ADD RULE aws_s3_bucket_name_length

docs/rules/aws_s3_bucket_name_length.md

@@ -0,0 +1,31 @@
+# aws_s3_bucket_name_length
+
+Ensures all S3 bucket names contains a valid number of characters.
+
+## Example
+
+```hcl
+resource "aws_s3_bucket" "too_long" {
+  bucket = "a-really-ultra-hiper-super-long-foo-bar-baz-bucket-name.domain.test"
+}
+```
+
+```sh
+$ tflint
+1 issue(s) found:
+
+Error: Bucket name "a-really-ultra-hiper-super-long-foo-bar-baz-bucket-name.domain.test" length must be within 3 - 63 character range (aws_s3_bucket_name_length)
+
+  on main.tf line 2:
+  2:   bucket = "a-really-ultra-hiper-super-long-foo-bar-baz-bucket-name.domain.test"
+```
+
+## Why
+
+Amazon S3 bucket names have [restrictive naming rules](https://docs.aws.amazon.com/AmazonS3/latest/userguide/bucketnamingrules.html).
+
+* This rule is specifically for how many characters long a bucket name must have.
+
+## How To Fix
+
+Ensure the bucket name matches the minimum and maximum characters length count.

rules/aws_s3_bucket_name_length.go

@@ -0,0 +1,84 @@
+package rules
+
+import (
+	"fmt"
+
+	"github.com/terraform-linters/tflint-plugin-sdk/hclext"
+	"github.com/terraform-linters/tflint-plugin-sdk/tflint"
+	"github.com/terraform-linters/tflint-ruleset-aws/project"
+)
+
+// AwsS3BucketNameLengthRule checks that an S3 bucket name contains a valid number of characteres
+type AwsS3BucketNameLengthRule struct {
+	tflint.DefaultRule
+
+	resourceType  string
+	attributeName string
+}
+
+// NewAwsS3BucketNameLengthRule returns new rule with default attributes
+func NewAwsS3BucketNameLengthRule() *AwsS3BucketNameLengthRule {
+	return &AwsS3BucketNameLengthRule{
+		resourceType:  "aws_s3_bucket",
+		attributeName: "bucket",
+	}
+}
+
+// Name returns the rule name
+func (r *AwsS3BucketNameLengthRule) Name() string {
+	return "aws_s3_bucket_name_length"
+}
+
+// Enabled returns whether the rule is enabled by default
+func (r *AwsS3BucketNameLengthRule) Enabled() bool {
+	return true
+}
+
+// Severity returns the rule severity
+func (r *AwsS3BucketNameLengthRule) Severity() tflint.Severity {
+	return tflint.ERROR
+}
+
+// Link returns the rule reference link
+func (r *AwsS3BucketNameLengthRule) Link() string {
+	return project.ReferenceLink(r.Name())
+}
+
+// Check if s3 bucket name is within the characteres length accepted range
+func (r *AwsS3BucketNameLengthRule) Check(runner tflint.Runner) error {
+
+	resources, err := runner.GetResourceContent(r.resourceType, &hclext.BodySchema{
+		Attributes: []hclext.AttributeSchema{
+			{Name: r.attributeName},
+		},
+	}, nil)
+	if err != nil {
+		return err
+	}
+
+  bucketNameMinLength := 3
+  bucketNameMaxLength := 63
+
+	for _, resource := range resources.Blocks {
+		attribute, exists := resource.Body.Attributes[r.attributeName]
+		if !exists {
+			continue
+		}
+
+		err := runner.EvaluateExpr(attribute.Expr, func (name string) error {
+      if len(name) < bucketNameMinLength || len(name) > bucketNameMaxLength {
+				runner.EmitIssue(
+					r,
+          fmt.Sprintf("Bucket name %q must be between %d and %d characters", name, bucketNameMinLength, bucketNameMaxLength),
+					attribute.Expr.Range(),
+				)
+			}
+			return nil
+		}, nil)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}

rules/aws_s3_bucket_name_length_test.go

@@ -0,0 +1,48 @@
+package rules
+
+import (
+	"testing"
+
+	hcl "github.com/hashicorp/hcl/v2"
+	"github.com/terraform-linters/tflint-plugin-sdk/helper"
+)
+
+func Test_AwsS3BucketNameLength(t *testing.T) {
+	cases := []struct {
+		Name     string
+		Content  string
+		Expected helper.Issues
+	}{
+		{
+			Name: "basic",
+			Content: `
+resource "aws_s3_bucket" "too_long" {
+  bucket = "a-really-ultra-hiper-super-long-foo-bar-baz-bucket-name.domain.test"
+}
+`,
+			Expected: helper.Issues{
+				{
+					Rule:    NewAwsS3BucketNameLengthRule(),
+					Message: `Bucket name "a-really-ultra-hiper-super-long-foo-bar-baz-bucket-name.domain.test" must be between 3 and 63 characters`,
+					Range: hcl.Range{
+						Filename: "resource.tf",
+						Start:    hcl.Pos{Line: 3, Column: 12},
+						End:      hcl.Pos{Line: 3, Column: 81},
+					},
+				},
+			},
+		},
+	}
+
+	rule := NewAwsS3BucketNameLengthRule()
+
+	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

@@ -39,6 +39,7 @@ var manualRules = []tflint.Rule{
 	NewAwsElasticBeanstalkEnvironmentInvalidNameFormatRule(),
 	NewAwsSecurityGroupInvalidProtocolRule(),
 	NewAwsSecurityGroupRuleInvalidProtocolRule(),
+	NewAwsS3BucketNameLengthRule(),
 }
 
 // Rules is a list of all rules