Backend must be defined

Gruntwork Customers
1

I have a terragrunt project setup with a folder structure near identical of https://github.com/gruntwork-io/terragrunt-infrastructure-live-example/blob/master/prod/terraform.tfvars for testing. When I run terragrunt init, I’m getting an error of You must define a backend block (it can be empty!). But the backend is defined in the terraform.tfvars. Do I also need to define it in something like backend.tf?

terragrunt = {
  # Configure Terragrunt to automatically store tfstate files in an S3 bucket
  remote_state {
    backend = "s3"
   ...
2

As the error says, you must have a backend "s3" {} block in your Terraform code—that is, the .tf files. See https://github.com/gruntwork-io/terragrunt#motivation-1.

3

Ah, but if all I’m looking to do is run all modules in a region, I don’t have to run terragrunt init from the root directory, and instead just use terragrunt plan-all

4

The plan-all command will run init automatically in each module. That doesn’t change the fact that in each module you must have an empty backend "s3" {} block defined. Otherwise, Terraform won’t configure a backend at all.

1 Like
5

I’m running into the same issue and could use a pointer. I’m starting off with terragrunt-infrastructure-live-example and added s3 module https://github.com/cloudposse/terraform-aws-s3-bucket. The S3 module doesn’t have a default partial backend which is why i’m seeing the error. What’s the best way to declare it?

6

Create your own module that creates an S3 bucket (possibly using another module under the hood) and has a backend "..." {} block.

7

I would like use existing terraform modules on the community registry, rather then creating my own modules. From what I can see most of the AWS modules doesn’t have a default partial backend block. Jim is there a way i could use terragrunt to keep the backend DRY with community modules?

8

You can generate a backend.tf on the fly with a hook.