Update all versions of the same private module in single terraform file

terraform/lib/dependabot/terraform/file_updater.rb

@@ -48,6 +48,30 @@ def updated_dependency_files
 
       private
 
+      # Terraform allows to use a module from the same source multiple times
+      # To detect any changes in dependencies we need to overwrite an implementation from the base class
+      #
+      # Example (for simplicity other parameters are skipped):
+      # previous_requirements = [{requirement: "0.9.1"}, {requirement: "0.11.0"}]
+      # requirements = [{requirement: "0.11.0"}, {requirement: "0.11.0"}]
+      #
+      # Simple difference between arrays gives:
+      # requirements - previous_requirements
+      #  => []
+      # which loses an information that one of our requirements has changed.
+      #
+      # By using symmetric difference:
+      # (requirements - previous_requirements) | (previous_requirements - requirements)
+      #  => [{requirement: "0.9.1"}]
+      # we can detect that change.
+      def requirement_changed?(file, dependency)
+        changed_requirements =
+          (dependency.requirements - dependency.previous_requirements) |
+          (dependency.previous_requirements - dependency.requirements)
+
+        changed_requirements.any? { |f| f[:file] == file.name }
+      end
+
       def updated_terraform_file_content(file)
         content = file.content.dup
 
@@ -89,7 +113,7 @@ def update_git_declaration(new_req, old_req, updated_content, filename)
 
       def update_registry_declaration(new_req, old_req, updated_content)
         regex = new_req[:source][:type] == "provider" ? provider_declaration_regex : registry_declaration_regex
-        updated_content.sub!(regex) do |regex_match|
+        updated_content.gsub!(regex) do |regex_match|
           regex_match.sub(/^\s*version\s*=.*/) do |req_line_match|
             req_line_match.sub(old_req[:requirement], new_req[:requirement])
           end

terraform/spec/dependabot/terraform/file_updater_spec.rb

@@ -122,6 +122,75 @@ module "s3-webapp" {
       end
     end
 
+    context "with private modules with different versions" do
+      let(:project_name) { "private_modules_with_different_versions" }
+
+      let(:dependencies) do
+        [
+          Dependabot::Dependency.new(
+            name: "example-org-5d3190/s3-webapp/aws",
+            version: "0.11.0",
+            previous_version: "0.9.1",
+            requirements: [{
+              requirement: "0.11.0",
+              groups: [],
+              file: "main.tf",
+              source: {
+                type: "registry",
+                registry_hostname: "app.terraform.io",
+                module_identifier: "example-org-5d3190/s3-webapp/aws"
+              }
+            }, {
+              requirement: "0.11.0",
+              groups: [],
+              file: "main.tf",
+              source: {
+                type: "registry",
+                registry_hostname: "app.terraform.io",
+                module_identifier: "example-org-5d3190/s3-webapp/aws"
+              }
+            }],
+            previous_requirements: [{
+              requirement: "0.9.1",
+              groups: [],
+              file: "main.tf",
+              source: {
+                type: "registry",
+                registry_hostname: "app.terraform.io",
+                module_identifier: "example-org-5d3190/s3-webapp/aws"
+              }
+            }, {
+              requirement: "0.11.0",
+              groups: [],
+              file: "main.tf",
+              source: {
+                type: "registry",
+                registry_hostname: "app.terraform.io",
+                module_identifier: "example-org-5d3190/s3-webapp/aws"
+              }
+            }],
+            package_manager: "terraform"
+          )
+        ]
+      end
+
+      it "updates all private modules versions" do
+        updated_file = subject.find { |file| file.name == "main.tf" }
+
+        expect(updated_file.content).to include(<<~HCL)
+          module "s3-webapp-first" {
+            source  = "app.terraform.io/example-org-5d3190/s3-webapp/aws"
+            version = "0.11.0"
+          }
+
+          module "s3-webapp-second" {
+            source  = "app.terraform.io/example-org-5d3190/s3-webapp/aws"
+            version = "0.11.0"
+          }
+        HCL
+      end
+    end
+
     context "with a private provider" do
       let(:project_name) { "private_provider" }
 

terraform/spec/fixtures/projects/private_modules_with_different_versions/main.tf

@@ -0,0 +1,9 @@
+module "s3-webapp-first" {
+  source  = "app.terraform.io/example-org-5d3190/s3-webapp/aws"
+  version = "0.11.0"
+}
+
+module "s3-webapp-second" {
+  source  = "app.terraform.io/example-org-5d3190/s3-webapp/aws"
+  version = "0.9.1"
+}