nice-grpc-prometheus

Prometheus monitoring for nice-grpc. Uses @prometheus-io/client. Metrics mostly mimic go-grpc-prometheus.

Installation

npm install nice-grpc-prometheus

Usage

Import nice-grpc-prometheus metrics registry and merge it with the global registry:

import {register as globalRegistry, Registry} from '@prometheus-io/client';
import {registry as niceGrpcRegistry} from 'nice-grpc-prometheus';

// use `await mergedRegistry.metrics()` to export all metrics
const mergedRegistry = Registry.merge([globalRegistry, niceGrpcRegistry]);

Attach middleware as the first one on the server:

import {createServer} from 'nice-grpc';
import {prometheusServerMiddleware} from 'nice-grpc-prometheus';

const server = createServer()
  .use(prometheusServerMiddleware())
  .use(/* ... other middleware */);

Attach middleware as the first one on the client:

import {createClientFactory} from 'nice-grpc';
import {prometheusClientMiddleware} from 'nice-grpc-prometheus';

const clientFactory = createClientFactory()
  .use(prometheusClientMiddleware())
  .use(/* ... other middleware */);

const client = clientFactory.create(/* ... */);

Metrics

Following metrics are provided:

Server

| Name | Type | Description | Labels | | -------------------------------- | --------- | ------------------------------------------------------------------------------------------------------ | -------------------- | | grpc_server_started_total | Counter | Total number of RPCs started on the server. | Common (see below) | | grpc_server_handled_total | Counter | Total number of RPCs completed on the server, regardless of success or failure. | Common + grpc_code | | grpc_server_msg_received_total | Counter | Total number of RPC stream messages received by the server. | Common | | grpc_server_msg_sent_total | Counter | Total number of gRPC stream messages sent by the server. | Common | | grpc_server_handling_seconds | Histogram | Histogram of response latency (seconds) of gRPC that had been application-level handled by the server. | Common + grpc_code |

Client

| Name | Type | Description | Labels | | -------------------------------- | --------- | -------------------------------------------------------------------------------------------- | -------------------- | | grpc_client_started_total | Counter | Total number of RPCs started on the client. | Common | | grpc_client_handled_total | Counter | Total number of RPCs completed on the client, regardless of success or failure. | Common + grpc_code | | grpc_client_msg_received_total | Counter | Total number of RPC stream messages received by the client. | Common | | grpc_client_msg_sent_total | Counter | Total number of gRPC stream messages sent by the client. | Common | | grpc_client_handling_seconds | Histogram | Histogram of response latency (seconds) of the gRPC until it is finished by the application. | Common + grpc_code |

Labels

Common labels:

| Name | Description | Examples | | -------------- | ------------------------------ | -------------------------------------------------------- | | grpc_type | Call type | unary, server_stream, client_stream, bidi_stream | | grpc_path | Full path of a method | /my.package.MyService/MyMethod | | grpc_service | Full service name with package | my.package.MyService | | grpc_method | Method name | MyMethod |

Metrics that correspond to finished calls have extra label:

| Name | Description | Examples | | ----------- | ---------------------------------------------------------------------------- | ------------------------------ | | grpc_code | Status code name | OK, CANCELLED, NOT_FOUND |

Customization

You can use your own metric instances. This can be useful for example if you want to use your own buckets in histograms.

import {createClientFactory} from 'nice-grpc';
import {
  labelNamesWithCode,
  prometheusClientMiddleware,
} from 'nice-grpc-prometheus';
import {Histogram, Registry} from '@prometheus-io/client';

const registry = new Registry();

const clientHandlingSecondsMetric = new Histogram({
  registers: [registry],
  name: 'custom_grpc_client_handling_seconds',
  help: 'Custom histogram of response latency (seconds) of the gRPC until it is finished by the application.',
  labelNames: labelNamesWithCode,
  buckets: [0.1, 0.5, 1, 2, 3, 5, 10],
});

const clientFactory = createClientFactory()
  .use(prometheusClientMiddleware({clientHandlingSecondsMetric}))
  .use(/* ... other middleware */);

Don't forget to merge new registry with the global registry or use default registry instead.

Client middleware options:

{
  clientStartedMetric?: Counter; // labelNames: labelNames
  clientHandledMetric?: Counter; // labelNames: labelNamesWithCode
  clientStreamMsgReceivedMetric?: Counter; // labelNames: labelNames
  clientStreamMsgSentMetric?: Counter; // labelNames: labelNames
  clientHandlingSecondsMetric?: Histogram; // labelNames: labelNamesWithCode
}

Server middleware options:

{
  serverStartedMetric?: Counter; // labelNames: labelNames
  serverHandledMetric?: Counter; // labelNames: labelNamesWithCode
  serverStreamMsgReceivedMetric?: Counter; // labelNames: labelNames
  serverStreamMsgSentMetric?: Counter; // labelNames: labelNames
  serverHandlingSecondsMetric?: Histogram; // labelNames: labelNamesWithCode
}

Caution: Use the labelNames specified in the comment. Using incorrect labelNames may cause errors now or in the future.