[plugin/prometheus] Fix duplicated metrics (#3251)

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

.changeset/@graphql-yoga_plugin-prometheus-3251-dependencies.md

@@ -0,0 +1,7 @@
+---
+'@graphql-yoga/plugin-prometheus': patch
+---
+dependencies updates:
+  - Updated dependency [`@envelop/prometheus@^10.0.0`
+    ↗︎](https://www.npmjs.com/package/@envelop/prometheus/v/10.0.0) (from `^9.4.0`, in
+    `dependencies`)

.changeset/big-students-grin.md

@@ -0,0 +1,85 @@
+---
+'@graphql-yoga/plugin-prometheus': major
+---
+
+Adds a cache for metrics definition (Summary, Histogram and Counter).
+
+Fixes an issue preventing this plugin to be initialized multiple times, leading to metrics
+duplication error (https://github.com/ardatan/graphql-mesh/issues/6545).
+
+## Behavior Breaking Change:
+
+Due to Prometheus client API limitations, a metric is only defined once for a given registry. This
+means that if the configuration of the metrics, it will be silently ignored on plugin
+re-initialization.
+
+This is to avoid potential loss of metrics data produced between the plugin re-initialization and
+the last pull by the prometheus agent.
+
+If you need to be sure metrics configuration is up to date after a plugin re-initialization, you can
+either:
+
+- restart the whole node process instead of just recreating a graphql server at runtime
+- clear the registry using `registry.clear()` before plugin re-initialization:
+  ```ts
+  function usePrometheusWithReset() {
+    registry.clear()
+    return usePrometheus({ ... })
+  }
+  ```
+- use a new registry for each plugin instance:
+  ```ts
+  function usePrometheusWithRegistry() {
+    const registry = new Registry()
+    return usePrometheus({
+      registry,
+      ...
+    })
+  }
+  ```
+
+Keep in mind that this implies potential data loss in pull mode.
+
+## API Breaking Change:
+
+To ensure metrics from being registered multiple times on the same registry, the signature of
+`createHistogram`, `createSummary` and `createCounter` have been changed to now include the registry
+as a mandatory parameter.
+
+If you were customizing metrics parameters, you will need to update the metric definitions
+
+```diff
+usePrometheus({
+  execute: createHistogram({
++   registry: registry
+    histogram: new Histogram({
+      name: 'my_custom_name',
+      help: 'HELP ME',
+      labelNames: ['opText'] as const,
+-     registers: [registry],
+    }),
+    fillLabelsFn: () => {}
+  }),
+  requestCount: createCounter({
++   registry: registry
+    histogram: new Histogram({
+      name: 'my_custom_name',
+      help: 'HELP ME',
+      labelNames: ['opText'] as const,
+-     registers: [registry],
+    }),
+    fillLabelsFn: () => {}
+  }),
+  requestSummary: createSummary({
++   registry: registry
+    histogram: new Histogram({
+      name: 'my_custom_name',
+      help: 'HELP ME',
+      labelNames: ['opText'] as const,
+-     registers: [registry],
+    }),
+    fillLabelsFn: () => {}
+  }),
+})
+```
+

packages/plugins/prometheus/package.json

@@ -42,7 +42,7 @@
     "prom-client": "^15.0.0"
   },
   "dependencies": {
-    "@envelop/prometheus": "^9.4.0"
+    "@envelop/prometheus": "^10.0.0"
   },
   "devDependencies": {
     "prom-client": "15.0.0"

packages/plugins/prometheus/src/index.ts

@@ -1,16 +1,27 @@
 import { getOperationAST } from 'graphql';
 import { Plugin } from 'graphql-yoga';
-import { register as defaultRegistry, Histogram } from 'prom-client';
+import { register as defaultRegistry } from 'prom-client';
 import {
+  CounterAndLabels,
   createCounter,
   createHistogram,
   createSummary,
   PrometheusTracingPluginConfig as EnvelopPrometheusTracingPluginConfig,
   FillLabelsFnParams,
+  HistogramAndLabels,
+  SummaryAndLabels,
   usePrometheus as useEnvelopPrometheus,
 } from '@envelop/prometheus';
 
-export { createCounter, createHistogram, createSummary, FillLabelsFnParams };
+export {
+  CounterAndLabels,
+  FillLabelsFnParams,
+  HistogramAndLabels,
+  SummaryAndLabels,
+  createCounter,
+  createHistogram,
+  createSummary,
+};
 
 export interface PrometheusTracingPluginConfig extends EnvelopPrometheusTracingPluginConfig {
   http?: boolean | string | ReturnType<typeof createHistogram>;
@@ -46,12 +57,12 @@ export function usePrometheus(options: PrometheusTracingPluginConfig): Plugin {
       typeof options.http === 'object'
         ? options.http
         : createHistogram({
-            histogram: new Histogram({
+            registry,
+            histogram: {
               name: typeof options.http === 'string' ? options.http : 'graphql_yoga_http_duration',
               help: 'Time spent on HTTP connection',
               labelNames,
-              registers: [registry],
-            }),
+            },
             fillLabelsFn(params, { request, response }) {
               const labels: Record<string, string> = {
                 method: request.method,

packages/plugins/prometheus/tests/prometheus.spec.ts

@@ -122,4 +122,15 @@ describe('Prometheus', () => {
     expect(metrics).toContain('method="POST"');
     expect(metrics).toContain('statusCode="200"');
   });
+
+  it('should be able to register the same histogram for multiple different registries', async () => {
+    usePrometheus({
+      http: true,
+      registry,
+    });
+    usePrometheus({
+      http: true,
+      registry,
+    });
+  });
 });