Metrics API

Overview

In Lasso RPC Core v0.5.0, the metrics API reports a chain in the default public profile, including provider statistics, RPC method performance, and VM resource usage. It does not accept a profile parameter or report a chain configured only in a custom profile.

Endpoint

GET /api/metrics/:chain

Path Parameters

string

required

A chain identifier in public (e.g., ethereum, polygon, arbitrum)

Response

string

required

The chain identifier

integer

required

The numeric chain ID (e.g., 1 for Ethereum)

integer

required

Unix timestamp in milliseconds when metrics were collected

object

required

VM and system resource utilization

Show system_metrics properties

number

Total memory usage in megabytes

number

CPU utilization percentage

integer

Number of active Erlang processes

integer

Number of processes waiting to run

object

required

Aggregated performance metrics for the chain

Show chain_performance properties

integer

Total number of RPC calls processed

number

Success rate percentage (0-100)

number

50th percentile latency in milliseconds

number

95th percentile latency in milliseconds

null

Reserved field; the released endpoint returns null

integer

Number of providers currently connected and healthy

integer

Total number of configured providers for this chain

null

Reserved field; the released endpoint returns null

null

Reserved field; the released endpoint returns null

number

Error rate percentage (0-100)

array

required

Performance metrics for each provider

Show provider properties

string

Provider identifier

string

Human-readable provider name

number

Relative provider ranking score; not a percentage or fixed 0-100 range

number

Success fraction for this provider (0-1), rounded to two decimals

integer

Upstream attempts recorded for this provider

number

Average response latency in milliseconds

integer

Number of calls in the last minute

array

required

List of RPC methods that have been called on this chain

array

Detailed RPC method performance organized by provider

Show structure

string

Provider identifier

string

Provider name

array

Performance data for each RPC method on this provider

Show method properties

string

RPC method name (e.g., eth_blockNumber)

number

Average latency in milliseconds

number

50th percentile latency

number

90th percentile latency

number

95th percentile latency

number

99th percentile latency

number

Success rate for this method (0-1)

integer

Number of calls to this method

integer

Timestamp of last update

array

Detailed RPC method performance organized by method

Show structure

string

RPC method name

array

Performance data for each provider supporting this method (same structure as methods above, with added provider_id and provider_name)

integer

required

Timestamp when metrics were last updated

Response Example

{
  "chain": "ethereum",
  "chain_id": 1,
  "timestamp": 1709502330123,
  "system_metrics": {
    "memory_mb": 245.6,
    "cpu_percent": 12.4,
    "process_count": 542,
    "run_queue": 0
  },
  "chain_performance": {
    "total_calls": 15234,
    "success_rate": 99.2,
    "p50_latency": 125.5,
    "p95_latency": 342.1,
    "failovers_last_minute": null,
    "connected_providers": 3,
    "total_providers": 3,
    "recent_activity": null,
    "rpc_calls_per_second": null,
    "error_rate_percent": 0.8
  },
  "providers": [
    {
      "id": "alchemy-eth-mainnet",
      "name": "Alchemy",
      "score": 3.51,
      "success_rate": 1.0,
      "total_calls": 8432,
      "avg_latency_ms": 115.3,
      "calls_last_minute": 28
    },
    {
      "id": "infura-eth-mainnet",
      "name": "Infura",
      "score": 3.16,
      "success_rate": 0.99,
      "total_calls": 4521,
      "avg_latency_ms": 145.8,
      "calls_last_minute": 12
    },
    {
      "id": "quicknode-eth-mainnet",
      "name": "QuickNode",
      "score": 2.96,
      "success_rate": 0.99,
      "total_calls": 2281,
      "avg_latency_ms": 128.2,
      "calls_last_minute": 5
    }
  ],
  "rpc_methods": [
    "eth_blockNumber",
    "eth_getBlockByNumber",
    "eth_call",
    "eth_getLogs"
  ],
  "rpc_performance_by_provider": [
    {
      "provider_id": "alchemy-eth-mainnet",
      "provider_name": "Alchemy",
      "methods": [
        {
          "method": "eth_blockNumber",
          "avg_latency_ms": 45.2,
          "p50_latency_ms": 42.0,
          "p90_latency_ms": 68.5,
          "p95_latency_ms": 85.3,
          "p99_latency_ms": 124.7,
          "success_rate": 0.998,
          "total_calls": 3421,
          "last_updated": 1709502330100
        }
      ]
    }
  ],
  "rpc_performance_by_method": [
    {
      "method": "eth_blockNumber",
      "providers": [
        {
          "provider_id": "alchemy-eth-mainnet",
          "provider_name": "Alchemy",
          "avg_latency_ms": 45.2,
          "p50_latency_ms": 42.0,
          "p90_latency_ms": 68.5,
          "p95_latency_ms": 85.3,
          "p99_latency_ms": 124.7,
          "success_rate": 0.998,
          "total_calls": 3421,
          "last_updated": 1709502330100
        }
      ]
    }
  ],
  "last_updated": 1709502330100
}

Error Responses

Chain Not Found

{
  "error": "Chain not found",
  "chain": "invalid-chain",
  "available_chains": ["ethereum", "polygon", "arbitrum"]
}

HTTP Status: 404 Not Found This includes chains configured only in another profile. The response’s available_chains lists canonical chain names in public; see the released metrics controller.

Use Cases

Monitor Chain Performance

Track overall performance metrics for a blockchain:

curl http://localhost:4000/api/metrics/ethereum

Provider Performance Comparison

Compare performance across different RPC providers:

# Get provider rankings
curl -s http://localhost:4000/api/metrics/ethereum | \
  jq '.providers | sort_by(-.score) | .[] | {name, score, success_rate, avg_latency_ms}'

RPC Method Analysis

Analyze performance of specific RPC methods:

# Check eth_getLogs performance across providers
curl -s http://localhost:4000/api/metrics/ethereum | \
  jq '.rpc_performance_by_method[] | select(.method=="eth_getLogs")'

System Resource Monitoring

Monitor system resource usage:

# Alert if memory usage is high
memory_mb=$(curl -s http://localhost:4000/api/metrics/ethereum | jq '.system_metrics.memory_mb')

if (( $(echo "$memory_mb > 1000" | bc -l) )); then
  echo "Warning: High memory usage: ${memory_mb}MB"
fi

Performance Dashboards

Transform the JSON values for your monitoring backend. For native Prometheus text, scrape GET /metrics on each node; see metrics. The JSON endpoint remains useful when you need the chain and provider fields:

// Fetch metrics periodically
setInterval(async () => {
  const response = await fetch('http://localhost:4000/api/metrics/ethereum');
  const metrics = await response.json();
  
  // Send to monitoring backend
  await sendToDatadog({
    'lasso.chain.success_rate': metrics.chain_performance.success_rate,
    'lasso.chain.p95_latency': metrics.chain_performance.p95_latency,
    'lasso.chain.total_calls': metrics.chain_performance.total_calls,
    'lasso.system.memory_mb': metrics.system_metrics.memory_mb,
    'lasso.system.cpu_percent': metrics.system_metrics.cpu_percent
  });
}, 30000); // Every 30 seconds

rpc_calls_per_second, failovers_last_minute, and recent_activity are reserved fields that return null in v0.5.0. Derive a rate from successive total_calls samples if your monitoring system needs one.

Notes

Available values reflect retained in-process upstream-attempt observations.
Performance percentiles (p50, p95, etc.) are calculated over a sliding window
Provider scores combine the success fraction, average latency, and observation count. They rank providers within the retained data; they are not percentages.
The rpc_performance_by_provider and rpc_performance_by_method fields provide the same data organized differently for convenience
System metrics reflect the Erlang VM’s resource usage, not the underlying host system

HTTP API

WebSocket API

Status and metrics

Reference

Releases and evidence

Overview

Endpoint

Path Parameters

Response

Response Example

Error Responses

Chain Not Found

Use Cases

Monitor Chain Performance

Provider Performance Comparison

RPC Method Analysis

System Resource Monitoring

Performance Dashboards

Notes

​Overview

​Endpoint

​Path Parameters

​Response

​Response Example

​Error Responses

​Chain Not Found

​Use Cases

​Monitor Chain Performance

​Provider Performance Comparison

​RPC Method Analysis

​System Resource Monitoring

​Performance Dashboards

​Notes

Overview

Endpoint

Path Parameters

Response

Response Example

Error Responses

Chain Not Found

Use Cases

Monitor Chain Performance

Provider Performance Comparison

RPC Method Analysis

System Resource Monitoring

Performance Dashboards

Notes