Bar Gauge Panels

Introduction

Bar Gauge panels are one of Grafana's most effective visualization tools for displaying single-value metrics with thresholds. Unlike standard gauges that use a dial or meter, Bar Gauges represent values as colored bars, making them excellent for dashboards where you need to monitor multiple related metrics at a glance.

In this guide, you'll learn:

• What Bar Gauge panels are and when to use them
• How to create and configure Bar Gauge panels
• Different display modes and orientation options
• How to set up thresholds and color mapping
• Real-world applications and best practices

What is a Bar Gauge Panel?

A Bar Gauge panel is a visualization type in Grafana that displays single values as colored bars or circles. It's particularly useful for showing:

• Current values against thresholds
• Progress toward goals
• Health status of services or components
• Resource utilization metrics (CPU, memory, disk space)

The key advantage of Bar Gauge panels is their visual clarity and space efficiency - they allow you to display multiple metrics in a compact, easily scannable format.

Creating Your First Bar Gauge Panel

Let's walk through creating a basic Bar Gauge panel in Grafana:

1. From your Grafana dashboard, click the "Add panel" button
2. Select "Add a new panel"
3. In the visualization options, select "Bar Gauge"
4. Configure your data source and query to return a single value

Here's what a simple configuration might look like:

javascript

// Example query returning CPU usage for a server
SELECT
  last("usage_idle")
FROM "cpu"
WHERE $timeFilter
GROUP BY time($__interval)

Display Modes

Bar Gauge panels offer multiple display modes to suit different visualization needs:

1. Basic (Default)

The basic mode displays values as horizontal or vertical bars, depending on your orientation setting.

2. Gradient

Gradient mode applies a color gradient across the bar based on your thresholds, creating a smoother visual transition between states.

3. LCD

LCD mode mimics a digital display, showing the value as segments similar to an LCD screen. This mode works well for numeric displays where you want a technical aesthetic.

4. Retro LCD

A variation of LCD mode with a more vintage appearance, featuring rounded segments.

To change the display mode:

1. Go to the "Display" tab in the panel editor
2. Find the "Display mode" option
3. Select your preferred mode from the dropdown

Orientation Options

Bar Gauge panels can be displayed in different orientations:

• Horizontal (default): Bars extend from left to right
• Vertical: Bars extend from bottom to top

To change orientation:

1. Go to the "Display" tab
2. Find the "Orientation" option
3. Select either "Horizontal" or "Vertical"

Value Display Options

You can customize how values are displayed within your Bar Gauge:

Text Size and Mode

Control the size of text and how it's displayed:

javascript

// Example panel JSON config showing text options
{
  "options": {
    "text": {
      "titleSize": 16,
      "valueSize": 32
    }
  }
}

Units and Decimals

Configure appropriate units and decimal precision:

1. In the "Field" tab, find the "Standard options" section
2. Set the "Unit" to an appropriate measurement (percentage, bytes, etc.)
3. Adjust "Decimals" to control precision

Value Mapping

Map specific numeric values to text for better context:

1. In the "Field" tab, find "Value mappings"
2. Click "Add value mapping"
3. Choose between "Value", "Range", or "Regex" mapping types
4. Define your mappings (e.g., map 0 to "Offline" or 100 to "Full Capacity")

Thresholds and Color Mapping

One of the most powerful features of Bar Gauge panels is threshold-based coloring, which helps highlight values that need attention.

Setting Up Thresholds

1. Go to the "Field" tab in panel edit mode
2. Find "Thresholds" and click "Add threshold"
3. Define your threshold values and corresponding colors

For example, a server health metric might use:

• 0-70: Green (healthy)
• 70-90: Yellow (warning)
• 90-100: Red (critical)

javascript

// Example threshold configuration
{
  "thresholds": {
    "mode": "absolute",
    "steps": [
      { "color": "green", "value": null },
      { "color": "yellow", "value": 70 },
      { "color": "red", "value": 90 }
    ]
  }
}

Color Mode Options

You can choose how colors are applied to your bar gauges:

• Value: Colors only the value text
• Background: Colors the entire background
• Bar: Colors only the bar (most common)

Multiple Stats in One Panel

Bar Gauge panels excel at displaying multiple related metrics in a single panel:

1. Configure your query to return multiple series
2. Each series will automatically be displayed as a separate bar
3. Use the "Layout" options to control how multiple bars are arranged

For instance, to show CPU usage across multiple servers:

javascript

// Example query returning CPU usage for multiple servers
SELECT
  last("usage_idle")
FROM "cpu"
WHERE $timeFilter
GROUP BY "host"

Practical Example: Server Resource Dashboard

Let's create a practical example of using Bar Gauge panels to monitor server resources:

javascript

// CPU Usage Query
SELECT 100 - mean("usage_idle") as "CPU Usage %" 
FROM "cpu" 
WHERE $timeFilter 
GROUP BY time($__interval)

// Memory Usage Query
SELECT mean("used_percent") as "Memory Usage %"
FROM "mem"
WHERE $timeFilter
GROUP BY time($__interval)

// Disk Usage Query
SELECT mean("used_percent") as "Disk Usage %"
FROM "disk"
WHERE $timeFilter
GROUP BY time($__interval)

Configure these with appropriate thresholds:

• 0-60%: Green
• 60-85%: Yellow
• 85-100%: Red

This creates a compact dashboard showing all key server metrics at a glance, with color-coding to immediately highlight potential issues.

Advanced Configurations

Min and Max Values

Control the scale of your bar gauges by setting min and max values:

1. In the "Field" tab under "Standard options"
2. Set "Min" and "Max" values (e.g., 0 and 100 for percentage displays)

Calculation Options

For time series data, you can control how the single value is calculated:

1. In the "Panel options" section
2. Find "Calculation" and select from options like:
   • Last value
   • Mean
   • Max/Min
   • Total

Custom Tooltips

Enhance your Bar Gauge with informative tooltips:

javascript

// Example tooltip configuration
{
  "options": {
    "tooltip": {
      "mode": "single",
      "sort": "none"
    }
  }
}

Real-World Applications

Bar Gauge panels are versatile and can be used in many scenarios:

1. Infrastructure Monitoring

Monitor server farm health with bar gauges showing:

• CPU usage
• Memory utilization
• Network throughput
• Disk space

2. Application Performance

Track application metrics:

• Request latency
• Error rates
• Active users
• Queue depths

3. Business KPIs

Visualize business metrics:

• Sales targets (% achieved)
• Customer satisfaction scores
• Project completion percentages
• Inventory levels

4. IoT and Sensor Data

Display sensor readings:

• Temperature ranges
• Humidity levels
• Battery levels
• Signal strength

Best Practices

DO:

• Use consistent colors across your dashboard
• Group related metrics together
• Set appropriate min/max values for context
• Add clear titles and descriptions
• Use appropriate units

DON'T:

• Mix unrelated metrics in a single panel
• Overcrowd panels with too many bars
• Use Bar Gauges for time series trends (use Graph panels instead)
• Set arbitrary thresholds without business context

Summary

Bar Gauge panels are powerful tools in your Grafana visualization toolkit. They excel at displaying single-value metrics with threshold context in a compact, visually intuitive format. By properly configuring display modes, thresholds, and orientation, you can create information-dense dashboards that communicate status at a glance.

Remember these key points:

• Bar Gauges are ideal for single values, not trends over time
• Use thresholds to add context through color
• Multiple related metrics can be grouped in one panel
• Different display modes (Basic, Gradient, LCD) offer visual variety
• Proper unit selection enhances readability

Additional Resources

• Practice creating different types of Bar Gauge panels with various display modes
• Experiment with combining Bar Gauges with other panel types in a dashboard
• Try creating a resource monitoring dashboard for your own infrastructure

Exercise

Create a dashboard with the following Bar Gauge panels:

1. A horizontal Bar Gauge showing CPU usage
2. A vertical Bar Gauge showing memory usage
3. An LCD-style gauge showing disk space
4. A multi-stat Bar Gauge showing network metrics for different interfaces

Configure appropriate thresholds and experiment with different display options to see which works best for each metric type.