feat: add aws_security_group_rule_deprecated rule (#790)

* generate rule

* finish coding

* finish docs

* amend docs

* add rule name to output

* Update docs/rules/aws_security_group_rule_deprecated.md

Co-authored-by: Ben Drucker <bvdrucker@gmail.com>

* fix review issues

* get the resource only

* Update README.md

* Update README.md

* Update README.md.tmpl

* Update README.md

---------

Co-authored-by: Ben Drucker <bvdrucker@gmail.com>

docs/rules/README.md

@@ -75,6 +75,7 @@ These rules enforce best practices and naming conventions:
 |[aws_lambda_function_deprecated_runtime](aws_lambda_function_deprecated_runtime.md)|Disallow deprecated runtimes for Lambda Function|✔|
 |[aws_resource_missing_tags](aws_resource_missing_tags.md)|Require specific tags for all AWS resource types that support them||
 |[aws_s3_bucket_name](aws_s3_bucket_name.md)|Ensures all S3 bucket names match the naming rules|✔|
+|[aws_security_group_rule_deprecated](aws_security_group_rule_deprecated.md)|Disallow using `aws_security_group_rule` resource||
 |[aws_provider_missing_default_tags](aws_provider_missing_default_tags.md)|Require specific tags for all AWS providers default tags||
 
 ### SDK-based Validations

docs/rules/README.md.tmpl

@@ -75,6 +75,7 @@ These rules enforce best practices and naming conventions:
 |[aws_lambda_function_deprecated_runtime](aws_lambda_function_deprecated_runtime.md)|Disallow deprecated runtimes for Lambda Function|✔|
 |[aws_resource_missing_tags](aws_resource_missing_tags.md)|Require specific tags for all AWS resource types that support them||
 |[aws_s3_bucket_name](aws_s3_bucket_name.md)|Ensures all S3 bucket names match the naming rules|✔|
+|[aws_security_group_rule_deprecated](aws_security_group_rule_deprecated.md)|Disallow using `aws_security_group_rule` resource||
 |[aws_provider_missing_default_tags](aws_provider_missing_default_tags.md)|Require specific tags for all AWS providers default tags||
 
 ### SDK-based Validations

docs/rules/aws_security_group_rule_deprecated.md

@@ -0,0 +1,30 @@
+# aws_security_group_rule_deprecated
+
+The `aws_security_group_rule` resource should be replaced with `aws_vpc_security_group_egress_rule` or `aws_vpc_security_group_ingress_rule`. It lacks support of unique IDs, tags, and descriptions, and has difficulties managing multiple CIDR blocks.
+
+## Example
+
+```hcl
+resource "aws_security_group_rule" "foo" {
+  security_group_id = "sg-12345678"
+  type              = "ingress"
+}
+```
+
+```sh
+❯ tflint
+1 issue(s) found:
+
+Warning: Consider using aws_vpc_security_group_egress_rule or aws_vpc_security_group_ingress_rule instead. (aws_security_group_rule_deprecated)
+
+  on bastion.tf line 4:
+   4:   resource "aws_security_group_rule" "foo" {
+```
+
+## Why
+
+Avoid using the [`aws_security_group_rule`](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/security_group_rule) resource because it has difficulties managing multiple CIDR blocks and historically lacks unique IDs, tags, and descriptions. To prevent these issues, follow the current best practice of using the `aws_vpc_security_group_egress_rule` and `aws_vpc_security_group_ingress_rule` resources.
+
+## How To Fix
+
+Depending on `type`, you can fix the issue by using either `aws_vpc_security_group_egress_rule` or `aws_vpc_security_group_ingress_rule`.

rules/aws_security_group_rule_deprecated.go

@@ -0,0 +1,61 @@
+package rules
+
+import (
+	"github.com/terraform-linters/tflint-plugin-sdk/hclext"
+	"github.com/terraform-linters/tflint-plugin-sdk/tflint"
+	"github.com/terraform-linters/tflint-ruleset-aws/project"
+)
+
+// AwsSecurityGroupRuleDeprecatedRule checks that aws_security_group_rule is not used
+type AwsSecurityGroupRuleDeprecatedRule struct {
+	tflint.DefaultRule
+
+	resourceType  string
+	attributeName string
+}
+
+// NewAwsSecurityGroupRuleDeprecatedRule returns new rule with default attributes
+func NewAwsSecurityGroupRuleDeprecatedRule() *AwsSecurityGroupRuleDeprecatedRule {
+	return &AwsSecurityGroupRuleDeprecatedRule{
+		resourceType:  "aws_security_group_rule",
+		attributeName: "security_group_id",
+	}
+}
+
+// Name returns the rule name
+func (r *AwsSecurityGroupRuleDeprecatedRule) Name() string {
+	return "aws_security_group_rule_deprecated"
+}
+
+// Enabled returns whether the rule is enabled by default
+func (r *AwsSecurityGroupRuleDeprecatedRule) Enabled() bool {
+	return false
+}
+
+// Severity returns the rule severity
+func (r *AwsSecurityGroupRuleDeprecatedRule) Severity() tflint.Severity {
+	return tflint.WARNING
+}
+
+// Link returns the rule reference link
+func (r *AwsSecurityGroupRuleDeprecatedRule) Link() string {
+	return project.ReferenceLink(r.Name())
+}
+
+// Check that aws_security_group_rule resource is not used
+func (r *AwsSecurityGroupRuleDeprecatedRule) Check(runner tflint.Runner) error {
+	resources, err := runner.GetResourceContent(r.resourceType, &hclext.BodySchema{}, nil)
+	if err != nil {
+		return err
+	}
+
+	for _, resource := range resources.Blocks {
+		runner.EmitIssue(
+			r,
+			"Consider using aws_vpc_security_group_egress_rule or aws_vpc_security_group_ingress_rule instead.",
+			resource.DefRange,
+		)
+	}
+
+	return nil
+}

rules/aws_security_group_rule_deprecated_test.go

@@ -0,0 +1,57 @@
+package rules
+
+import (
+	"testing"
+
+	hcl "github.com/hashicorp/hcl/v2"
+	"github.com/terraform-linters/tflint-plugin-sdk/helper"
+)
+
+func Test_AwsSecurityGroupRuleDeprecated(t *testing.T) {
+	cases := []struct {
+		Name     string
+		Content  string
+		Expected helper.Issues
+	}{
+		{
+			Name: "resource is used",
+			Content: `
+resource "aws_security_group_rule" "test" {
+	security_group_id = "sg-12345678"
+}
+`,
+			Expected: helper.Issues{
+				{
+					Rule:    NewAwsSecurityGroupRuleDeprecatedRule(),
+					Message: "Consider using aws_vpc_security_group_egress_rule or aws_vpc_security_group_ingress_rule instead.",
+					Range: hcl.Range{
+						Filename: "resource.tf",
+						Start:    hcl.Pos{Line: 2, Column: 1},
+						End:      hcl.Pos{Line: 2, Column: 42},
+					},
+				},
+			},
+		},
+		{
+			Name: "everything is fine",
+			Content: `
+resource "aws_security_group" "test" {
+	name = "test"
+}
+`,
+			Expected: helper.Issues{},
+		},
+	}
+
+	rule := NewAwsSecurityGroupRuleDeprecatedRule()
+
+	for _, tc := range cases {
+		runner := helper.TestRunner(t, map[string]string{"resource.tf": tc.Content})
+
+		if err := rule.Check(runner); err != nil {
+			t.Fatalf("Unexpected error occurred: %s", err)
+		}
+
+		helper.AssertIssues(t, tc.Expected, runner.Issues)
+	}
+}

rules/provider.go

@@ -41,6 +41,7 @@ var manualRules = []tflint.Rule{
 	NewAwsSecurityGroupInvalidProtocolRule(),
 	NewAwsSecurityGroupRuleInvalidProtocolRule(),
 	NewAwsProviderMissingDefaultTagsRule(),
+	NewAwsSecurityGroupRuleDeprecatedRule(),
 }
 
 // Rules is a list of all rules