Node Codis

Node-codis is a codis client running on nodejs, Used to connect to redis cluster services.

Use the node-zookeeper-client library for service discovery.

Use the redis library to connect to the codis proxy service. The ioredis is supported as well.

中文说明

Getting started

Installation

npm i node-codis -S

Usage

const { NodeCodis } = require('node-codis')

const nodeCodis = new NodeCodis({
  zkServers: '127.0.0.1:6701, 127.0.0.1:6702',
  zkCodisProxyDir: '/zk/codis/db_test_node/proxy',
  codisPassword: 'your_codis_password'
})

nodeCodis.on('connected', (err, client) => {
  if (err) {
    console.log(err)
    return
  }

  // Expires after 100 seconds
  client.SETEX('node-codis:test', 100, 'hello world', NodeCodis.print)
  client.GET('node-codis:test', (err, data) => {
    console.log(data) // hello world
  })
})

ioredis

Codis instance with ioredis can be created by NodeIOCodis.

const Codis = require('node-codis')
const nodeCodis = new Codis.NodeIOCodis({
  // ...
})

nodeCodis.on('connected',
/**
 * @param {Codis.CodisIOClient} client
 */
(err, client) => {
  // ...
})

Please NOTE that NodeIOCodis doesn't have a print method like NodeCodis!

Documentation

Constructor Options

zkServers string required

Comma separated host:port pairs, each represents a ZooKeeper server. You can optionally append a chroot path, then the client would be rooted at the given path. e.g.

'localhost:3000,localhost:3001,localhost:3002'
'localhost:2181,localhost:2182/test'

zkCodisProxyDir string required

Node path of codis-proxy on zookeeper. NodeCodis will establish a connection with all codis-proxy in this directory, and then randomly select one as the client. link this:

/zk/codis/db_test_node/proxy

In the codis2.x, it is usually located at /zk/codis/db_${product_name}/proxy

In the codis3.x, If the server codis-proxy is configured as jodis_compatible = false, it is usually located at /jodis/${product_name}/proxy

codisPassword string optional

Login password for codis-proxy.

zkClientOpts object optional

An object to set the zookeeper client options. Currently available options are:

• sessionTimeout Session timeout in milliseconds, defaults to 30 seconds.

• spinDelay The delay (in milliseconds) between each connection attempts.

• retries The number of retry attempts for connection loss exception.

Defaults options:

{
    sessionTimeout: 30000,
    spinDelay: 1000,
    retries: 1
}

For example:

const nodeCodis = new NodeCodis({
  zkServers: '127.0.0.1:6701, 127.0.0.1:6702',
  zkCodisProxyDir: '/zk/codis/db_test_node/proxy',
  codisPassword: 'your_codis_password',
  zkClientOpts: {
    sessionTimeout: 10000
  }
})

redisClientOpts object optional

We use redis to connect to the codis-proxy service, so you can pass in these parameters when redis creates the client.

Reference here https://github.com/NodeRedis/node_redis#rediscreateclient

log boolean | Function

Whether to enable the log, default open, use the debug library. The printed log looks like this:

node-codis Connect to codis at proxy:e203bf77d1c7b3e2c132984f14827c04 @192.168.3.62:19201 +0ms

node-codis Connect to codis at proxy:40297cde8c3453714459ab1c452c6c56 @192.168.3.72:19201 +7ms

You can also set up a custom logger, like this:

const nodeCodis = new NodeCodis({
  zkServers: '127.0.0.1:6701, 127.0.0.1:6702',
  zkCodisProxyDir: '/zk/codis/db_test_node/proxy',
  codisPassword: 'your_codis_password',
  log: console.log
})

You can pass false to close log.

proxyAddrKey string optional

Proxy address field. Usually when the codis-proxy is registered to zk, the field of the proxy address is called addr. If not, you can pass in a custom field. link this:

const nodeCodis = new NodeCodis({
  zkServers: '127.0.0.1:6701, 127.0.0.1:6702',
  zkCodisProxyDir: '/zk/codis/db_test_node/proxy',
  codisPassword: 'your_codis_password',
  proxyAddrKey: 'proxy_addr'
})

---

Property

codisClientPool

Return all connected codis client. link this:

const nodeCodis = new NodeCodis({
  zkServers: '127.0.0.1:6701, 127.0.0.1:6702',
  zkCodisProxyDir: '/zk/codis/db_test_node/proxy',
  codisPassword: 'your_codis_password'
})

console.log(nodeCodis.codisClientPool)

---

Event

connected

When all codis-proxy are connected for the first time, the connect event is fired and a connected codis client is randomly selected as the argument to the callback function. link this:

const nodeCodis = new NodeCodis({
  zkServers: '127.0.0.1:6701, 127.0.0.1:6702',
  zkCodisProxyDir: '/zk/codis/db_test_node/proxy',
  codisPassword: 'your_codis_password'
})

nodeCodis.on('connected', (err, client) => {
  if (err) {
    console.log(err)
    return
  }

  // Expires after 100 seconds
  client.SETEX('node-codis:test', 100, 'hello world', NodeCodis.print)
  client.GET('node-codis:test', (err, data) => {
    console.log(data) // hello world
  })
})

reconnected

When the zookeeper node of codis changes, the codis-proxy is reconnected internally, and the reconnected event is triggered, and a random connected codis client is passed to the callback function. link this:

const nodeCodis = new NodeCodis({
  zkServers: '127.0.0.1:6701, 127.0.0.1:6702',
  zkCodisProxyDir: '/zk/codis/db_test_node/proxy',
  codisPassword: 'your_codis_password'
})

nodeCodis.on('reconnected', (err, client) => {
  if (err) {
    console.log(err)
    return
  }

  console.log(client)
})

---

Static methods

getRandomClient(clientsMap: CodisClientPool)

Randomly get a connected codis client, if the client pool is empty, return null. You can use this method in some framework middleware to achieve load balancing. link this:

// app.js
var createError = require('http-errors');
var express = require('express');
var path = require('path');
var cookieParser = require('cookie-parser');
var logger = require('morgan');
var { NodeCodis } = require('node-codis')

var indexRouter = require('./routes/index');

var app = express();

app.use(logger('dev'));
app.use(express.json());
app.use(express.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));

const nodeCodis = new NodeCodis({
  zkServers: '127.0.0.1:6701, 127.0.0.1:6702',
  zkCodisProxyDir: '/zk/codis/db_test_node/proxy',
  codisPassword: 'your_codis_password'
})

nodeCodis.on('connected', (err, client) => {
  if (err) {
    console.log(err)
    return
  }
  app.set('codisClientPool', nodeCodis.codisClientPool)
})

app.use(function(req, res, next) {
  var codisClientPool = req.app.get('codisClientPool')
  req.codisClientPool = NodeCodis.getRandomClient(codisClientPool)
  next()
})

app.use('/', indexRouter);

app.use(function (req, res, next) {
  next(createError(404));
});

app.use(function (err, req, res, next) {
  res.locals.message = err.message;
  res.locals.error = req.app.get('env') === 'development' ? err : {};

  res.status(err.status || 500);
  res.render('error');
});

module.exports = app;

// routes/index.js
var express = require('express');
var router = express.Router();

router.get('/test', function (req, res) {
  const codisClient = req.codisClient
  if (codisClient) {
    console.log(codisClient.address)
  }
})

module.exports = router;

When you always request localhost:3000/test, printed as follows:

192.168.3.72:19201
GET /test - - ms - -
192.168.3.72:19201
GET /test - - ms - -
192.168.3.62:19201
GET /test - - ms - -
192.168.3.62:19201
GET /test - - ms - -
192.168.3.72:19201
GET /test - - ms - -
192.168.3.62:19201
GET /test - - ms - -
192.168.3.62:19201
GET /test - - ms - -
192.168.3.62:19201
GET /test - - ms - -
192.168.3.72:19201
GET /test - - ms - -
192.168.3.62:19201

Licence

NodeCodis is licensed under the MIT License - see the LICENSE file for details.