Allow specifying a singleton Redis instance

Author: jsumners

README.md

@@ -11,7 +11,7 @@ Under the hood the official [redis](https://github.com/NodeRedis/node_redis) cli
 npm i fastify-redis --save
 ```
 ## Usage
-Add it to you project with `register` and you are done!
+Add it to your project with `register` and you are done!
 You can access the *Redis* client via `fastify.redis`.
 
 If needed, you can pass a custom ``driver`` option, such as [ioredis](https://github.com/luin/ioredis). By default the official [redis](https://github.com/NodeRedis/node_redis) client is used.
@@ -47,6 +47,20 @@ fastify.listen(3000, err => {
 })
 ```
 
+You may also supply an existing *Redis* client instance by passing an options
+object with the `client` property set to the instance.
+
+```js
+const fastify = Fastify()
+const redis = require('redis').createClient({host: 'localhost', port: 6379})
+
+fastify.register(fastifyRedis, {client: redis})
+
+// ...
+// ...
+// ...
+```
+
 ## Acknowledgements
 
 This project is kindly sponsored by:

index.js

@@ -4,14 +4,17 @@ const fp = require('fastify-plugin')
 const redis = require('redis')
 
 function fastifyRedis (fastify, options, next) {
-  var client = null
-  try {
-    // if custom redis module, default is redis.
-    const Driver = options.driver
-    delete options.driver
-    client = Driver ? new Driver(options) : redis.createClient(options)
-  } catch (err) {
-    return next(err)
+  var client = options.client || null
+
+  if (!client) {
+    try {
+      // if custom redis module, default is redis.
+      const Driver = options.driver
+      delete options.driver
+      client = Driver ? new Driver(options) : redis.createClient(options)
+    } catch (err) {
+      return next(err)
+    }
   }
 
   fastify

test.js

@@ -110,3 +110,26 @@ test('fastify.redis should be the redis client when use the custom redis driver'
     })
   })
 })
+
+test('fastify.redis should be a singleton', t => {
+  t.plan(5)
+  const fastify = Fastify()
+  const redis = require('redis').createClient({host: 'localhost', port: 6379})
+
+  fastify.register(fastifyRedis, {client: redis})
+
+  fastify.ready(err => {
+    t.error(err)
+    t.is(fastify.redis, redis)
+
+    fastify.redis.set('key', 'value', err => {
+      t.error(err)
+      fastify.redis.get('key', (err, val) => {
+        t.error(err)
+        t.equal(val, 'value')
+
+        fastify.close()
+      })
+    })
+  })
+})