Add support for multiple alias and remove duplication of SSL certificates (#4472)

internal/ingress/annotations/alias/main.go

@@ -17,7 +17,11 @@ limitations under the License.
 package alias
 
 import (
+	"sort"
+	"strings"
+
 	networking "k8s.io/api/networking/v1beta1"
+	"k8s.io/apimachinery/pkg/util/sets"
 
 	"k8s.io/ingress-nginx/internal/ingress/annotations/parser"
 	"k8s.io/ingress-nginx/internal/ingress/resolver"
@@ -35,5 +39,25 @@ func NewParser(r resolver.Resolver) parser.IngressAnnotation {
 // Parse parses the annotations contained in the ingress rule
 // used to add an alias to the provided hosts
 func (a alias) Parse(ing *networking.Ingress) (interface{}, error) {
-	return parser.GetStringAnnotation("server-alias", ing)
+	val, err := parser.GetStringAnnotation("server-alias", ing)
+	if err != nil {
+		return []string{}, err
+	}
+
+	aliases := sets.NewString()
+	for _, alias := range strings.Split(val, ",") {
+		alias = strings.TrimSpace(alias)
+		if len(alias) == 0 {
+			continue
+		}
+
+		if !aliases.Has(alias) {
+			aliases.Insert(alias)
+		}
+	}
+
+	l := aliases.List()
+	sort.Strings(l)
+
+	return l, nil
 }

internal/ingress/annotations/alias/main_test.go

@@ -17,6 +17,7 @@ limitations under the License.
 package alias
 
 import (
+	"reflect"
 	"testing"
 
 	api "k8s.io/api/core/v1"
@@ -36,14 +37,15 @@ func TestParse(t *testing.T) {
 
 	testCases := []struct {
 		annotations map[string]string
-		expected    string
+		expected    []string
 	}{
-		{map[string]string{annotation: "www.example.com"}, "www.example.com"},
-		{map[string]string{annotation: "*.example.com www.example.*"}, "*.example.com www.example.*"},
-		{map[string]string{annotation: `~^www\d+\.example\.com$`}, `~^www\d+\.example\.com$`},
-		{map[string]string{annotation: ""}, ""},
-		{map[string]string{}, ""},
-		{nil, ""},
+		{map[string]string{annotation: "a.com, b.com, ,    c.com"}, []string{"a.com", "b.com", "c.com"}},
+		{map[string]string{annotation: "www.example.com"}, []string{"www.example.com"}},
+		{map[string]string{annotation: "*.example.com,www.example.*"}, []string{"*.example.com", "www.example.*"}},
+		{map[string]string{annotation: `~^www\d+\.example\.com$`}, []string{`~^www\d+\.example\.com$`}},
+		{map[string]string{annotation: ""}, []string{}},
+		{map[string]string{}, []string{}},
+		{nil, []string{}},
 	}
 
 	ing := &networking.Ingress{
@@ -57,7 +59,7 @@ func TestParse(t *testing.T) {
 	for _, testCase := range testCases {
 		ing.SetAnnotations(testCase.annotations)
 		result, _ := ap.Parse(ing)
-		if result != testCase.expected {
+		if !reflect.DeepEqual(result, testCase.expected) {
 			t.Errorf("expected %v but returned %v, annotations: %s", testCase.expected, result, testCase.annotations)
 		}
 	}

internal/ingress/annotations/annotations.go

@@ -74,7 +74,7 @@ const DeniedKeyName = "Denied"
 type Ingress struct {
 	metav1.ObjectMeta
 	BackendProtocol      string
-	Alias                string
+	Aliases              []string
 	BasicDigestAuth      auth.Config
 	Canary               canary.Config
 	CertificateAuth      authtls.Config
@@ -124,7 +124,7 @@ type Extractor struct {
 func NewAnnotationExtractor(cfg resolver.Resolver) Extractor {
 	return Extractor{
 		map[string]parser.IngressAnnotation{
-			"Alias":                alias.NewParser(cfg),
+			"Aliases":              alias.NewParser(cfg),
 			"BasicDigestAuth":      auth.NewParser(auth.AuthDirectory, cfg),
 			"Canary":               canary.NewParser(cfg),
 			"CertificateAuth":      authtls.NewParser(cfg),