resource: use regex replace to match the stack name for cloudformation

Author: dschofie

resource/stack.go

@@ -2,6 +2,7 @@ package resource
 
 import (
 	"fmt"
+	"regexp"
 	"strings"
 	"time"
 
@@ -100,6 +101,9 @@ func (s Stack) CloudformationParametersType() ([]*cloudformation.Parameter, erro
 	return params, nil
 }
 
+// CloudformationStackName returns the corresponding stack name to create in cloudformation.
+//
+// The name needs to match [a-zA-Z][-a-zA-Z0-9]*|arn:[-a-zA-Z0-9:/._+]*
 func (s Stack) CloudformationStackName() *string {
 	// Replace:
 	// - "/" with "-", "/" appears in the path
@@ -112,6 +116,16 @@ func (s Stack) CloudformationStackName() *string {
 		name = name + "-" + s.Region
 	}
 
+	// Stack name needs to start with [a-zA-Z]
+	// Remove leading characters that are not alphabetic
+	firstAlphaRegex := regexp.MustCompile(`^[^a-zA-Z]*`)
+	name = firstAlphaRegex.ReplaceAllString(name, "")
+
+	// Ensure the first character is alphabetic (already guaranteed by the previous step)
+	// Remove or replace all characters that do not match [-a-zA-Z0-9]
+	validCharsRegex := regexp.MustCompile(`[^-a-zA-Z0-9]+`)
+	name = validCharsRegex.ReplaceAllString(name, "-")
+
 	return &name
 }
 

resource/stack_test.go

@@ -41,3 +41,40 @@ func setFields(s *Stack) {
 		}
 	}
 }
+
+func TestCloudformationStackName(t *testing.T) {
+	tests := []struct {
+		input Stack
+
+		want string
+	}{
+		{
+			input: Stack{
+				Name:   "name",
+				Path:   "path",
+				Region: "us-west-2",
+			},
+			want: "name-path-us-west-2",
+		},
+		{
+			input: Stack{
+				Path:   "./path",
+				Region: "us-west-2",
+			},
+			want: "path-us-west-2",
+		},
+		{
+			input: Stack{
+				Name:   "@danny",
+				Path:   "./path",
+				Region: "us-west-2",
+			},
+			want: "danny---path-us-west-2",
+		},
+	}
+
+	for _, tc := range tests {
+		assert.Equal(t, tc.want, *tc.input.CloudformationStackName())
+	}
+
+}