issue to connect to elasticache

[yiwong2001]

Hi,

I am running clustr against an AWS ElastiCache cluster (5.0 version). I have one master node and two slaves. Iam using the cluster configuration endpoint to connect to the cluster.

var client = new RedisClustr({
  servers: [
    {
      host: 'xxxxx.jwkwkt.0001.euw1.cache.amazonaws.com'
    }
  ]
});

It is fine to run write task, but when it run read methods like llen, get, then it hangs there.

client.llen(vkey, function (err, sum) { // it is stopped at this stage
console.log("sum..."+sum);
client.set(key, JSON.stringify(i), 'EX', 60); // it can be run if it is not inside of llen method.
});

I also tried elasticache with cluster enabled to have 3 shards and 3 replica for each. It got same issue to run read method.

Same code works when it is not cluster.

Can you guide me please?

[simontabor]

Hi @yiwong2001, I'm actively using this with AWS ElastiCache v5 and haven't got the same issue as you.

Could you try logging client.connections and send the result?

[wip0]

I tried with configuration endpoint for my cluster (TLS enabled). An error below:
Error: couldn't get client

Here is my code:

const defaultRedisOptions: ClientOpts = {
    retry_strategy: (options: RetryStrategyOptions) => {
        return 50;
    },
    no_ready_check: false,
    enable_offline_queue: true,
};
    const options = {
        servers: {
            host: 'clustercfg.REPLICATION_GROUPID.1swv5v.use1.cache.amazonaws.com',
            port: 6379,
        },
        slotInterval: 1000, // default: none. Interval to repeatedly re-fetch cluster slot configuration
        redisOptions: {
            ...defaultRedisOptions,
            tls: bEncryptInTransit ? {} : null,
        },
        createClient: (port, host) => {
            console.log(`createClient host=${host} port=${port}`);
            return createClient(port, host, {
                ...defaultRedisOptions,
                tls: bEncryptInTransit ? {} : null,
            });
        },
   const redis = new RedisClustr(options);
   redis.on('ready', () => { console.log('REDIS ready'); });
   ...
   promisify(redis.scard).bind(redis)(key); // <--- error here

Here are logs from AWS CloudWatch:

createClient host=clustercfg.REPLICATION_GROUPID.1swv5v.use1.cache.amazonaws.com port=6379
createClient host=REPLICATION_GROUPID-0001-001.REPLICATION_GROUPID.1swv5v.use1.cache.amazonaws.com port=6379
REDIS ready
Error: couldn't get client"

However, if I create redis with node's endpoint directly. It's ok.

    const options = {
        servers: {
            host: 'REPLICATION_GROUPID-0001-001.REPLICATION_GROUPID.1swv5v.use1.cache.amazonaws.com',
            port: 6379,
        },
...

But this does not suite for my case. I need to create it from configuration endpoint.

[wip0]

@simontabor Could you give me an example of your codes, please?

[aravindgopall]

@wip0 @simontabor refer these : gosquared/stash#7 and #37

[simontabor]

Hi @wip0 @aravindgopall, you should be able to avoid this issue when connecting to an ElastiCache replication group by waiting for the fullReady event before running commands. fullReady is emitted when redis-clustr has a healthy connection to all the nodes in the cluster, rather than just the configuration endpoint.

[larryboymi]

If the fullReady event is a requirement, why not add that check to the wrapper?

[aadi99999]

Has this issue fixed ?
I am making a connection to the cluster via hostname.

[bazingarj]

I am facing the same Issue. I can see the nodes IP in the logs , but when i get a keys then it says:

Error: couldn't get client
    at /var/task/node_modules/redis-clustr/src/RedisClustr.js:382:23
    at module.exports.RedisClustr.parseArgs (/var/task/node_modules/redis-clustr/src/RedisClustr.js:362:11)
    at /var/task/node_modules/redis-clustr/src/RedisClustr.js:350:12
    at runCbs (/var/task/node_modules/redis-clustr/src/RedisClustr.js:181:7)
    at Command.callback (/var/task/node_modules/redis-clustr/src/RedisClustr.js:265:7)
    at normal_reply (/var/task/node_modules/redis/index.js:726:21)
    at RedisClient.return_reply (/var/task/node_modules/redis/index.js:824:9)
    at JavascriptRedisParser.returnReply (/var/task/node_modules/redis/index.js:192:18)
    at JavascriptRedisParser.execute (/var/task/node_modules/redis/node_modules/redis-parser/lib/parser.js:574:12)
    at Socket.<anonymous> (/var/task/node_modules/redis/index.js:274:27)

[rmitcoder]

I got this issue as well when upgrading nodejs from v8 to v16. Any idea?

[kaspesla]

I got this and fixed it by doing a short setTimeout to delay before trying to do anything with the cluster.