Error: connect ETIMEDOUT (while connecting lambda to RDS)

[kashifaliquazi]

Hello Everyone,

We are using this plugin to connect the Lambda function to the RDS(Arora MySQL). Both Lambda function and RDS are in the Same VPC and in DB's security group inbound traffic is allowed from the whole VPC CIDR.

Some of the time the Lambda is getting timed out with the Below error, Most of the blogs say it is a network topology issue but Lambda is able to access DB most of the time. we face this issue only 2% of the time but it is still impacting the users.

we got the connection some of the times even after this error after retrying (Plugin internal retry mechanism) and some of the times the lambda times out after 2-3 retries.

Here is the code

` let db_config = {};
db_config.host =;
db_config.user =;
db_config.password =;
db_config.connectionLimit = 2;
db_config.multipleStatements = true;

let mysqlconnpool = require('serverless-mysql')({backoff:'decorrelated',base:5,cap:200,config:db_config,
onError:(err)=>{
console.log("mysqlconnpool_onError",err)
},
onConnectError:(err)=>{
console.log("mysqlconnpool_onConnectError",err)
},
onConnect:()=>{
console.log("mysqlconnpool_connected")
}});
module.exports = mysqlconnpool; `

let QueryResults = await mysqlconnpool.query(query); await mysqlconnpool.quit();

Here is the error we are getting:

Error: connect ETIMEDOUT
at Connection._handleConnectTimeout (/opt/node_modules/mysql/lib/Connection.js:409:13)
at Object.onceWrapper (events.js:420:28)
at Socket.emit (events.js:314:20)
at Socket.EventEmitter.emit (domain.js:483:12)
at Socket._onTimeout (net.js:483:8)
at listOnTimeout (internal/timers.js:554:17)
at processTimers (internal/timers.js:497:7)
--------------------
at Protocol._enqueue (/opt/node_modules/mysql/lib/protocol/Protocol.js:144:48)
at Protocol.handshake (/opt/node_modules/mysql/lib/protocol/Protocol.js:51:23)
at Connection.connect (/opt/node_modules/mysql/lib/Connection.js:116:18)
at /opt/node_modules/serverless-mysql/index.js:99:16
at new Promise ()
at _connect (/opt/node_modules/serverless-mysql/index.js:93:14)
at connect (/opt/node_modules/serverless-mysql/index.js:68:13)
at /opt/node_modules/serverless-mysql/index.js:77:39
at async connect (/opt/node_modules/serverless-mysql/index.js:77:9)
at async Object.query (/opt/node_modules/serverless-mysql/index.js:182:5) {
errorno: 'ETIMEDOUT',
code: 'ETIMEDOUT',
syscall: 'connect',
fatal: true
}

Any help would be really appreciated.
Thanks in Advance.