fix(backend): workaround viper map key parsing

This is a workaround until this issue is fixed upstream.

Fixes #507

internal/config/config.go

@@ -3,6 +3,7 @@ package config
 import (
 	"bufio"
 	"bytes"
+	"io/ioutil"
 	"os"
 	"strings"
 	"time"
@@ -184,6 +185,28 @@ func (config *configSchema) Read() {
 		log.Fatalf("Invalid grid.sorting.order value '%s', allowed options: disabled, startsAt, label", config.Grid.Sorting.Order)
 	}
 
+	// FIXME workaround  for https://github.com/prymitive/karma/issues/507
+	// until https://github.com/spf13/viper/pull/635 is merged
+	// read in raw config file if it's used and override maps where keys are label
+	// names so we can't enforce parsed config key names
+	if v.ConfigFileUsed() != "" {
+		raw := configSchema{}
+
+		var rawConfigFile []byte
+		rawConfigFile, err = ioutil.ReadFile(v.ConfigFileUsed())
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		err = yaml.Unmarshal(rawConfigFile, &raw)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		config.Labels.Color.Custom = raw.Labels.Color.Custom
+		config.Grid.Sorting.CustomValues.Labels = raw.Grid.Sorting.CustomValues.Labels
+	}
+
 	// accept single Alertmanager server from flag/env if nothing is set yet
 	if len(config.Alertmanager.Servers) == 0 && v.GetString("alertmanager.uri") != "" {
 		log.Info("Using simple config with a single Alertmanager server")