chore(refactor): move metrics instrumentation to middleware

src/metrics.ts

@@ -28,6 +28,12 @@ export const providersUploadSize = new client.Counter({
   labelNames: ['name']
 });
 
+const providersReturnCount = new client.Counter({
+  name: 'providers_return_count',
+  help: 'Number of times each provider have been used',
+  labelNames: ['name']
+});
+
 export const timeIpfsGatewaysResponse = new client.Histogram({
   name: 'ipfs_gateways_response_duration_seconds',
   help: "Duration in seconds of each IPFS gateway's reponse",
@@ -40,3 +46,16 @@ export const ipfsGatewaysReturnCount = new client.Counter({
   help: 'Number of times each gateway have been used',
   labelNames: ['name']
 });
+
+export const providersInstrumentation = (req, res, next) => {
+  const oldJson = res.json;
+  res.json = body => {
+    if (res.statusCode === 200 && body) {
+      providersReturnCount.inc({ name: body.result?.provider || body.provider });
+    }
+
+    res.locals.body = body;
+    return oldJson.call(res, body);
+  };
+  next();
+};

src/rpc.ts

@@ -4,17 +4,18 @@ import { capture } from '@snapshot-labs/snapshot-sentry';
 import { MAX, rpcError, rpcSuccess } from './utils';
 import { set as setAws } from './aws';
 import { JSON_PROVIDERS, default as set } from './providers/';
+import { providersInstrumentation } from './metrics';
 
 const router = express.Router();
 
-router.post('/', async (req, res) => {
+router.post('/', providersInstrumentation, async (req, res) => {
   const { id, params } = req.body;
   try {
     const size = Buffer.from(JSON.stringify(params)).length;
     if (size > MAX) return rpcError(res, 400, 'File too large', id);
     const result = await Promise.any(set(JSON_PROVIDERS, params));
     await setAws(result.cid, params);
-    console.log('Success', result.provider, 'size', size, 'ms', result.ms);
+    console.log('Success', result.provider, 'size', size);
     result.size = size;
     return rpcSuccess(res, result, id);
   } catch (e: any) {

src/upload.ts

@@ -6,6 +6,7 @@ import sharp from 'sharp';
 import { capture } from '@snapshot-labs/snapshot-sentry';
 import { rpcError, rpcSuccess } from './utils';
 import { IMAGE_PROVIDERS, default as set } from './providers/';
+import { providersInstrumentation } from './metrics';
 
 const MAX_INPUT_SIZE = 1024 * 1024;
 const MAX_IMAGE_DIMENSION = 1500;
@@ -16,7 +17,7 @@ const upload = multer({
   limits: { fileSize: MAX_INPUT_SIZE }
 }).single('file');
 
-router.post('/upload', async (req, res) => {
+router.post('/upload', providersInstrumentation, async (req, res) => {
   upload(req, res, async err => {
     try {
       if (err) return rpcError(res, 400, err.message);
@@ -41,6 +42,7 @@ router.post('/upload', async (req, res) => {
         provider: result.provider
       };
       console.log('Upload success', result.provider, result.cid);
+
       return rpcSuccess(res, file);
     } catch (e: any) {
       if (e.message === 'Input buffer contains unsupported image format') {