Setting Up VPC Peering for AWS Cloud9 and EC2: A Step-by-Step Guide

When working with AWS Cloud9 and EC2 instances that reside in different Virtual Private Clouds (VPCs), you might encounter connectivity issues due to the isolated nature of VPCs. One solution to this problem is to set up a VPC peering connection. In this guide, we’ll walk you through the process of establishing a VPC peering connection between the VPC of your Cloud9 environment and that of your EC2 instance. If you’re facing hostname resolution issues, our article on Troubleshooting Cloud9: Resolving Hostname Issues with EC2 Instances provides a deep dive into potential solutions.

1. Check Existing VPC Peering Connections

  • Navigate to the VPC Dashboard in the AWS Management Console.
  • In the left navigation pane, click on “Peering Connections.”
  • Check if there’s an existing peering connection between the VPC of your Cloud9 environment and the VPC of your EC2 instance.

2. Create a VPC Peering Connection

If there’s no existing peering connection:

  • Click on “Create Peering Connection.”
  • Provide a name for the connection.
  • Select the VPC of your Cloud9 environment for the “Requester VPC” and the VPC of your EC2 instance for the “Accepter VPC.”
  • Click on “Create Peering Connection.”
  • Once created, select the peering connection and click on “Actions” then “Accept Request” to activate the connection.

3. Update Route Tables

After establishing the peering connection, you need to update the route tables of both VPCs to allow traffic to flow between them:

  • In the VPC Dashboard, click on “Route Tables” in the left navigation pane.
  • First, select the route table associated with your Cloud9 environment’s VPC.
  • Click on the “Routes” tab and then “Edit routes.”
  • Add a new route where the destination is the CIDR block of the EC2 instance’s VPC, and the target is the peering connection.
  • Save the changes.
  • Repeat the above steps for the route table associated with the EC2 instance’s VPC, but this time, the destination will be the CIDR block of the Cloud9 environment’s VPC.

4. Security Groups and Network ACLs

Even with VPC peering in place, security groups and network ACLs will still enforce their rules. Ensure that both VPCs allow the necessary traffic between them. For more common queries related to Cloud9, you might find answers in our Common Cloud9 Questions article.

5. DNS Resolution Across Peering

For DNS resolution to work across peered VPCs:

  • In the VPC Dashboard, click on “Your VPCs.”
  • Select one VPC at a time, click on “Actions,” and ensure that both “Edit DNS resolution” and “Edit DNS hostnames” are set to “yes.”


By following this guide, you can seamlessly connect your AWS Cloud9 environment and EC2 instance, even if they are in separate VPCs. This ensures smooth development and testing processes, eliminating potential network barriers. If you’re also looking to set up Java in your Cloud9 environment, our Setting up Cloud9 for Java and Spring Boot development guide can be a valuable resource. If you need to access your EC2 instance independently over SSH, read our guide on securely connecting to AWS EC2 Instance over SSH.


Do I need VPC peering for Cloud9 and EC2?

If your Cloud9 environment and your EC2 instance are in different VPCs, they won’t be able to communicate directly by default. VPC peering ensures seamless connectivity between them, which is crucial for development and testing processes.

Are there any costs associated with VPC peering?

While creating a VPC peering connection itself is free, data transfer charges apply for the traffic that flows across the connection. It’s always a good idea to check the latest AWS pricing documentation for any updates.

Can I connect my Cloud9 environment to multiple EC2 instances across different VPCs?

Yes, you can set up multiple VPC peering connections for a single VPC. This means your Cloud9 environment can communicate with EC2 instances across different VPCs, provided each pair of VPCs has its own peering connection.

I’ve set up VPC peering between my AWS Cloud9 and EC2 instance, but I still can’t connect. Why?

VPC peering is just one part of the connectivity puzzle. You also need to ensure that security groups, network ACLs, and route tables are correctly configured. For a detailed troubleshooting guide, refer to our article on Resolving Hostname Issues with EC2 Instances in Cloud9.