add config option check logging (#3722)

config/options.go

@@ -11,11 +11,11 @@ import (
 	"os"
 	"path/filepath"
 	"reflect"
-	"regexp"
 	"strings"
 	"time"
 
 	"github.com/mitchellh/mapstructure"
+	"github.com/rs/zerolog"
 	"github.com/spf13/viper"
 	"github.com/volatiletech/null/v9"
 
@@ -374,7 +374,9 @@ 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)
 	}
-	checkUnusedConfigFields(configFile, metadata.Unused)
+	if err := checkConfigKeysErrors(configFile, metadata.Unused); err != nil {
+		return nil, err
+	}
 
 	// This is necessary because v.Unmarshal will overwrite .viper field.
 	o.viper = v
@@ -385,22 +387,28 @@ func optionsFromViper(configFile string) (*Options, error) {
 	return o, nil
 }
 
-var (
-	// policy's embedded protobuf structs are decoded by separate hook and are unknown to mapstructure
-	routesEmbeddedFieldsRe = regexp.MustCompile(`(routes|policy)\[\.*`)
-)
+func checkConfigKeysErrors(configFile string, unused []string) error {
+	checks := CheckUnknownConfigFields(unused)
+	ctx := context.Background()
+	errInvalidConfigKeys := errors.New("some configuration options are no longer supported, please check logs for details")
+	var err error
 
-func checkUnusedConfigFields(configFile string, unused []string) {
-	keys := make([]string, 0, len(unused))
-	for _, k := range unused {
-		if !routesEmbeddedFieldsRe.MatchString(k) {
-			keys = append(keys, k)
+	for _, check := range checks {
+		var evt *zerolog.Event
+		switch check.KeyAction {
+		case KeyActionError:
+			evt = log.Error(ctx)
+			err = errInvalidConfigKeys
+		default:
+			evt = log.Warn(ctx)
 		}
+		evt.Str("config_file", configFile).Str("key", check.Key)
+		if check.DocsURL != "" {
+			evt = evt.Str("help", check.DocsURL)
 		}
-	if len(keys) == 0 {
-		return
+		evt.Msg(string(check.FieldCheckMsg))
 	}
-	log.Warn(context.Background()).Str("config_file", configFile).Strs("keys", keys).Msg("config contained unknown keys that were ignored")
+	return err
 }
 
 // parsePolicy initializes policy to the options from either base64 environmental

config/options_check.go

@@ -0,0 +1,82 @@
+package config
+
+import (
+	"regexp"
+)
+
+// KeyAction defines the Pomerium behavior when it encounters a deprecated config field
+type KeyAction string
+
+// FieldCheckMsg is a log message to print for a config option
+type FieldCheckMsg string
+
+const (
+	// KeyActionWarn would result in warning to log
+	KeyActionWarn = KeyAction("warn")
+	// KeyActionError would result in error in log and possibly program stop
+	KeyActionError = KeyAction("error")
+	// UnknownFieldAction default behavior when observing an unknown field is to warn
+	UnknownFieldAction = KeyActionWarn
+	// FieldCheckMsgRemoved log message when field was removed
+	FieldCheckMsgRemoved = FieldCheckMsg("config option was removed")
+	// FieldCheckMsgUnknown log message for unrecognized / unhandled config option
+	FieldCheckMsgUnknown = FieldCheckMsg("unknown config option")
+)
+
+var reKeyPath = regexp.MustCompile(`\[\d+\]`)
+
+var (
+	// options that were deprecated in the config
+	removedConfigFields = map[string]string{
+		"idp_service_account":            "https://docs.pomerium.com/docs/overview/upgrading#idp-directory-sync",
+		"idp_refresh_directory_timeout":  "https://docs.pomerium.com/docs/overview/upgrading#idp-directory-sync",
+		"idp_refresh_directory_interval": "https://docs.pomerium.com/docs/overview/upgrading#idp-directory-sync",
+		"idp_qps":                        "https://docs.pomerium.com/docs/overview/upgrading#idp-directory-sync",
+		"routes.allowed_groups":          "https://docs.pomerium.com/docs/overview/upgrading#idp-groups-policy",
+	}
+
+	// mapstructure has issues with embedded protobuf structs that we should ignore
+	ignoreConfigFields = map[string]struct{}{
+		"routes.outlier_detection": {},
+		"routes.health_checks":     {},
+	}
+)
+
+// FieldMsg returns information
+type FieldMsg struct {
+	Key     string
+	DocsURL string
+	FieldCheckMsg
+	KeyAction
+}
+
+// CheckUnknownConfigFields returns list of messages to be emitted about unrecognized fields
+func CheckUnknownConfigFields(fields []string) []FieldMsg {
+	out := make([]FieldMsg, 0, len(fields))
+
+	for _, key := range fields {
+		path := reKeyPath.ReplaceAllString(key, "")
+
+		if docsURL, ok := removedConfigFields[path]; ok {
+			out = append(out, FieldMsg{
+				Key:           path,
+				DocsURL:       docsURL,
+				KeyAction:     KeyActionError,
+				FieldCheckMsg: FieldCheckMsgRemoved,
+			})
+			continue
+		}
+
+		if _, ok := ignoreConfigFields[path]; ok {
+			continue
+		}
+
+		out = append(out, FieldMsg{
+			Key:           path,
+			KeyAction:     KeyActionWarn,
+			FieldCheckMsg: FieldCheckMsgUnknown,
+		})
+	}
+
+	return out
+}