[feature] custom retry callback

README.md

@@ -14,7 +14,7 @@ npm i @fastify/reply-from
 ```
 
 ## Compatibility with @fastify/multipart
-`@fastify/reply-from` and [`@fastify/multipart`](https://github.com/fastify/fastify-multipart) should not be registered as sibling plugins nor should they be registered in plugins which have a parent-child relationship.<br> The two plugins are incompatible, in the sense that the behavior of `@fastify/reply-from` might not be the expected one when the above-mentioned conditions are not respected.<br> This is due to the fact that `@fastify/multipart` consumes the multipart content by parsing it, hence this content is not forwarded to the target service by `@fastify/reply-from`.<br>
+`@fastify/reply-from` and [`@fastify/multipart`](https://github.com/fastify/fastify-multipart) should not be registered as sibling plugins nor should they be registered in plugins which have a parent-child relationship.`<br>` The two plugins are incompatible, in the sense that the behavior of `@fastify/reply-from` might not be the expected one when the above-mentioned conditions are not respected.`<br>` This is due to the fact that `@fastify/multipart` consumes the multipart content by parsing it, hence this content is not forwarded to the target service by `@fastify/reply-from`.`<br>`
 However, the two plugins may be used within the same fastify instance, at the condition that they belong to disjoint branches of the fastify plugins hierarchy tree.
 
 ## Usage
@@ -115,7 +115,7 @@ proxy.register(require('@fastify/reply-from'), {
 
 #### `http`
 
-Set the `http` option to an Object to use 
+Set the `http` option to an Object to use
 Node's [`http.request`](https://nodejs.org/api/http.html#http_http_request_options_callback)
 will be used if you do not enable [`http2`](#http2). To customize the `request`,
 you can pass in [`agentOptions`](https://nodejs.org/api/http.html#http_new_agent_options) and
@@ -136,6 +136,7 @@ proxy.register(require('@fastify/reply-from'), {
 ```
 
 You can also pass custom HTTP agents. If you pass the agents, then the http.agentOptions will be ignored. To illustrate:
+
 ```js
 proxy.register(require('@fastify/reply-from'), {
   base: 'http://localhost:3001/',
@@ -192,27 +193,27 @@ The number of parsed URLs that will be cached. Default: `100`.
 
 #### `disableCache`
 
-This option will disable the URL caching. 
+This option will disable the URL caching.
 This cache is dedicated to reduce the amount of URL object generation.
 Generating URLs is a main bottleneck of this module, please disable this cache with caution.
 
 #### `contentTypesToEncode`
 
-An array of content types whose response body will be passed through `JSON.stringify()`. 
+An array of content types whose response body will be passed through `JSON.stringify()`.
 This only applies when a custom [`body`](#body) is not passed in. Defaults to:
 
 ```js
-[ 
+[
   'application/json'
 ]
 ```
 
 #### `retryMethods`
 
-On which methods should the connection be retried in case of socket hang up.  
+On which methods should the connection be retried in case of socket hang up.
 **Be aware** that setting here not idempotent method may lead to unexpected results on target.
 
-By default: `['GET', 'HEAD', 'OPTIONS', 'TRACE' ]`
+By default: `['GET', 'HEAD', 'OPTIONS', 'TRACE']`
 
 This plugin will always retry on 503 errors, _unless_ `retryMethods` does not contain `GET`.
 
@@ -221,6 +222,7 @@ This plugin will always retry on 503 errors, _unless_ `retryMethods` does not co
 Enables the possibility to explictly opt-in for global agents.
 
 Usage for undici global agent:
+
 ```js
 import { setGlobalDispatcher, ProxyAgent } from 'undici'
 
@@ -234,11 +236,12 @@ fastify.register(FastifyReplyFrom, {
 ```
 
 Usage for http/https global agent:
+
 ```js
 fastify.register(FastifyReplyFrom, {
   base: 'http://localhost:3001/',
   // http and https is allowed to use http.globalAgent or https.globalAgent
-  globalAgent: true, 
+  globalAgent: true,
   http: {
   }
 })
@@ -263,6 +266,39 @@ This option set the limit on how many times the plugin should retry the request,
 
 By Default: 10
 
+---
+
+### `customRetry`
+
+- `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
+
+Given example
+
+```js
+  const customRetryLogic = (req, res, getDefaultRetry) => {
+    //If this block is not included all non 500 errors will not be retried
+    const defaultDelay = getDefaultDelay();
+    if (defaultDelay) return defaultDelay();
+
+    //Custom retry logic
+    if (res && res.statusCode === 500 && req.method === 'GET') {
+      return 300
+    }
+    return null
+  }
+
+.......
+
+fastify.register(FastifyReplyFrom, {
+  base: 'http://localhost:3001/',
+  customRetry: {handler: customRetryLogic, retries: 10}
+})
+
+```
 
 ---
 
@@ -328,6 +364,7 @@ ContraintStrategies.
 e.g.:
 
 Route grpc-web/http1 and grpc/http2 to different routes with a ContentType-ConstraintStrategy:
+
 ```
 const contentTypeMatchContraintStrategy = {
     // strategy name for referencing in the route handler `constraints` options
@@ -341,36 +378,36 @@ const contentTypeMatchContraintStrategy = {
       }
     },
     // function to get the value of the constraint from each incoming request
-    deriveConstraint: (req: any, ctx: any) => { 
+    deriveConstraint: (req: any, ctx: any) => {
       return req.headers['content-type']
     },
     // optional flag marking if handlers without constraints can match requests that have a value for this constraint
     mustMatchWhenDerived: true
   }
- 
+
   server.addConstraintStrategy(contentTypeMatchContraintStrategy);
 ```
 
 and then 2 different upstreams with different register's:
+
 ```
 // grpc-web / http1
 server.register(fastifyHttpProxy, {
     // Although most browsers send with http2, nodejs cannot handle this http2 request
     // therefore we have to transport to the grpc-web-proxy via http1
     http2: false,
     upstream: 'http://grpc-web-proxy',
-    constraints: { "contentType": "application/grpc-web+proto" }   
+    constraints: { "contentType": "application/grpc-web+proto" }
 });
 
 // grpc / http2
 server.register(fastifyHttpProxy, {
     http2: true,
     upstream: 'http://grpc.server',
-    constraints: { "contentType": "application/grpc+proto" }   
+    constraints: { "contentType": "application/grpc+proto" }
 });
 ```
 
-
 #### `queryString` or `queryString(search, reqUrl)`
 
 Replaces the original querystring of the request with what is specified.
@@ -390,12 +427,12 @@ Setting this option to `null` will strip the body (and `content-type` header) en
 
 #### `method`
 
-Replaces the original request method with what is specified. 
+Replaces the original request method with what is specified.
 
 #### `retriesCount`
 
-How many times it will try to pick another connection on socket hangup (`ECONNRESET` error).  
-Useful when keeping the connection open (KeepAlive).  
+How many times it will try to pick another connection on socket hangup (`ECONNRESET` error).
+Useful when keeping the connection open (KeepAlive).
 This number should be a function of the number of connections and the number of instances of a target.
 
 By default: 0 (disabled)
@@ -407,13 +444,13 @@ already overriding the [`body`](#body).
 
 ### Combining with [@fastify/formbody](https://github.com/fastify/fastify-formbody)
 
-`formbody` expects the body to be returned as a string and not an object. 
+`formbody` expects the body to be returned as a string and not an object.
 Use the [`contentTypesToEncode`](#contentTypesToEncode) option to pass in `['application/x-www-form-urlencoded']`
 
-
 ### HTTP & HTTP2 timeouts
 
 This library has:
+
 - `timeout` for `http` set by default. The default value is 10 seconds (`10000`).
 - `requestTimeout` & `sessionTimeout` for `http2` set by default.
   - The default value for `requestTimeout` is 10 seconds (`10000`).
@@ -426,10 +463,10 @@ will be returned to the client.
 
 * [ ] support overriding the body with a stream
 * [ ] forward the request id to the other peer might require some
-      refactoring because we have to make the `req.id` unique
-      (see [hyperid](https://npm.im/hyperid)).
+  refactoring because we have to make the `req.id` unique
+  (see [hyperid](https://npm.im/hyperid)).
 * [ ] Support origin HTTP2 push
-* [x] benchmarks
+* [X] benchmarks
 
 ## License
 

index.js

@@ -29,8 +29,7 @@ const fastifyReplyFrom = fp(function from (fastify, opts, next) {
   ])
 
   const retryMethods = new Set(opts.retryMethods || [
-    'GET', 'HEAD', 'OPTIONS', 'TRACE'
-  ])
+    'GET', 'HEAD', 'OPTIONS', 'TRACE'])
 
   const cache = opts.disableCache ? undefined : lru(opts.cacheURLs || 100)
   const base = opts.base
@@ -60,6 +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
 
     if (!source) {
       source = req.url
@@ -143,7 +143,35 @@ const fastifyReplyFrom = fp(function from (fastify, opts, next) {
     const contentLength = requestHeaders['content-length']
     let requestImpl
     if (retryMethods.has(method) && !contentLength) {
-      requestImpl = createRequestRetry(request, this, retriesCount, retryOnError, maxRetriesOn503)
+      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)
+          }
+        }
+        return defaultDelay()
+      }
+
+      requestImpl = createRequestRetry(request, this, retryHandler)
     } else {
       requestImpl = request
     }
@@ -251,28 +279,15 @@ function isFastifyMultipartRegistered (fastify) {
   return (fastify.hasContentTypeParser('multipart') || fastify.hasContentTypeParser('multipart/form-data')) && fastify.hasRequestDecorator('multipart')
 }
 
-function createRequestRetry (requestImpl, reply, retriesCount, retryOnError, maxRetriesOn503) {
+function createRequestRetry (requestImpl, reply, retryHandler) {
   function requestRetry (req, cb) {
     let retries = 0
 
     function run () {
       requestImpl(req, function (err, res) {
-        // 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 (!reply.sent) {
-          // always retry on 503 errors
-          if (res && res.statusCode === 503 && req.method === 'GET') {
-            if (retriesCount === 0 && retries < maxRetriesOn503) {
-              // we should stop at some point
-              return retry(retryAfter)
-            }
-          } else if (retriesCount > retries && err && err.code === retryOnError) {
-            return retry(retryAfter)
-          }
+        const retryDelay = retryHandler(req, res, err, retries)
+        if (!reply.sent && retryDelay) {
+          return retry(retryDelay)
         }
         cb(err, res)
       })