--- title: Variable Types description: OpenObserve dashboard variable types include Query Values, Constant, Textbox, and Custom, each with configuration and use cases for dynamic panel filtering. --- This page describes the types of [variables](./variables-in-openobserve.md), their use cases, and the configuration required for each type. OpenObserve supports the following variable types: ## 1. Query Values This variable dynamically fetches values from a selected field in a stream. It supports both [single-select and multi-select options](./variables-in-openobserve.md#single-select-and-multi-select). **When to use:** When the available values depend on data already ingested, such as identifiers, names, or categories. **Use Case:** Filter the dashboard panels by Pod name using values from logs. ![Query variable](../../../../images/variables-query.png) :::note[Configuration] **Basic**: - **Type of Variable**: Query Values - **Name**: pod - **Label (optional)**: Pod - **Stream Type**: Logs - **Stream**: `default` - **Field**: `k8s_pod_name` - **Default Max Record Size (optional)**: `20` **Advanced:** - **Allow multiple selection**: Enabled - **By Default Select**: First value - **Hide on Dashboard**: Disabled - **Escape Single Quotes**: Disabled ::: **Result**: - This configuration allows users to dynamically select one or more Kubernetes pod names from the logs stream to apply that selection across dashboard panels. - The variable dropdown will display up to `20` pod names retrieved from the `k8s_pod_name` field in the default log stream. These values are based on the most recently ingested records. - The multi-selection option is enabled. Users can select more than one value, and all dashboard panels using `$pod` will update accordingly. :::note[Note] Dropdown menu on the dashboard populated with live values from the data. ::: ## 2. Constant This variable allows you to set a fixed value that cannot be changed by dashboard users. The constant variables are shown on the dashboard as plain text. **When to use:** When the value should always stay the same and must not be changed by anyone using the dashboard. **Use case:** Building a dashboard that focuses only on logs from a specific Kubernetes namespace named ziox. ![Constant variable](../../../../images/constant-variable.png) :::note[Configuration] **Basic**: - **Type of variable**: Constant - **Name**: constant-ziox - **Label (optional)**: Namespace-name-ziox-constant - **Value**: `ziox` **Advanced**: - **Hide on Dashboard**: Disabled - **Escape Single Quotes**: Disabled ::: **Result**: - After saving, this variable always uses `ziox` as the namespace value during query execution. Users cannot modify it from the dashboard interface. - All queries referencing `$constant-ziox` will consistently apply the `ziox` namespace filter. ## 3. Textbox This variable provides a free-form text input field on the dashboard. **When to use:** When users need to manually enter a value that may not exist in the dropdown, such as custom IDs or strings. **Use Case:** You want users to manually enter the cluster name they want to filter logs by. ![Textbox variable](../../../../images/textbox-variable.png) :::note[Configuration] **Basic**: - **Type of variable**: Textbox - **Name**: input-cluster-name - **Label (optional)**: Enter Cluster Name - **Default value (optional)**: `_o2_all_` **Advanced**: - **Hide On Dashboard**: Disabled - **Escape Single Quotes**: Disabled ::: **Result**: - Users will see a text input field labeled **Enter Cluster Name** on the dashboard. - The default value is `_o2_all_`, but users can replace it with any cluster name, such as `prod` or `dev`, at runtime. - All queries using `$input-cluster-name` will include the user-provided input when executed. ### What is `_o2_all_`? - `_o2_all_` is a special keyword used to **match all values** during query execution. - If this is set as the default value, the dashboard will include data from all clusters unless the user enters a specific one. :::note[Notes] - No validation is performed on the input. The value is passed directly into the query. - To match all values, users must enter exactly `_o2_all_`. Writing `ALL`, `all`, or `` will not match all values. ::: ## 4. Custom This variable lets you predefine a list of selectable values. **When to use:** When values are known in advance and should not be fetched from data. **Use Case:** You want to allow users to select a predefined service from a list, such as openobserve or ingress-nginx. This is useful when the possible values are known and limited, and you want to control what the user can select. ![Custom variable](../../../../images/custom-variable.png) :::note[Configuration] **Basic**: - **Type of variable**: Custom - **Name**: service-name - **Label (optional)**: Service Name - **Label**: `openobserve` - **Value**: `openobserve` - **Default**: Checked - **Label**: `ingress-nginx` - **Value**: `ingress-nginx` - **Default**: Unchecked **Advanced**: - **Allow multiple selection**: Disabled - **Hide on Dashboard**: Disabled - **Escape Single Quotes**: Disabled ::: **Result**: - Users will see a dropdown named **Service Name** with the default selection set to `openobserve`. - They can switch to `ingress-nginx` if needed. The multiple selection option is disabled, so only one option can be selected. - All queries using `$service-name` will include the selected value when executed. :::note[Note] - One value must be selected as the default. - Labels are shown on the dashboard, while values are used in the query. - The values are injected into queries as-is. No validation or transformation is applied. ::: ## Next Steps - Learn how to [apply variables to a panel](./variables-in-openobserve.md#apply-the-variable-to-a-panel). - Learn about [variable dependencies](./variable-dependencies.md).