add: error object to custom retry callback (#337)

MikePresman · web-flow · commit 5f3fbb992333 · 2024-01-04T09:59:56.000+01:00
diff --git a/README.md b/README.md
@@ -268,18 +268,24 @@ By Default: 10
 
 ---
 
-### `customRetry`
+### `retryDelay`
 
 - `handler`. Required
-- `retries`. Optional
 
-This plugin gives the client an option to pass their own retry callback to handle retries on their own.
-If a `handler` is passed to the `customRetry` object the onus is on the client to invoke the default retry logic in their callback otherwise default cases such as 503 will not be handled
+This plugin gives the client an option to pass their own retry callback to allow the client to define what retryDelay they would like on any retries
+outside the scope of what is handled by default in fastify-reply-from. To see the default please refer to index.js `getDefaultDelay()`
+If a `handler` is passed to the `retryDelay` object the onus is on the client to invoke the default retry logic in their callback otherwise default cases such as 500 will not be handled
+
+- `err` is the error thrown by making a request using whichever agent is configured
+- `req` is the raw request details sent to the underlying agent. __Note__: this object is not a Fastify request object, but instead the low-level request for the agent.
+- `res` is the raw response returned by the underlying agent (if available) __Note__: this object is not a Fastify response, but instead the low-level response from the agent. This property may be null if no response was obtained at all, like from a connection reset or timeout.
+- `attempt` in the object callback refers to the current retriesAttempt number. You are given the freedom to use this in concert with the retryCount property set to handle retries
+- `getDefaultRetry` refers to the default retry handler. If this callback returns not null and you wish to handle those case of errors simply invoke it as done below.
 
 Given example
 
 ```js
-  const customRetryLogic = (req, res, getDefaultRetry) => {
+   const customRetryLogic = ({err, req, res, attempt, getDefaultRetry}) => {
     //If this block is not included all non 500 errors will not be retried
     const defaultDelay = getDefaultDelay();
     if (defaultDelay) return defaultDelay();
@@ -288,18 +294,31 @@ Given example
     if (res && res.statusCode === 500 && req.method === 'GET') {
       return 300
     }
+
+    if (err && err.code == "UND_ERR_SOCKET"){
+      return 600
+    }
+
     return null
   }
 
 .......
 
 fastify.register(FastifyReplyFrom, {
   base: 'http://localhost:3001/',
-  customRetry: {handler: customRetryLogic, retries: 10}
+  retryDelay: customRetryLogic
 })
 
 ```
 
+Note the Typescript Equivalent
+```
+const customRetryLogic = ({req, res, err, getDefaultRetry}: RetryDetails) => {
+  ...
+}
+...
+
+```
 ---
 
 ### `reply.from(source, [opts])`
diff --git a/index.js b/index.js
@@ -59,7 +59,7 @@ const fastifyReplyFrom = fp(function from (fastify, opts, next) {
     const onError = opts.onError || onErrorDefault
     const retriesCount = opts.retriesCount || 0
     const maxRetriesOn503 = opts.maxRetriesOn503 || 10
-    const customRetry = opts.customRetry || undefined
+    const retryDelay = opts.retryDelay || undefined
 
     if (!source) {
       source = req.url
@@ -142,38 +142,32 @@ const fastifyReplyFrom = fp(function from (fastify, opts, next) {
     const requestHeaders = rewriteRequestHeaders(this.request, headers)
     const contentLength = requestHeaders['content-length']
     let requestImpl
-    if (retryMethods.has(method) && !contentLength) {
-      const retryHandler = (req, res, err, retries) => {
-        const defaultDelay = () => {
-          // Magic number, so why not 42? We might want to make this configurable.
-          let retryAfter = 42 * Math.random() * (retries + 1)
-
-          if (res && res.headers['retry-after']) {
-            retryAfter = res.headers['retry-after']
-          }
-          if (res && res.statusCode === 503 && req.method === 'GET') {
-            if (retriesCount === 0 && retries < maxRetriesOn503) {
-              // we should stop at some point
-              return retryAfter
-            }
-          } else if (retriesCount > retries && err && err.code === retryOnError) {
-            return retryAfter
-          }
-          return null
-        }
 
-        if (customRetry && customRetry.handler) {
-          const customRetries = customRetry.retries || 1
-          if (++retries < customRetries) {
-            return customRetry.handler(req, res, defaultDelay)
+    const getDefaultDelay = (req, res, err, retries) => {
+      if (retryMethods.has(method) && !contentLength) {
+        // Magic number, so why not 42? We might want to make this configurable.
+        let retryAfter = 42 * Math.random() * (retries + 1)
+
+        if (res && res.headers['retry-after']) {
+          retryAfter = res.headers['retry-after']
+        }
+        if (res && res.statusCode === 503 && req.method === 'GET') {
+          if (retriesCount === 0 && retries < maxRetriesOn503) {
+            return retryAfter
           }
+        } else if (retriesCount > retries && err && err.code === retryOnError) {
+          return retryAfter
         }
-        return defaultDelay()
       }
+      return null
+    }
 
-      requestImpl = createRequestRetry(request, this, retryHandler)
+    if (retryDelay) {
+      requestImpl = createRequestRetry(request, this, (req, res, err, retries) => {
+        return retryDelay({ err, req, res, attempt: retries, getDefaultDelay })
+      })
     } else {
-      requestImpl = request
+      requestImpl = createRequestRetry(request, this, getDefaultDelay)
     }
 
     requestImpl({ method, url, qs, headers: requestHeaders, body }, (err, res) => {
@@ -228,7 +222,6 @@ const fastifyReplyFrom = fp(function from (fastify, opts, next) {
     // actually destroy those sockets
     setImmediate(next)
   })
-
   next()
 }, {
   fastify: '4.x',
diff --git a/test/retry-with-a-custom-handler.test.js b/test/retry-with-a-custom-handler.test.js
@@ -6,10 +6,11 @@ const From = require('..')
 const http = require('node:http')
 const got = require('got')
 
-function serverWithCustomError (stopAfter, statusCodeToFailOn) {
+function serverWithCustomError (stopAfter, statusCodeToFailOn, closeSocket) {
   let requestCount = 0
   return http.createServer((req, res) => {
     if (requestCount++ < stopAfter) {
+      if (closeSocket) req.socket.end()
       res.statusCode = statusCodeToFailOn
       res.setHeader('Content-Type', 'text/plain')
       return res.end('This Service is Unavailable')
@@ -21,8 +22,9 @@ function serverWithCustomError (stopAfter, statusCodeToFailOn) {
   })
 }
 
-async function setupServer (t, fromOptions = {}, statusCodeToFailOn = 500, stopAfter = 4) {
-  const target = serverWithCustomError(stopAfter, statusCodeToFailOn)
+async function setupServer (t, fromOptions = {}, statusCodeToFailOn = 500, stopAfter = 4, closeSocket = false) {
+  const target = serverWithCustomError(stopAfter, statusCodeToFailOn, closeSocket)
+
   await target.listen({ port: 0 })
   t.teardown(target.close.bind(target))
 
@@ -48,7 +50,7 @@ test('a 500 status code with no custom handler should fail', async (t) => {
 
   let errorMessage
   try {
-    await got.get(`http://localhost:${instance.server.address().port}`, { retry: 0 })
+    await got.get(`http://localhost:${instance.server.address().port}`, { retry: 3 })
   } catch (error) {
     errorMessage = error.message
   }
@@ -57,63 +59,103 @@ test('a 500 status code with no custom handler should fail', async (t) => {
 })
 
 test("a server 500's with a custom handler and should revive", async (t) => {
-  const customRetryLogic = (req, res, getDefaultDelay) => {
+  const customRetryLogic = ({ req, res, err, attempt, getDefaultDelay }) => {
     const defaultDelay = getDefaultDelay()
     if (defaultDelay) return defaultDelay
 
     if (res && res.statusCode === 500 && req.method === 'GET') {
-      return 300
+      return 0.1
     }
     return null
   }
 
-  const { instance } = await setupServer(t, { customRetry: { handler: customRetryLogic, retries: 10 } })
+  const { instance } = await setupServer(t, { retryDelay: customRetryLogic })
 
-  const res = await got.get(`http://localhost:${instance.server.address().port}`, { retry: 0 })
+  const res = await got.get(`http://localhost:${instance.server.address().port}`, { retry: 5 })
 
   t.equal(res.headers['content-type'], 'text/plain')
   t.equal(res.statusCode, 205)
   t.equal(res.body.toString(), 'Hello World 5!')
 })
 
-test('custom retry does not invoke the default delay causing a 503', async (t) => {
-  // the key here is our customRetryHandler doesn't register the deefault handler and as a result it doesn't work
-  const customRetryLogic = (req, res, getDefaultDelay) => {
+test('custom retry does not invoke the default delay causing a 501', async (t) => {
+  // the key here is our retryDelay doesn't register the deefault handler and as a result it doesn't work
+  const customRetryLogic = ({ req, res, err, attempt, getDefaultDelay }) => {
     if (res && res.statusCode === 500 && req.method === 'GET') {
-      return 300
+      return 0
     }
     return null
   }
 
-  const { instance } = await setupServer(t, { customRetry: { handler: customRetryLogic, retries: 10 } }, 503)
+  const { instance } = await setupServer(t, { retryDelay: customRetryLogic }, 501)
 
   let errorMessage
   try {
-    await got.get(`http://localhost:${instance.server.address().port}`, { retry: 0 })
+    await got.get(`http://localhost:${instance.server.address().port}`, { retry: 5 })
   } catch (error) {
     errorMessage = error.message
   }
 
-  t.equal(errorMessage, 'Response code 503 (Service Unavailable)')
+  t.equal(errorMessage, 'Response code 501 (Not Implemented)')
 })
 
 test('custom retry delay functions can invoke the default delay', async (t) => {
-  const customRetryLogic = (req, res, getDefaultDelay) => {
+  const customRetryLogic = ({ req, res, err, attempt, getDefaultDelay }) => {
     // registering the default retry logic for non 500 errors if it occurs
     const defaultDelay = getDefaultDelay()
     if (defaultDelay) return defaultDelay
 
     if (res && res.statusCode === 500 && req.method === 'GET') {
-      return 300
+      return 0.1
+    }
+
+    return null
+  }
+
+  const { instance } = await setupServer(t, { retryDelay: customRetryLogic }, 500)
+
+  const res = await got.get(`http://localhost:${instance.server.address().port}`, { retry: 5 })
+
+  t.equal(res.headers['content-type'], 'text/plain')
+  t.equal(res.statusCode, 205)
+  t.equal(res.body.toString(), 'Hello World 5!')
+})
+
+test('custom retry delay function inspects the err paramater', async (t) => {
+  const customRetryLogic = ({ req, res, err, attempt, getDefaultDelay }) => {
+    if (err && (err.code === 'UND_ERR_SOCKET' || err.code === 'ECONNRESET')) {
+      return 0.1
+    }
+    return null
+  }
+
+  const { instance } = await setupServer(t, { retryDelay: customRetryLogic }, 500, 4, true)
+
+  const res = await got.get(`http://localhost:${instance.server.address().port}`, { retry: 5 })
+
+  t.equal(res.headers['content-type'], 'text/plain')
+  t.equal(res.statusCode, 205)
+  t.equal(res.body.toString(), 'Hello World 5!')
+})
+
+test('we can exceed our retryCount and introspect attempts independently', async (t) => {
+  const attemptCounter = []
+
+  const customRetryLogic = ({ req, res, err, attempt, getDefaultDelay }) => {
+    attemptCounter.push(attempt)
+
+    if (err && (err.code === 'UND_ERR_SOCKET' || err.code === 'ECONNRESET')) {
+      return 0.1
     }
 
     return null
   }
 
-  const { instance } = await setupServer(t, { customRetry: { handler: customRetryLogic, retries: 10 } }, 503)
+  const { instance } = await setupServer(t, { retryDelay: customRetryLogic }, 500, 4, true)
 
-  const res = await got.get(`http://localhost:${instance.server.address().port}`, { retry: 0 })
+  const res = await got.get(`http://localhost:${instance.server.address().port}`, { retry: 5 })
 
+  t.match(attemptCounter, [0, 1, 2, 3, 4])
   t.equal(res.headers['content-type'], 'text/plain')
   t.equal(res.statusCode, 205)
   t.equal(res.body.toString(), 'Hello World 5!')
diff --git a/types/index.d.ts b/types/index.d.ts
@@ -1,33 +1,33 @@
 /// <reference types="node" />
 
 import {
-  FastifyRequest,
+  FastifyPluginCallback,
   FastifyReply,
+  FastifyRequest,
+  HTTPMethods,
   RawReplyDefaultExpression,
   RawServerBase,
   RequestGenericInterface,
-  HTTPMethods,
-  FastifyPluginCallback,
 } from 'fastify';
 
 import {
+  Agent,
+  AgentOptions,
   IncomingHttpHeaders,
   RequestOptions,
-  AgentOptions,
-  Agent,
 } from "http";
 import {
-  RequestOptions as SecureRequestOptions,
-  AgentOptions as SecureAgentOptions,
-  Agent as SecureAgent
-} from "https";
-import {
-  IncomingHttpHeaders as Http2IncomingHttpHeaders,
-  ClientSessionRequestOptions,
   ClientSessionOptions,
+  ClientSessionRequestOptions,
+  IncomingHttpHeaders as Http2IncomingHttpHeaders,
   SecureClientSessionOptions,
 } from "http2";
-import { Pool } from 'undici'
+import {
+  Agent as SecureAgent,
+  AgentOptions as SecureAgentOptions,
+  RequestOptions as SecureRequestOptions
+} from "https";
+import { Pool } from 'undici';
 
 declare module "fastify" {
   interface FastifyReply {
@@ -39,12 +39,21 @@ declare module "fastify" {
 }
 
 type FastifyReplyFrom = FastifyPluginCallback<fastifyReplyFrom.FastifyReplyFromOptions>
-
 declare namespace fastifyReplyFrom {
   type QueryStringFunction = (search: string | undefined, reqUrl: string) => string;
+
+  export type RetryDetails = {
+    err: Error;
+    req: FastifyRequest<RequestGenericInterface, RawServerBase>;
+    res: FastifyReply<RawServerBase>;
+    attempt: number;
+    getDefaultDelay: () => number | null;
+  }
   export interface FastifyReplyFromHooks {
     queryString?: { [key: string]: unknown } | QueryStringFunction;
     contentType?: string;
+    retryDelay?: (details: RetryDetails) => {} | null;
+    retriesCount?: number;
     onResponse?: (
       request: FastifyRequest<RequestGenericInterface, RawServerBase>,
       reply: FastifyReply<RawServerBase>,
@@ -99,7 +108,7 @@ declare namespace fastifyReplyFrom {
   }
 
   export const fastifyReplyFrom: FastifyReplyFrom
-  export { fastifyReplyFrom as default }
+  export { fastifyReplyFrom as default };
 }
 
 declare function fastifyReplyFrom(...params: Parameters<FastifyReplyFrom>): ReturnType<FastifyReplyFrom>
diff --git a/types/index.test-d.ts b/types/index.test-d.ts
@@ -91,6 +91,15 @@ async function main() {
   instance.get("/http2", (request, reply) => {
       reply.from("/", {
           method: "POST",
+          retryDelay: ({err, req, res, attempt, getDefaultDelay}) => {
+              const defaultDelay = getDefaultDelay();
+              if (defaultDelay) return defaultDelay;
+
+              if (res && res.statusCode === 500 && req.method === "GET") {
+                return 300;
+              }
+              return null;
+            },
           rewriteHeaders(headers, req) {
               return headers;
           },
