Terragrunt use resources from other enviroment - amazon-web-services

Question

I want to use resources, in this case the output of the vpc module, in another environment.
Goal is to reduce the costs for the customer with resources of stage and dev in the same vpc.
Stage and dev have seperate ecs-cluster, asg, lc, different docker images in ecr etc but should be in the same vpc with the same load balancer and then a host header listener to forward to the specific target group.
Both should use the same database and the same load balancer.
Requirement was to have n Customer each with stage, dev and prod environments.
All Customer folders should contain the three environments.
My folder structure is
├── Terraform
│   ├── Customer1
│   ├── Customer2
│   ├── Customer3
│   ├── Customer4
│   ├── Customer5
│   ├── Global
│   │   ├── iam
│   │   │   └── terragrunt.hcl
│   ├── README.md
│   └── Customer6
│   ├── non-prod
│   │   ├── eu-central-1
│   │   │   ├── dev
│   │   │   │   ├── cloudwatch
│   │   │   │   │   └── terragrunt.hcl
│   │   │   │   ├── ec2
│   │   │   │   │   └── terragrunt.hcl
│   │   │   │   ├── ecs
│   │   │   │   │   └── terragrunt.hcl
│   │   │   │   ├── lambda
│   │   │   │   │   └── terragrunt.hcl
│   │   │   │   ├── rds
│   │   │   │   │   └── terragrunt.hcl
│   │   │   │   ├── terragrunt.hcl
│   │   │   │   ├── vars.hcl
│   │   │   │   └── vpc
│   │   │   │   └── terragrunt.hcl
│   │   │   ├── region.hcl
│   │   │   └── stage
│   │   │   ├── cloudwatch
│   │   │   │   └── terragrunt.hcl
│   │   │   ├── ec2
│   │   │   │   └── terragrunt.hcl
│   │   │   ├── ecs
│   │   │   │   └── terragrunt.hcl
│   │   │   ├── lambda
│   │   │   │   └── terragrunt.hcl
│   │   │   ├── rds
│   │   │   │   └── terragrunt.hcl
│   │   │   ├── terragrunt.hcl
│   │   │   ├── vars.hcl
│   │   │   └── vpc
│   │   │   └── terragrunt.hcl
│   │   └── terragrunt.hcl
│   └── prod
│   └── eu-central-1
│   ├── prod
│   │   ├── cloudwatch
│   │   │   └── terragrunt.hcl
│   │   ├── ec2
│   │   │   └── terragrunt.hcl
│   │   ├── ecs
│   │   │   └── terragrunt.hcl
│   │   ├── lambda
│   │   │   └── terragrunt.hcl
│   │   ├── rds
│   │   │   └── terragrunt.hcl
│   │   ├── terragrunt.hcl
│   │   ├── vars.hcl
│   │   └── vpc
│   │   └── terragrunt.hcl
│   └── region.hcl
└── Modules
├── cloudwatch
│   ├── Main.tf
│   ├── Outputs.tf
│   └── Variables.tf
├── ec2
│   ├── Main.tf
│   ├── Outputs.tf
│   └── Variables.tf
├── ecs
│   ├── Main.tf
│   ├── Outputs.tf
│   └── Variables.tf
├── iam
│   ├── Main.tf
│   ├── Outputs.tf
│   └── Variables.tf
├── lambda
│   ├── Main.tf
│   ├── Outputs.tf
│   └── Variables.tf
├── rds
│   ├── Main.tf
│   ├── Outputs.tf
│   └── Variables.tf
├── vpc
│   ├── Main.tf
│   ├── Outputs.tf
│   ├── Variables.tf
└── vpc-stage
├── Main.tf
├── Outputs.tf
└── Variables.tf
I've read about data terraform_remote_state but that's on module layer.
For me it's not a good approach to do this in the module layer cause it's
only for the stage enviroment.
Is there a way to get the output from the remote state in the terragrunt.hcl in the stage folder from the dev environment to use this as input for the ec2 module?
I've used
dependency "vpc" {
config_path = "../vpc"
}
and then
vpc_id = dependency.vpc.outputs.vpc_id
for the input of ec2 module but that's only if it's in the same enviroment.
Best regards.

Answer 1

In the directory structure you've show above, you have a VPC in both the dev and stage environments. It sounds like you want dev and stage to share a VPC, so the first thing to do is move that VPC directory outside of dev and stage. Put the vpc under eu-west-1, then you can use it as a dependency within both dev and stage as you desire.
Customer6
│ ├── non-prod
└── eu-central-1
├── dev
│ └── ecs
├── stage
│ └── ecs
└── vpc
dependency "vpc" {
config_path = "../../vpc"
}
Refer to the Terragrunt docs on Passing outputs between modules.