feat: add support for Terraform modules in tflint (#2297)

* fix: support tflint relative module references

* chore: add test for relative module imports

* chore: add terraform binary

* chore: move tests

* chore: add newlines to tests

* chore: add newlines to tests

* refactor: move terraform get

* refactor: put terraform get back where it was

Co-authored-by: Lukas Gravley <admiralawkbar@github.com>

.automation/test/terraform_tflint/good/terraform_tflint_good_2.tf

@@ -0,0 +1,10 @@
+module "s3_bucket" {
+  source = "terraform-aws-modules/s3-bucket/aws"
+  version = "2.11.1"
+
+  bucket = "test-bucket"
+}
+
+module "good_relative_reference" {
+  source = "../modules/ec2_instance"
+}

.automation/test/terraform_tflint/modules/ec2_instance/main.tf

@@ -0,0 +1,14 @@
+resource "aws_instance" "good" {
+  ami                         = "ami-0ff8a91507f77f867"
+  instance_type               = "t2.small"
+  associate_public_ip_address = false
+
+  vpc_security_group_ids = ["sg-12345678901234567"]
+  metadata_options {
+    http_endpoint = "disabled"
+  }
+
+  ebs_block_device {
+    encrypted = true
+  }
+}

Dockerfile

@@ -14,6 +14,7 @@ FROM yoheimuta/protolint:v0.35.2 as protolint
 FROM golangci/golangci-lint:v1.43.0 as golangci-lint
 FROM koalaman/shellcheck:v0.8.0 as shellcheck
 FROM ghcr.io/terraform-linters/tflint-bundle:v0.34.1.1 as tflint
+FROM hashicorp/terraform:1.1.2 as terraform
 FROM alpine/terragrunt:1.1.2 as terragrunt
 FROM mvdan/shfmt:v3.4.2 as shfmt
 FROM accurics/terrascan:1.13.0 as terrascan
@@ -129,6 +130,11 @@ COPY --from=shellcheck /bin/shellcheck /usr/bin/
 #####################
 COPY --from=golangci-lint /usr/bin/golangci-lint /usr/bin/
 
+#####################
+# Install Terraform #
+#####################
+COPY --from=terraform /bin/terraform /usr/bin/
+
 ##################
 # Install TFLint #
 ##################

lib/functions/worker.sh

@@ -257,6 +257,15 @@ function LintCodebase() {
           cd "${DIR_NAME}" || exit
           ${LINTER_COMMAND} "${FILE_NAME}" 2>&1
         )
+      ############################################################################################
+      # Corner case for TERRAFORM_TFLINT as it cant use the full path and needs to fetch modules #
+      ############################################################################################
+      elif [[ ${FILE_TYPE} == "TERRAFORM_TFLINT" ]]; then
+        LINT_CMD=$(
+          cd "${DIR_NAME}" || exit
+          terraform get 2>&1
+          ${LINTER_COMMAND} "${FILE_NAME}" 2>&1
+        )
       else
         ################################
         # Lint the file with the rules #