Update shard validation

Author: mjudeikis

pkg/admission/shard/admission.go

@@ -65,6 +65,15 @@ func (o *shard) Admit(_ context.Context, a admission.Attributes, _ admission.Obj
 		return fmt.Errorf("failed to convert unstructured to Shard: %w", err)
 	}
 
+	// If you reading this - this is probably not what you looking for.
+	// Defaulting happens in pkg/server/config.go#L561, and these becomes no-op.
+	// The only case where these will be used, if somebody is creating Shard
+	// objects directly or using kcp as a library and skipping defaulting in config.go.
+	// So if you not sure what is happening - its probably better to be explicit and set these flags.
+	// But if you are doing that - you probably know what you are doing :)
+	if wShard.Spec.BaseURL == "" {
+		return fmt.Errorf("spec.baseURL is required")
+	}
 	if wShard.Spec.ExternalURL == "" {
 		wShard.Spec.ExternalURL = wShard.Spec.BaseURL
 	}

pkg/admission/shard/admission_test.go

@@ -128,9 +128,9 @@ func TestAdmit(t *testing.T) {
 		expected *corev1alpha1.Shard
 	}{
 		{
-			name:     "nothing set",
-			shard:    newShard().Shard,
-			expected: newShard().Shard,
+			name:     "only base URL set (default)",
+			shard:    newShard().baseURL("https://test").Shard,
+			expected: newShard().baseURL("https://test").externalURL("https://test").virtualWorkspaceURL("https://test").Shard,
 		},
 		{
 			name:     "all set",

pkg/server/config.go

@@ -562,13 +562,13 @@ func NewConfig(ctx context.Context, opts kcpserveroptions.CompletedOptions) (*Co
 		if opts.Extra.ShardExternalURL != "" {
 			return opts.Extra.ShardExternalURL
 		}
-		return "https://" + c.GenericConfig.ExternalAddress
+		return c.ShardBaseURL()
 	}
 	c.ShardVirtualWorkspaceURL = func() string {
 		if opts.Extra.ShardVirtualWorkspaceURL != "" {
 			return opts.Extra.ShardVirtualWorkspaceURL
 		}
-		return "https://" + c.GenericConfig.ExternalAddress
+		return c.ShardBaseURL()
 	}
 
 	serviceResolver := webhook.NewDefaultServiceResolver()