address code review

config/constants.go

@@ -40,5 +40,4 @@ var ViperPolicyHooks = viper.DecodeHook(mapstructure.ComposeDecodeHookFunc(
 	decodePPLPolicyHookFunc(),
 	decodeSANMatcherHookFunc(),
 	decodeStringToMapHookFunc(),
-	decodeRuntimeFlagsHookFunc(),
 ))

config/custom.go

@@ -549,46 +549,6 @@ var (
 	ErrRuntimeFlagInvalidMapValue = fmt.Errorf("decoding runtime flags: unknown flag value (expected bool)")
 )
 
-// only for RuntimeFlags decoding
-func decodeRuntimeFlagsHookFunc() mapstructure.DecodeHookFunc {
-	return mapstructure.DecodeHookFuncType(func(from, to reflect.Type, data any) (any, error) {
-		if to != reflect.TypeOf(RuntimeFlags{}) {
-			return data, nil
-		}
-		if from.Kind() != reflect.Map {
-			return nil, fmt.Errorf("%w: got %s", ErrRuntimeFlagsInvalidValue, from.Kind())
-		}
-
-		src, ok := data.(map[string]interface{})
-		if !ok {
-			return nil, fmt.Errorf("decoding runtime flags: expected map[string]interface{}, got %T", from.String())
-		}
-
-		dst := make(RuntimeFlags)
-		// copy default flags first
-		// this is to ensure we don't lose any default flags and only override the ones that are provided
-		for k, v := range defaultRuntimeFlags {
-			dst[k] = v
-		}
-
-		for k, v := range src {
-			key := RuntimeFlag(k)
-			if _, ok := dst[key]; !ok {
-				return nil, fmt.Errorf("%s: %w", k, ErrRuntimeFlagUnknown)
-			}
-
-			b, ok := v.(bool)
-			if !ok {
-				return nil, fmt.Errorf("%w: got %T", ErrRuntimeFlagInvalidMapValue, v)
-			}
-
-			dst[key] = b
-		}
-
-		return dst, nil
-	})
-}
-
 // serializable converts mapstructure nested map into map[string]interface{} that is serializable to JSON
 func serializable(in interface{}) (interface{}, error) {
 	switch typed := in.(type) {

config/custom_test.go

@@ -3,7 +3,6 @@ package config
 import (
 	"encoding/base64"
 	"encoding/json"
-	"strings"
 	"testing"
 
 	"github.com/mitchellh/mapstructure"
@@ -184,102 +183,3 @@ func TestDecodePPLPolicyHookFunc(t *testing.T) {
 		},
 	}, withPolicy.Policy)
 }
-
-func TestDecodeRuntimeFlagsHookFunc(t *testing.T) {
-	t.Parallel()
-
-	t.Run("valid", func(t *testing.T) {
-		t.Parallel()
-
-		defaults := DefaultRuntimeFlags()
-		withMap := struct {
-			SomethingElse map[string]bool `mapstructure:"something_else"`
-			RuntimeFlags  RuntimeFlags    `mapstructure:"runtime_flags"`
-		}{
-			RuntimeFlags: defaults,
-		}
-
-		decoder, err := mapstructure.NewDecoder(&mapstructure.DecoderConfig{
-			DecodeHook: decodeRuntimeFlagsHookFunc(),
-			Result:     &withMap,
-		})
-		require.NoError(t, err)
-
-		expect := DefaultRuntimeFlags()
-		expect[GRPCDatabrokerKeepalive] = !expect[GRPCDatabrokerKeepalive]
-
-		err = decoder.Decode(map[string]interface{}{
-			"something_else": map[string]bool{
-				"hello": true,
-			},
-			"runtime_flags": map[string]interface{}{
-				string(GRPCDatabrokerKeepalive): expect[GRPCDatabrokerKeepalive],
-			},
-		})
-		assert.NoError(t, err)
-		assert.Equal(t, expect, withMap.RuntimeFlags)
-	})
-
-	t.Run("dont override if unset", func(t *testing.T) {
-		t.Parallel()
-
-		defaults := DefaultRuntimeFlags()
-		withMap := struct {
-			RuntimeFlags RuntimeFlags `mapstructure:"runtime_flags"`
-		}{
-			RuntimeFlags: defaults,
-		}
-
-		decoder, err := mapstructure.NewDecoder(&mapstructure.DecoderConfig{
-			DecodeHook: decodeRuntimeFlagsHookFunc(),
-			Result:     &withMap,
-		})
-		require.NoError(t, err)
-
-		err = decoder.Decode(map[string]interface{}{})
-		assert.NoError(t, err)
-		assert.Equal(t, defaults, withMap.RuntimeFlags)
-	})
-
-	// mapstructure does not correctly wrap errors, so we will have to just search for the error text
-	// https://github.com/mitchellh/mapstructure/blob/ab69d8d93410fce4361f4912bb1ff88110a81311/error.go#L35-L38
-	assertErrorIs := func(t *testing.T, err error, target error) {
-		t.Helper()
-		if assert.Error(t, err) {
-			strings.Contains(err.Error(), target.Error())
-		}
-	}
-
-	t.Run("invalid input", func(t *testing.T) {
-		t.Parallel()
-
-		var withMap struct {
-			RuntimeFlags RuntimeFlags `mapstructure:"runtime_flags"`
-		}
-
-		decoder, err := mapstructure.NewDecoder(&mapstructure.DecoderConfig{
-			DecodeHook: decodeRuntimeFlagsHookFunc(),
-			Result:     &withMap,
-		})
-		require.NoError(t, err)
-
-		err = decoder.Decode(map[string]interface{}{
-			"runtime_flags": "hello world",
-		})
-		assertErrorIs(t, err, ErrRuntimeFlagsInvalidValue)
-
-		err = decoder.Decode(map[string]interface{}{
-			"runtime_flags": map[string]interface{}{
-				"no_such_flag": true,
-			},
-		})
-		assertErrorIs(t, err, ErrRuntimeFlagUnknown)
-
-		err = decoder.Decode(map[string]interface{}{
-			"runtime_flags": map[string]interface{}{
-				string(GRPCDatabrokerKeepalive): "hello world",
-			},
-		})
-		assertErrorIs(t, err, ErrRuntimeFlagInvalidMapValue)
-	})
-}

config/envoyconfig/clusters.go

@@ -79,7 +79,7 @@ func (b *Builder) BuildClusters(ctx context.Context, cfg *config.Config) ([]*env
 		authorizeCluster.OutlierDetection = grpcOutlierDetection()
 	}
 
-	databrokerKeepalive := Keepalive(cfg.Options.IsRuntimeFlagSet(config.GRPCDatabrokerKeepalive))
+	databrokerKeepalive := Keepalive(cfg.Options.IsRuntimeFlagSet(config.RuntimeFlagGRPCDatabrokerKeepalive))
 	databrokerCluster, err := b.buildInternalCluster(ctx, cfg, "pomerium-databroker", databrokerURLs, upstreamProtocolHTTP2, databrokerKeepalive)
 	if err != nil {
 		return nil, err

config/options.go

@@ -389,7 +389,7 @@ func optionsFromViper(configFile string) (*Options, error) {
 	if err := v.Unmarshal(o, ViperPolicyHooks, func(c *mapstructure.DecoderConfig) { c.Metadata = &metadata }); err != nil {
 		return nil, fmt.Errorf("failed to unmarshal config: %w", err)
 	}
-	if err := checkConfigKeysErrors(configFile, metadata.Unused); err != nil {
+	if err := checkConfigKeysErrors(configFile, o, metadata.Unused); err != nil {
 		return nil, err
 	}
 
@@ -402,7 +402,7 @@ func optionsFromViper(configFile string) (*Options, error) {
 	return o, nil
 }
 
-func checkConfigKeysErrors(configFile string, unused []string) error {
+func checkConfigKeysErrors(configFile string, o *Options, unused []string) error {
 	checks := CheckUnknownConfigFields(unused)
 	ctx := context.Background()
 	errInvalidConfigKeys := errors.New("some configuration options are no longer supported, please check logs for details")
@@ -423,6 +423,14 @@ func checkConfigKeysErrors(configFile string, unused []string) error {
 		}
 		evt.Msg(string(check.FieldCheckMsg))
 	}
+
+	// check for unknown runtime flags
+	for flag := range o.RuntimeFlags {
+		if _, ok := defaultRuntimeFlags[flag]; !ok {
+			log.Warn(ctx).Str("config_file", configFile).Str("flag", string(flag)).Msg("unknown runtime flag")
+		}
+	}
+
 	return err
 }
 

config/runtime_flags.go

@@ -1,7 +1,9 @@
 package config
 
-// GRPCDatabrokerKeepalive enables gRPC keepalive to the databroker service
-var GRPCDatabrokerKeepalive = runtimeFlag("grpc_databroker_keepalive", false)
+import "golang.org/x/exp/maps"
+
+// RuntimeFlagGRPCDatabrokerKeepalive enables gRPC keepalive to the databroker service
+var RuntimeFlagGRPCDatabrokerKeepalive = runtimeFlag("grpc_databroker_keepalive", false)
 
 // RuntimeFlag is a runtime flag that can flip on/off certain features
 type RuntimeFlag string
@@ -18,9 +20,5 @@ func runtimeFlag(txt string, def bool) RuntimeFlag {
 var defaultRuntimeFlags = map[RuntimeFlag]bool{}
 
 func DefaultRuntimeFlags() RuntimeFlags {
-	out := make(RuntimeFlags, len(defaultRuntimeFlags))
-	for k, v := range defaultRuntimeFlags {
-		out[k] = v
-	}
-	return out
+	return maps.Clone(defaultRuntimeFlags)
 }