Getting old ouput from Terraform@1.3.7 apply command after changing structure of Terraform-CodePudding

I had old Terraform configuration, worked perfect. In short, I had static website application I needed to deploy using Cloudfront & S3. Then, I need another application to deploy in the same way, but in other sub-domain.

For ease of helping, you can check the full source code here:

Old Terraform configuration: https://github.com/tal-rofe/tf-old

New Terraform configuration: https://github.com/tal-rofe/tf-new

So, my domain is example.io, and in the old configuration I had only static application deployed on app.example.com. But, as I need an another application, it's going to be deployed on docs.example.com. To avoid a lot of code duplication, I decided on creating a local module for deploying a generic application onto Cloudfront & S3. After doing so, seems like terraform apply and terraform plan succeeds (not really, as no resources were changed at all!): Apply complete! Resources: 0 added, 0 changed, 0 destroyed.

Not only no changes, but I get an old output:

cloudfront_distribution_id = "blabla"
eks_kubeconfig = <sensitive>

This cloudfront_distribution_id output, was the correct output using the old configuration. I expect to get these new outputs, as configured:

output "frontend_cloudfront_distribution_id" {
  description = "The distribution ID of deployed Cloudfront frontend"
  value       = module.frontend-static.cloudfront_distribution_id
}

output "docs_cloudfront_distribution_id" {
  description = "The distribution ID of deployed Cloudfront docs"
  value       = module.docs-static.cloudfront_distribution_id
}

output "eks_kubeconfig" {
  description = "EKS Kubeconfig content"
  value       = module.eks-kubeconfig.kubeconfig
  sensitive   = true
}

I'm using GitHub actions to apply my Terraform configuration with these steps:

            - name: Terraform setup
              uses: hashicorp/setup-terraform@v2
              with:
                terraform_wrapper: false

            - name: Terraform core init
              env:
                  TERRAFORM_BACKEND_S3_BUCKET: ${{ secrets.TERRAFORM_BACKEND_S3_BUCKET }}
                  TERRAFORM_BACKEND_DYNAMODB_TABLE: ${{ secrets.TERRAFORM_BACKEND_DYNAMODB_TABLE }}
              run: |
                terraform -chdir="./terraform/core" init \
                -backend-config="bucket=$TERRAFORM_BACKEND_S3_BUCKET" \
                -backend-config="dynamodb_table=$TERRAFORM_BACKEND_DYNAMODB_TABLE" \
                -backend-config="region=$AWS_REGION"
                
            - name: Terraform core plan
              run: terraform -chdir="./terraform/core" plan -no-color -out state.tfplan

            - name: Terraform core apply
              run: terraform -chdir="./terraform/core" apply state.tfplan

I used the same steps in my old & new Terraform configurations. I want to re-use the logic written in my static-app module twice. So basically I want to be able to create static application just by using the module I've configured.

CodePudding user response：

You cannot define the outputs in the root module and expect it to work because you are already using a different module in your static-app module (i.e., you are nesting modules). Since you are using the terraform module there (denoted with source = "terraform-aws-modules/cloudfront/aws") you are limited to what that module provides as outputs and hence can only define those outputs on the module level, not root level. I see you are referencing the EKS output works, but the difference here is that that particular module is not nested and is called directly (from your repo):

module "eks" {
  source  = "terraform-aws-modules/eks/aws"
  version = "19.5.1"
  .
  .
  .
}

The way I would suggest fixing this is to call the Cloudfront module from the root module (i.e., core in your example):

module "frontend-static" {
  source  = "terraform-aws-modules/cloudfront/aws"
  version = "3.1.0"

 ... rest of the configuration ...

}

module "docs-static" {
  source  = "terraform-aws-modules/cloudfront/aws"
  version = "3.1.0"

 ... rest of the configuration ...

}

The outputs you currently have defined in your repo with new configuration (tf-new) should work out-of-the-box with this change. Alternatively, you could write your own module and then you can control which outputs you will have.