, unlimited views.
Dashboard with variable: ┌─────────────────────────────────────────────────┐ │ Server: [server-01 ▼] Region: [US-East ▼] │ ← dropdowns ├─────────────────────────────────────────────────┤ │ CPU Usage for server-01 Memory for server-01 │ │ [live chart] [live chart] │ └─────────────────────────────────────────────────┘ Change dropdown to server-02: ┌─────────────────────────────────────────────────┐ │ Server: [server-02 ▼] Region: [US-East ▼] │ ├─────────────────────────────────────────────────┤ │ CPU Usage for server-02 Memory for server-02 │ │ [live chart] [live chart] │ └─────────────────────────────────────────────────┘
Types of Variables
Query Variable
A query variable runs a query against your data source and populates the dropdown with the results. For example, a Prometheus query can return all instance names currently being monitored, and those names fill the dropdown automatically. When you add a new server, it appears in the dropdown without any manual update.
Query: label_values(up, instance) Result: server-01 server-02 server-03
Custom Variable
A custom variable holds a fixed list of values you type manually, separated by commas. Use it when the list does not come from a data source — for example, environment names like dev,staging,production.
Constant Variable
A constant variable stores a single fixed value used across the dashboard. It is invisible to users but useful for storing values like a base URL or an org name that every panel references.
Text Box Variable
A text box variable shows a free-text input field at the top of the dashboard. Users type any value and queries use that typed value as a filter. Useful for filtering by a specific job name or customer ID.
Interval Variable
An interval variable lets users choose the time grouping for queries — for example, 1 minute, 5 minutes, or 1 hour. Use it in Prometheus rate() functions so users can adjust chart smoothness.
Data Source Variable
A data source variable lists all connected data sources of a given type. Users can switch between different Prometheus instances (for example, prod vs dev) using one dropdown on the dashboard.
Creating a Query Variable – Step by Step
Step 1 – Open Dashboard Settings
Click the gear icon (⚙) at the top of the dashboard to open Settings. In Grafana 10 and later, click the settings menu button in the dashboard toolbar.
Step 2 – Navigate to Variables
Click Variables in the left settings menu. Click Add variable.
Step 3 – Configure the Variable
Variable type: Query Name: instance Label: Server Data source: Prometheus Query: label_values(up, instance)
The Name is used inside queries with a dollar sign prefix: $instance. The Label is the friendly text displayed above the dropdown on the dashboard.
Step 4 – Enable Multi-Select (Optional)
Toggle Multi-value to allow users to select more than one option at once. Toggle Include All option to add an "All" choice that selects every value simultaneously.
Step 5 – Save the Variable
Click Update and then save the dashboard. The dropdown now appears at the top of the dashboard.
Using Variables in Queries
Reference a variable inside any query using the $variable_name syntax. When the user selects a value from the dropdown, Grafana substitutes the variable with the selected value before sending the query.
Query without variable (hardcoded):
rate(node_cpu_seconds_total{instance="server-01"}[5m])
Query with variable (dynamic):
rate(node_cpu_seconds_total{instance="$instance"}[5m])
Switching the dropdown from server-01 to server-02 instantly replaces $instance with server-02 in every panel that uses this variable.
Chained Variables
Variables can depend on each other. A Region variable filters the list shown in a Server variable. When the user picks a region, the server dropdown refreshes to show only servers in that region.
User picks Region → [US-East] │ ▼ Server dropdown refreshes → shows only US-East servers │ ▼ Dashboard panels show data for selected server in US-East
To chain variables, reference the parent variable in the child variable's query:
Region variable query: label_values(up, region)
Server variable query: label_values(up{region="$region"}, instance)
Using Variables in Panel Titles
You can embed variables in panel titles, making it clear which data the panel currently shows. Set the panel title to:
CPU Usage — $instance
When the user selects server-02, the panel title automatically updates to CPU Usage — server-02.
Repeating Panels with Variables
Grafana can automatically repeat a panel for each selected value in a multi-value variable. Enable this in the panel editor under Panel options → Repeat options → Repeat by variable. Select your variable. Grafana generates one copy of the panel per selected value, arranged in a grid.
Variable: $instance = [server-01, server-02, server-03] Repeat panel enabled: [CPU: server-01] [CPU: server-02] [CPU: server-03]