fix: add validation for protocol field on service-defaults config entry

agent/structs/config_entry.go

@@ -12,12 +12,11 @@ import (
 	"time"
 
 	"github.com/miekg/dns"
-
-	"github.com/hashicorp/go-multierror"
 	"github.com/mitchellh/hashstructure"
 	"github.com/mitchellh/mapstructure"
 
 	"github.com/hashicorp/consul-net-rpc/go-msgpack/codec"
+	"github.com/hashicorp/go-multierror"
 
 	"github.com/hashicorp/consul/acl"
 	"github.com/hashicorp/consul/agent/cache"
@@ -269,6 +268,12 @@ func (e *ServiceConfigEntry) Validate() error {
 		validationErr = multierror.Append(validationErr, fmt.Errorf("invalid value for balance_inbound_connections: %v", e.BalanceInboundConnections))
 	}
 
+	switch e.Protocol {
+	case "", "http", "http2", "grpc", "tcp":
+	default:
+		validationErr = multierror.Append(validationErr, fmt.Errorf("invalid value for protocol: %v", e.Protocol))
+	}
+
 	// External endpoints are invalid with an existing service's upstream configuration
 	if e.UpstreamConfig != nil && e.Destination != nil {
 		validationErr = multierror.Append(validationErr, errors.New("UpstreamConfig and Destination are mutually exclusive for service defaults"))

agent/structs/config_entry_test.go

@@ -10,12 +10,12 @@ import (
 	"time"
 
 	"github.com/google/go-cmp/cmp"
-	"github.com/hashicorp/hcl"
 	"github.com/mitchellh/copystructure"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
 	"github.com/hashicorp/consul-net-rpc/go-msgpack/codec"
+	"github.com/hashicorp/hcl"
 
 	"github.com/hashicorp/consul/acl"
 	"github.com/hashicorp/consul/agent/cache"
@@ -3225,6 +3225,14 @@ func TestServiceConfigEntry(t *testing.T) {
 			},
 			validateErr: `Invalid MutualTLSMode "invalid-mtls-mode". Must be one of "", "strict", or "permissive".`,
 		},
+		"validate: invalid Protocol in service-defaults": {
+			entry: &ServiceConfigEntry{
+				Kind:     ServiceDefaults,
+				Name:     "web",
+				Protocol: "blah",
+			},
+			validateErr: `invalid value for protocol: blah`,
+		},
 	}
 	testConfigEntryNormalizeAndValidate(t, cases)
 }