How to Create an aws_instance with an Existing VPC Using Terraform

Learn how to launch an EC2 instance within an existing VPC using Terraform, addressing common issues and the proper configuration needed. --- This video is based on the question https://stackoverflow.com/q/65860901/ asked by the user 'Tar' ( https://stackoverflow.com/u/587467/ ) and on the answer https://stackoverflow.com/a/65871084/ provided by the user 'Benoit74B' ( https://stackoverflow.com/u/3852126/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions. Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: How to create aws_instance with existing VPC? Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l... The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license. If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com. --- How to Create an aws_instance with an Existing VPC Using Terraform Creating an EC2 instance in a specific Virtual Private Cloud (VPC) setup can be tricky, especially for those who are new to Amazon Web Services (AWS) and Terraform. One common challenge developers face is how to correctly configure an aws_instance resource while reusing an existing VPC without running into errors. In this guide, we will break down the solution step-by-step so you can easily deploy your instance without unnecessary hassles. Understanding the Problem When attempting to create an EC2 instance using Terraform with an existing VPC, you might encounter an error like this: [[See Video to Reveal this Text or Code Snippet]] This typically means that the aws_instance resource you are trying to create is not properly associated with the desired VPC, which is essential for successful deployment. Simplifying the Solution Essential Parameters To create an aws_instance within a specified VPC, you need to ensure that two vital parameters are set within your Terraform code: VPC Security Group ID: This ensures that your instance is protected by security group rules. Subnet ID: This tells Terraform to place your instance in the correct subnet within the VPC. Step-by-Step Configuration Let’s go through the necessary Terraform configuration to successfully create your instance. Step 1: Define Security Group Data Block First, set up your security group. This part of the code retrieves an existing security group by its name. [[See Video to Reveal this Text or Code Snippet]] Step 2: Define Subnet Data Block Next, define the subnet where your instance will reside. Again, we will retrieve this using its tags. [[See Video to Reveal this Text or Code Snippet]] Step 3: Create the EC2 Instance Now, we will incorporate the data from the previous two blocks into our aws_instance resource definition. [[See Video to Reveal this Text or Code Snippet]] Key Points to Remember Subnets and VPCs: Make sure that both the security group and the subnet belong to the same VPC. Single Security Group: In your aws_instance block, ensure you are referencing a single security group's ID correctly to avoid conflicts. Troubleshooting Errors If you encounter conflicts such as "network_interface": conflicts with vpc_security_group_ids, it may be due to settings in your instance that try to create both a network interface and specify vpc_security_group_ids. To resolve this, ensure that your aws_instance resource is appropriately configured. Removing the conflicting parameters usually will solve the issue. Conclusion Deploying an EC2 instance in an existing VPC using Terraform can be a straightforward task if you follow the correct approach and understand the necessary configurations. By defining the security group and subnet properly and ensuring they are associated with the correct VPC, you can set up your infrastructure efficiently. Now, you're ready to launch an aws_instance like a pro! Remember to review your Terraform code for any further optimizations or configurations that might be unique to your project. Happy coding!