Cannot connect RDS Database to a Lambda Function (Using serverless framework)

Question

I want to connect my RDS Database table with my lambda function, for this, I have created a lambda function and used knex.js and postgres database in rds, I got the knex object, but I cannot work with any query.

To give some more information about the services,

RDS database server security group can be access from anywhere
I have given the vpc in the serverless.yml file in the function.
Region of both lambda and rds are different, but not sure whether it is the problem.

My serverless function

note: this knex code is working when I tried this separately.

module.exports.storeTransaction = async (event) => {  
  ...  
  knex('Transactions')
  .select('*')
  .then(response => {
    console.log('response is ');
    console.log(response);
  })
  ...
};

Serverless.yml file

service: <service-name>

provider:
  name: aws
  runtime: nodejs8.10
  stage: dev
  region: us-east-1

package:
  exclude:
    - node_modules/**
plugins:
  - serverless-plugin-include-dependencies

functions:
  storeEmail:
    handler: handler.storeTransaction
    vpc:
      securityGroupIds:
        - <security-group-id-of-rds>
      subnetIds:
        - <subnet-id-of-rds>
        - <subnet-id-of-rds>
        ...
      region:
        - us-east-1a
    events:
      - http:
          path: email/store
          method: post
          cors: true

So can you identify my issue on why I can't connect my rds db with lambda function, and let me know what I did wrong or what is missing.

Lorenzo Micheli · Accepted Answer · 2019-05-03 12:59:10Z

1

I think the problem is that RDS and Lambda are in different regions, which means they are also in different VPCs, as a VPC cannot span across multiple regions. Although you can enable Inter VPC Peering (https://aws.amazon.com/vpc/faqs/#Peering_Connections).

Consider that when you deploy a lambda function in a VPC, it won't have internet access as long as you don't attach a NAT Gateway to that VPC/subnet.

If the RDS is open to the world (and does it really need to be??), you can try to deploy in the same region (without a VPC) and verify if that works.

answered May 3, 2019 at 12:59

Lorenzo Micheli

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1 Comment

gokublack Over a year ago

I removed the vpc for my lambda and it's working fine, Thank you.

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