# Node Membership Rules

Node Membership Rules automate Node organization within Rooms based on host labels. This simplifies infrastructure management by dynamically assigning Nodes to appropriate Rooms, eliminating manual intervention.

**Important**:

- Rules work with all Rooms except the "All Nodes" Room, as it includes all Nodes by default.
- Creating and editing Rules requires Node management permissions.
- Rules are evaluated in real-time as labels change.
- Exclusion rules always override inclusion rules.

## Rule Structure

The rules consist of the following elements:

| Element | Description                                                                                       |
|:--------|:--------------------------------------------------------------------------------------------------|
| Action  | Determines whether matching Nodes will be included or excluded from the Room                      |
| Clauses | Set of conditions that determine which Nodes match the Rule (all must be satisfied - logical AND) |

Each clause consists of:

| Element  | Description                  |
|:---------|:-----------------------------|
| Label    | The host label to check      |
| Value    | The comparison method        |
| Operator | The value to compare against |

Below is a conceptual representation of a rule that includes all production database Nodes. The structure is shown in YAML format for clarity:

```yaml
Action: Include
Clauses:
  - Label: environment
    Operator: equals
    Value: production
  - Label: service-type
    Operator: equals
    Value: database
```

## Rule Evaluation Order

- Inclusion rules are checked first
- Exclusion rules are checked second
  If both match, exclusion wins

## Creating Rules

1. Access Settings
    - Click ⚙️ (Room settings)
    - Select "Nodes" tab
2. Create Rule
    - Click "Add new Rule"
    - Select Action (Include/Exclude)
    - Add clause(s)
    - Save changes

## Membership Status

Nodes can have multiple membership types in a Room:

| Status          | Description                |
|:----------------|:---------------------------|
| STATIC          | Manually added to the Room |
| RULE            | Added by matching Rule(s)  |
| STATIC and RULE | Both manual and Rule-based |

You can view each Node's membership status in the Room's Nodes table under the "Membership" column.