Type Alias NodeMetadata 

pub type NodeMetadata = Value;

Schema-less metadata for nodes.

This type alias provides maximum flexibility for arbitrary node metadata. Nodes can report any JSON-serializable data (CPU load, memory, custom metrics, etc.) and consumers (like load balancers) can interpret the metadata as needed.

Common Metadata Keys

While the schema is flexible, these keys are commonly used:

• cpu_usage_percent: CPU usage as percentage (0.0 - 100.0)
• memory_usage_percent: Memory usage as percentage (0.0 - 100.0)
• memory_available_bytes: Available memory in bytes
• load_avg_1m: 1-minute load average
• active_connections: Number of active connections
• requests_per_second: Request rate
• queue_depth: Request queue depth

Example

use serde_json::json;

let metadata = json!({
    "cpu_usage_percent": 45.5,
    "memory_usage_percent": 62.0,
    "custom_metric": "value"
});

Aliased Type

pub enum NodeMetadata {
    Null,
    Bool(bool),
    Number(Number),
    String(String),
    Array(Vec<Value>),
    Object(Map<String, Value>),
}

Variants

Null

Represents a JSON null value.

let v = json!(null);

Bool(bool)

Represents a JSON boolean.

let v = json!(true);

Number(Number)

Represents a JSON number, whether integer or floating point.

let v = json!(12.5);

String(String)

Represents a JSON string.

let v = json!("a string");

Array(Vec<Value>)

Represents a JSON array.

let v = json!(["an", "array"]);

Object(Map<String, Value>)

Represents a JSON object.

By default the map is backed by a BTreeMap. Enable the preserve_order feature of serde_json to use IndexMap instead, which preserves entries in the order they are inserted into the map. In particular, this allows JSON data to be deserialized into a Value and serialized to a string while retaining the order of map keys in the input.

let v = json!({ "an": "object" });