tflint --recursive --call-module-type=all cannot find nested local modules

[mdowling17]

Summary

When running tflint --recursive --call-module-type=all with a file directory that contains nested local modules (that is local modules that call other remote/local modules), tflint says Error: "module1" module is not found. Did you run "terraform init"? It seems to expect that I go into each of my local modules and run terraform init. That seems totally unnecessary since it should be able to figure things out by looking at my root .terraform/modules folder created by running terraform init in the root.

Command

tflint --recursive --call-module-type=all

Terraform Configuration

$ tree
.
├── README.md
├── backend.tf
├── locals.tf
├── main.tf
├── modules
│   ├── module1
│   │   ├── main.tf
│   │   └── outputs.tf
│   ├── module2
│   │   ├── main.tf
│   │   └── variables.tf
│   ├── module3
│   │   ├── backend.tf
│   │   ├── main.tf
│   │   ├── outputs.tf
│   │   └── variables.tf
│   ├── module4
│   │   ├── main.tf
│   │   └── variables.tf
│   ├── module5
│   │   ├── main.tf
│   │   ├── outputs.tf
│   │   └── variables.tf
│   ├── module6
│   │   ├── main.tf
│   │   └── outputs.tf
│   └── module7
│       ├── main.tf
│       ├── outputs.tf
│       └── variables.tf
├── moved.tf
└── variables.tf

TFLint Configuration

plugin "terraform" {
  enabled = true
  preset  = "recommended"
}

config {
  call_module_type = "all"
}

rule "terraform_required_version" {
  enabled = false
}

rule "terraform_required_providers" {
  enabled = false
}

Output

│ Failed to run in modules/module7; exit status 1

Failed to load configurations; modules/module7/main.tf:23,1-33: "module8" module is not found. Did you run "terraform init"?; :

Error: "module8" module is not found. Did you run "terraform init"?

  on modules/module7/main.tf line 23, in module "module8":
  23: module "module8" {


│ Failed to run in modules/module3; exit status 1

Failed to load configurations; modules/module3/main.tf:14,1-16: "module9" module is not found. Did you run "terraform init"?; , and 1 other diagnostic(s):

Error: "module9" module is not found. Did you run "terraform init"?

  on modules/module3/main.tf line 14, in module "module9":
  14: module "module9" {

Error: "module10" module is not found. Did you run "terraform init"?

  on modules/module3/main.tf line 20, in module "module10":
  20: module "module10" {

TFLint Version

0.51.2

Terraform Version

1.5.7

Operating System

• Linux
• macOS
• Windows

[bendrucker]

If you recurse, those modules that you recurse into need to be properly initialized. Recursing and child module calls are entirely different things. Child modules have a formal tree relationship. Recursion assumes a tree structure of directories, but makes no logical assumptions about the relationships of those directories. Every recursed directory is an independent entity. When you've recursed into your child directories, there is no relationship that TFLint sees between your repository root and the module directory at that point.

[mdowling17]

But if I set it to tflint --recursive --call-module-type=local it works as expected without having to initialize each local module. The limitation with that approach, I presume, is that now it won't inspect remote modules. In my regular terraform workflow I would never run terraform init in each local module, rather I'd just run it in the root and it will generate all the submodules relative to the root and terraform plan works just fine. It'd be nice if tflint could do the same and simply refer to the root .terraform/modules folder to understand the tree structure.

[wata727]

For local modules there is a special optimization that allows child modules to be loaded without .terraform/modules. This is why --call-module-type=local works without terraform init.

Initially, I was planning on providing a solution to --recursive + --call-module-type=all issue, which would be to provide a terraform init hook that would be run in each subdirectory #1930, but it seems interesting that maybe terraform init at the root module would be able to load the remote modules we need if we could resolve their addresses.

The issue here is that not all subdirectories are referenced from the root module. If the module7 is not referenced from the root module, remote modules contained in it may not be included in the root .terraform/modules. In this case, the difficult part seems to be how to resolve the child modules when inspecting the module7 by --recursive.