Merge d71fb88 into 6f5de1f

README.md

@@ -196,6 +196,8 @@ On which methods should the connection be retried in case of socket hang up.
 
 By default: `['GET', 'HEAD', 'OPTIONS', 'TRACE' ]`
 
+This plugin will always retry on 503 errors, _unless_ `retryMethods` does not contain `GET`.
+
 ---
 
 ### `reply.from(source, [opts])`

index.js

@@ -118,9 +118,8 @@ module.exports = fp(function from (fastify, opts, next) {
     const requestHeaders = rewriteRequestHeaders(req, headers)
     const contentLength = requestHeaders['content-length']
     let requestImpl
-
-    if (retriesCount && retryMethods.has(req.method) && !contentLength) {
-      requestImpl = createRequestRetry(request, this, retriesCount, retryOnError)
+    if (retryMethods.has(req.method) && !contentLength) {
+      requestImpl = createRequestRetry(request, this, retriesCount, retryOnError, 503)
     } else {
       requestImpl = request
     }
@@ -213,25 +212,36 @@ function isFastifyMultipartRegistered (fastify) {
   return fastify.hasContentTypeParser('multipart') && fastify.hasRequestDecorator('multipart')
 }
 
-function createRequestRetry (requestImpl, reply, retriesCount, retryOnError) {
+function createRequestRetry (requestImpl, reply, retriesCount, retryOnError, retryOnCode = 503) {
   function requestRetry (req, cb) {
     let retries = 0
 
     function run () {
       requestImpl(req, function (err, res) {
-        if (err && !reply.sent && retriesCount > retries) {
-          if (err.code === retryOnError) {
-            retries += 1
+        // Magic number, so why not 42? We might want to make this configurable.
+        let retryAfter = 42 * Math.random() * (retries + 1)
 
-            run()
-            return
-          }
+        if (res && res.headers['retry-after']) {
+          retryAfter = res.headers['retry-after']
         }
 
+        if (!reply.sent) {
+          // always retry on 503 errors
+          if (res && res.statusCode === retryOnCode && req.method === 'GET') {
+            return retry(retryAfter)
+          } else if (retriesCount > retries && err && err.code === retryOnError) {
+            return retry(retryAfter)
+          }
+        }
         cb(err, res)
       })
     }
 
+    function retry (after) {
+      retries += 1
+      setTimeout(run, after)
+    }
+
     run()
   }
 

test/retry-on-503.js

@@ -0,0 +1,49 @@
+'use strict'
+
+const t = require('tap')
+const Fastify = require('fastify')
+const From = require('..')
+const http = require('http')
+const get = require('simple-get').concat
+
+const instance = Fastify()
+
+t.plan(6)
+t.teardown(instance.close.bind(instance))
+let requestCount = 0
+const target = http.createServer((req, res) => {
+  if (requestCount++ === 0) {
+    res.statusCode = 503
+    res.setHeader('Content-Type', 'text/plain')
+    res.setHeader('Retry-After', 1000)
+    return res.end('This Service Unavailable')
+  }
+  res.statusCode = 205
+  res.setHeader('Content-Type', 'text/plain')
+  return res.end('Hello World Twice!')
+})
+
+instance.get('/', (request, reply) => {
+  reply.from()
+})
+
+t.teardown(target.close.bind(target))
+
+target.listen(0, (err) => {
+  t.error(err)
+
+  instance.register(From, {
+    base: `http://localhost:${target.address().port}`
+  })
+
+  instance.listen(0, (err) => {
+    t.error(err)
+
+    get(`http://localhost:${instance.server.address().port}`, (err, res, data) => {
+      t.error(err)
+      t.equal(res.headers['content-type'], 'text/plain')
+      t.equal(res.statusCode, 205)
+      t.equal(data.toString(), 'Hello World Twice!')
+    })
+  })
+})