ETIMEDOUT connecting to MySql from Lambda - mysql

Question

I am trying to connect to a MySql RDS instance from a Lambda function and getting an ETIMEDOUT error
The Lambda is not part of a VPC
The RDS instance is available publicly, I can connect to it from my laptop using MySqlWorkbench
The RDS instance's security group has inbound rules configured for all ports and 0.0.0.0/0
The Lambda's execution role has many policies (probably too many) including RDSFullAccess, LambdaVPCAccessExecutionRole, ec2:*, even AdministratorAccess!)
Again, the code executes locally, connects to and queries the RDS instance just fine. Executing the same code in Lambda throws the ETIMEDOUT error
Similar posts are resolved by adding the Lambda to the RDS instance's VPC, or by configuring the inbound rules on the database's security group. Nothing seems to work.
Since I can connect to the database from my laptop just fine, my hunch is that it's a problem with the Lambda
Are there additional policies I should attach to the Lambda's execution role?
Is there any other reason the Lambda would time out connecting to a publicly available database?
Additional info:
The Lambda is not running in a VPC. It runs on Node and connects to MySql using the mysql package v2.18.1 and is deployed using Serverless with the following config:
foo:
handler: functions/handlers.foo
timeout: 20
events:
- http:
path: /path/{pathParameter}/foo
method: get
cors: true
caching:
enabled: true
ttlInSeconds: 3600
cacheKeyParameters:
- name: request.path.pathParameter
In the Lambda I try connecting with this function (which, again, works fine when I execute the function on my laptop):
function openDbConnection() {
let connection = mysql.createConnection({
host: 'db-name.cgwxrjuo6oyd.us-east-1.rds.amazonaws.com',
user: process.env.DB_USER,
password: process.env.DB_PASS,
database: 'db-name'
});
try {
connection.connect(function(err) {
console.log("Database is ", connection.state)
if (err) {
return console.error('error: ' + err.message);
}
console.log('Connected to the MySQL server.');
});
} catch (error) {
console.log("Database is ", connection.state)
console.log("Error connecting to MySql: ", error);
}
return connection;
}
The database username and password are retrieved from environment variables that are published to the Lambda with Serverless using a .env.yml file:
provider:
name: aws
runtime: nodejs12.x
lambdaHashingVersion: '20201221'
environment: ${file(.env.yml):}
Below are the Cloudwatch logs for a single execution, which I'm having trouble making sense of. Entries appear out of sequence:
| timestamp | message |
|---------------|----------------------------------------------------------------------------------------------------------------------------------------------------------|
| 1626209636788 | START RequestId: e3e3ceb7-bb55-4c3e-8392-38e08401f679 Version: $LATEST |
| 1626209636791 | 2021-07-13T20:53:56.790Z adfc1cd5-e4be-40b7-970c-d38acabeb199 INFO Database is disconnected |
| 1626209636791 | 2021-07-13T20:53:56.791Z adfc1cd5-e4be-40b7-970c-d38acabeb199 ERROR error: connect ETIMEDOUT |
| 1626209636791 | 2021-07-13T20:53:56.791Z adfc1cd5-e4be-40b7-970c-d38acabeb199 INFO An error occured querying MySql: connect ETIMEDOUT |
| 1626209636792 | 2021-07-13T20:53:56.792Z adfc1cd5-e4be-40b7-970c-d38acabeb199 INFO Database is disconnected |
| 1626209636792 | 2021-07-13T20:53:56.792Z adfc1cd5-e4be-40b7-970c-d38acabeb199 ERROR error: Connection lost: The server closed the connection. |
| 1626209636793 | 2021-07-13T20:53:56.792Z adfc1cd5-e4be-40b7-970c-d38acabeb199 INFO An error occured querying MySql: Connection lost: The server closed the connection. | 1626209636803 | END RequestId: e3e3ceb7-bb55-4c3e-8392-38e08401f679 |
| 1626209636803 | REPORT RequestId: e3e3ceb7-bb55-4c3e-8392-38e08401f679 Duration: 9.32 ms Billed Duration: 10 ms Memory Size: 1024 MB Max Memory Used: 79 MB |
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