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How to make Lambda connect to DocumentDB

0

I made a lambda function that needs to connect to my DocumentDB Cluster.

I created a security group for lambda to allow outbound 0.0.0.0/0. Then, I edited the VPC settings selecting my default VPC, 2 subnets, and the above security group. Note that the subnets are both public.

Then I modified the DocumentDB security group to allow inbound on 27017 from the lambda security group.

Still I am getting a timeout.

I read somewhere that the subnets need to be private but I only have public subnets, should I create 2 new private ones for this purpose only?

Any other useful suggestion?

thanks M

Topics
Networking & Content DeliveryServerlessComputeAWS Well-Architected Framework
Tags
Amazon VPCAWS LambdaSecuritySecurity Group
Language
English
rePost-User-3116220
asked a year ago1696 views
1 Answer
0

Hello,

  • Is the DocumentDB in the same default VPC?
  • I assume you didn't touch the NACLs or the default route tables?
  • Normally you should have connectivity between all subnets of a VPC by default. So it doesn't matter if the subnets are public or not (for prod, it is highly recommended to use private subnets for obvious security reasons).
  • If you don't find the issue, maybe you could try to connect with an EC2 instance by following this guide: https://docs.aws.amazon.com/documentdb/latest/developerguide/connect-ec2.html
AWS
Vincent
answered a year ago
  • rePost-User-3116220
    a year ago

    Hello Vincent,

    DocumentDB is in the same VPC as lambda and my EC2s.

    I didn't touch NACLs or route tables, note that EC2s and ELB and ASG were made using Elastic Beanstalk.

    I am already able to connect to DocumentDB from my EC2s.

    DocumentDB is in a public subnet, should I move it to a private one? I don't remember I saw this option when I created the cluster.

    Thanks for your help.

  • Vincent
    a year ago

    Is your Lambda launched in the same subnet as your EC2 and using the same security groups? Does your Lambda have the right IAM permissions?

  • rePost-User-3116220
    a year ago

    Update: I just find out that I can connect to DocumentDB if my lambda is both in a public or private subnet. It just need to be in a subnet. Does that means that Doc umentDB is in a public subnet too? Do you think this configuration is secure?

    thanks

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