feat(cluster): add NAT support

README.md

@@ -29,6 +29,7 @@ used in the world's biggest online commerce company [Alibaba](http://www.alibaba
 0. Support for ES6 types, such as `Map` and `Set`.
 0. Support for GEO commands (Redis 3.2 Unstable).
 0. Sophisticated error handling strategy.
+0. Support for NAT mapping.
 
 # Links
 * [API Documentation](API.md)
@@ -836,6 +837,26 @@ Promise.all(masters.map(function (node) {
 });
 ```
 
+### NAT Mapping
+Sometimes the cluster is hosted within a internal network that can only be accessed via a NAT (Network Address Translation) instance. See [Accessing ElastiCache from outside AWS](https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/accessing-elasticache.html) as an example.
+
+You can specify nat mapping rules via `natMap` option:
+
+```javascript
+const cluster = new Redis.Cluster([{
+  host: '203.0.113.73',
+  port: 30001
+}], {
+  natMap: {
+    '10.0.1.230:30001': {host: '203.0.113.73', port: 30001},
+    '10.0.1.231:30001': {host: '203.0.113.73', port: 30002},
+    '10.0.1.232:30001': {host: '203.0.113.73', port: 30003}
+  }
+})
+```
+
+This option is also useful when the cluster is running inside a Docker container.
+
 ### Transaction and pipeline in Cluster mode
 Almost all features that are supported by `Redis` are also supported by `Redis.Cluster`, e.g. custom commands, transaction and pipeline.
 However there are some differences when using transaction and pipeline in Cluster mode:

lib/cluster/ClusterOptions.ts

@@ -2,6 +2,7 @@ import {NodeRole} from './util'
 import {lookup} from 'dns'
 
 export type DNSLookupFunction = (hostname: string, callback: (err: NodeJS.ErrnoException, address: string, family: number) => void) => void
+export type NatMap = {[key: string]: {host: string, port: number}}
 
 /**
  * Options for Cluster constructor
@@ -116,6 +117,7 @@ export interface IClusterOptions {
    * @default require('dns').lookup
    */
   dnsLookup?: DNSLookupFunction
+  natMap?: NatMap
 }
 
 export const DEFAULT_CLUSTER_OPTIONS: IClusterOptions = {

lib/cluster/index.ts

@@ -2,7 +2,7 @@ import {EventEmitter} from 'events'
 import ClusterAllFailedError from '../errors/ClusterAllFailedError'
 import {defaults, noop} from '../utils/lodash'
 import ConnectionPool from './ConnectionPool'
-import {NodeKey, IRedisOptions, normalizeNodeOptions, NodeRole, getUniqueHostnamesFromOptions} from './util'
+import {NodeKey, IRedisOptions, normalizeNodeOptions, NodeRole, getUniqueHostnamesFromOptions, nodeKeyToRedisOptions} from './util'
 import ClusterSubscriber from './ClusterSubscriber'
 import DelayQueue from './DelayQueue'
 import ScanStream from '../ScanStream'
@@ -416,6 +416,18 @@ class Cluster extends EventEmitter {
     }
   }
 
+  natMapper(nodeKey: NodeKey | IRedisOptions): IRedisOptions {
+    if (this.options.natMap && typeof this.options.natMap === 'object') {
+      const key = typeof nodeKey === 'string' ? nodeKey : `${nodeKey.host}:${nodeKey.port}`
+      const mapped = this.options.natMap[key]
+      if (mapped) {
+        debug('NAT mapping %s -> %O', key, mapped)
+        return mapped
+      }
+    }
+    return typeof nodeKey === 'string' ? nodeKeyToRedisOptions(nodeKey) : nodeKey
+  }
+
   sendCommand(command, stream, node) {
     if (this.status === 'wait') {
       this.connect().catch(noop)
@@ -449,16 +461,15 @@ class Cluster extends EventEmitter {
             } else {
               _this.slots[slot] = [key]
             }
-            const splitKey = key.split(':')
-            _this.connectionPool.findOrCreate({host: splitKey[0], port: Number(splitKey[1])})
+            _this.connectionPool.findOrCreate(_this.natMapper(key))
             tryConnection()
             _this.refreshSlotsCache()
           },
           ask: function (slot, key) {
             debug('command %s is required to ask %s:%s', command.name, key)
-            const splitKey = key.split(':')
-            _this.connectionPool.findOrCreate({host: splitKey[0], port: Number(splitKey[1])})
-            tryConnection(false, key)
+            const mapped = _this.natMapper(key)
+            _this.connectionPool.findOrCreate(mapped)
+            tryConnection(false, `${mapped.host}:${mapped.port}`)
           },
           tryagain: partialTry,
           clusterDown: partialTry,
@@ -610,7 +621,7 @@ class Cluster extends EventEmitter {
 
         const keys = []
         for (let j = 2; j < items.length; j++) {
-          items[j] = {host: items[j][0], port: items[j][1]}
+          items[j] = this.natMapper({host: items[j][0], port: items[j][1]})
           items[j].readOnly = j !== 2
           nodes.push(items[j])
           keys.push(items[j].host + ':' + items[j].port)

lib/cluster/util.ts

@@ -18,6 +18,17 @@ export function getNodeKey(node: IRedisOptions): NodeKey {
   return node.host + ':' + node.port
 }
 
+export function nodeKeyToRedisOptions(nodeKey: NodeKey): IRedisOptions {
+  const portIndex = nodeKey.lastIndexOf(':')
+  if (portIndex === -1) {
+    throw new Error(`Invalid node key ${nodeKey}`)
+  }
+  return {
+    host: nodeKey.slice(0, portIndex),
+    port: Number(nodeKey.slice(portIndex + 1))
+  }
+}
+
 export function normalizeNodeOptions(nodes: Array<string | number | object>): IRedisOptions[] {
   return nodes.map((node) => {
     const options: any = {}

test/functional/cluster/nat.js

@@ -0,0 +1,127 @@
+const calculateSlot = require('cluster-key-slot')
+
+describe('NAT', () => {
+  it('works for normal case', (done) => {
+    const slotTable = [
+      [0, 1, ['192.168.1.1', 30001]],
+      [2, 16383, ['192.168.1.2', 30001]]
+    ]
+
+    let cluster
+    new MockServer(30001, null, slotTable)
+    new MockServer(30002, ([command, arg]) => {
+      if (command === 'get' && arg === 'foo') {
+        cluster.disconnect()
+        done()
+      }
+    }, slotTable)
+
+    cluster = new Redis.Cluster([{
+      host: '127.0.0.1',
+      port: 30001
+    }], {
+      natMap: {
+        '192.168.1.1:30001': {host: '127.0.0.1', port: 30001},
+        '192.168.1.2:30001': {host: '127.0.0.1', port: 30002}
+      }
+    })
+
+    cluster.get('foo')
+  })
+
+  it('works if natMap does not match all the cases', (done) => {
+    const slotTable = [
+      [0, 1, ['192.168.1.1', 30001]],
+      [2, 16383, ['127.0.0.1', 30002]]
+    ]
+
+    let cluster
+    new MockServer(30001, null, slotTable)
+    new MockServer(30002, ([command, arg]) => {
+      if (command === 'get' && arg === 'foo') {
+        cluster.disconnect()
+        done()
+      }
+    }, slotTable)
+
+    cluster = new Redis.Cluster([{
+      host: '127.0.0.1',
+      port: 30001
+    }], {
+      natMap: {
+        '192.168.1.1:30001': {host: '127.0.0.1', port: 30001}
+      }
+    })
+
+    cluster.get('foo')
+  })
+
+  it('works for moved', (done) => {
+    const slotTable = [
+      [0, 16383, ['192.168.1.1', 30001]]
+    ]
+
+    let cluster
+    new MockServer(30001, ([command, arg]) => {
+      if (command === 'get' && arg === 'foo') {
+        return new Error('MOVED ' + calculateSlot('foo') + ' 192.168.1.2:30001');
+      }
+    }, slotTable)
+    new MockServer(30002, ([command, arg]) => {
+      if (command === 'get' && arg === 'foo') {
+        cluster.disconnect()
+        done()
+      }
+    }, slotTable)
+
+    cluster = new Redis.Cluster([{
+      host: '127.0.0.1',
+      port: 30001
+    }], {
+      natMap: {
+        '192.168.1.1:30001': {host: '127.0.0.1', port: 30001},
+        '192.168.1.2:30001': {host: '127.0.0.1', port: 30002}
+      }
+    })
+
+    cluster.get('foo')
+  })
+
+  it('works for ask', (done) => {
+    const slotTable = [
+      [0, 16383, ['192.168.1.1', 30001]]
+    ]
+
+    let cluster
+    let asked = false
+    new MockServer(30001, ([command, arg]) => {
+      if (command === 'get' && arg === 'foo') {
+        return new Error('ASK ' + calculateSlot('foo') + ' 192.168.1.2:30001');
+      }
+    }, slotTable)
+    new MockServer(30002, ([command, arg]) => {
+      if (command === 'asking') {
+        asked = true
+      }
+      if (command === 'get' && arg === 'foo') {
+        if (!asked) {
+          throw new Error('expected asked to be true')
+        }
+        cluster.disconnect()
+        done()
+      }
+    }, slotTable)
+
+    cluster = new Redis.Cluster([{
+      host: '127.0.0.1',
+      port: 30001
+    }], {
+      natMap: {
+        '192.168.1.1:30001': {host: '127.0.0.1', port: 30001},
+        '192.168.1.2:30001': {host: '127.0.0.1', port: 30002}
+      }
+    })
+
+    cluster.get('foo')
+  })
+})

test/unit/cluster.js

@@ -1,6 +1,7 @@
 'use strict';
 
 var Cluster = require('../../lib/cluster').default;
+const {nodeKeyToRedisOptions} = require('../../lib/cluster/util')
 
 describe('cluster', function () {
   beforeEach(function () {
@@ -36,3 +37,12 @@ describe('cluster', function () {
     });
   });
 });
+
+describe('nodeKeyToRedisOptions()', () => {
+  it('returns correct result', () => {
+    expect(nodeKeyToRedisOptions('127.0.0.1:6379')).to.eql({port: 6379, host: '127.0.0.1'})
+    expect(nodeKeyToRedisOptions('192.168.1.1:30001')).to.eql({port: 30001, host: '192.168.1.1'})
+    expect(nodeKeyToRedisOptions('::0:6379')).to.eql({port: 6379, host: '::0'})
+    expect(nodeKeyToRedisOptions('0:0:6379')).to.eql({port: 6379, host: '0:0'})
+  })
+})