Allow underscore in database_name [redshift] (#10019)

* allow underscore in database_name [redshift]

Fixes #10009

* Added Test Cases To Validate Redshift DBName

* Remove Old Test Cases Regarding Redshift DBName Validation

* Added More Test Cases For Redshift DBName

builtin/providers/aws/resource_aws_redshift_cluster.go

@@ -844,9 +844,13 @@ func validateRedshiftClusterIdentifier(v interface{}, k string) (ws []string, er
 
 func validateRedshiftClusterDbName(v interface{}, k string) (ws []string, errors []error) {
 	value := v.(string)
-	if !regexp.MustCompile(`^[0-9a-z]+$`).MatchString(value) {
+	if !regexp.MustCompile(`^[0-9A-Za-z_$]+$`).MatchString(value) {
 		errors = append(errors, fmt.Errorf(
-			"only lowercase letters and numeric characters allowed in %q", k))
+			"only alphanumeric characters, underscores, and dollar signs are allowed in %q", k))
+	}
+	if !regexp.MustCompile(`^[a-zA-Z_]`).MatchString(value) {
+		errors = append(errors, fmt.Errorf(
+			"first character of %q must be a letter or underscore", k))
 	}
 	if len(value) > 64 {
 		errors = append(errors, fmt.Errorf(

builtin/providers/aws/resource_aws_redshift_cluster_test.go

@@ -13,6 +13,42 @@ import (
 	"github.com/hashicorp/terraform/terraform"
 )
 
+func TestValidateRedshiftClusterDbName(t *testing.T) {
+	validNames := []string{
+		"testdbname",
+		"test_dbname",
+		"testdbname123",
+		"TestDBname",
+		"testdbname$hashicorp",
+		"_dbname",
+	}
+	for _, v := range validNames {
+		_, errors := validateRedshiftClusterDbName(v, "name")
+		if len(errors) != 0 {
+			t.Fatalf("%q should be a valid Redshift DBName: %q", v, errors)
+		}
+	}
+
+	invalidNames := []string{
+		"!",
+		"/",
+		" ",
+		":",
+		";",
+		"test name",
+		"/slash-at-the-beginning",
+		"slash-at-the-end/",
+		"",
+		randomString(100),
+	}
+	for _, v := range invalidNames {
+		_, errors := validateRedshiftClusterDbName(v, "name")
+		if len(errors) == 0 {
+			t.Fatalf("%q should be an invalid Redshift DBName", v)
+		}
+	}
+}
+
 func TestAccAWSRedshiftCluster_basic(t *testing.T) {
 	var v redshift.Cluster
 
@@ -340,42 +376,6 @@ func TestResourceAWSRedshiftClusterIdentifierValidation(t *testing.T) {
 	}
 }
 
-func TestResourceAWSRedshiftClusterDbNameValidation(t *testing.T) {
-	cases := []struct {
-		Value    string
-		ErrCount int
-	}{
-		{
-			Value:    "tEsting",
-			ErrCount: 1,
-		},
-		{
-			Value:    "testing1",
-			ErrCount: 0,
-		},
-		{
-			Value:    "testing-",
-			ErrCount: 1,
-		},
-		{
-			Value:    "",
-			ErrCount: 2,
-		},
-		{
-			Value:    randomString(65),
-			ErrCount: 1,
-		},
-	}
-
-	for _, tc := range cases {
-		_, errors := validateRedshiftClusterDbName(tc.Value, "aws_redshift_cluster_database_name")
-
-		if len(errors) != tc.ErrCount {
-			t.Fatalf("Expected the Redshift Cluster database_name to trigger a validation error")
-		}
-	}
-}
-
 func TestResourceAWSRedshiftClusterFinalSnapshotIdentifierValidation(t *testing.T) {
 	cases := []struct {
 		Value    string