Allow setting different log levels for log categories/tags

jobs/bosh-dns/spec

@@ -174,3 +174,6 @@ properties:
   logging.format.timestamp:
     description: "Format for the timestamp in the component logs.  Valid values are 'rfc3339' and 'deprecated'."
     default: "rfc3339"
+
+  logging.categories:
+      description: "Categories for logging to provide individual configuration to the logger."

jobs/bosh-dns/templates/config.json.erb

@@ -46,7 +46,8 @@
   logging: {
     format: {
       timestamp: p('logging.format.timestamp')
-    }
+    },
+    categories: p('logging.categories')
   }
 }.to_json
 %>

src/bosh-dns/dns/config/config.go

@@ -54,6 +54,22 @@ func (c Config) GetLogLevel() (boshlog.LogLevel, error) {
 	return level, nil
 }
 
+func (c Config) GetLogCategories() []boshlog.LogCategory {
+	var categories []boshlog.LogCategory
+
+	for _, category := range c.Logging.Categories {
+		loggerLevelValue, err := boshlog.Levelify(category.LogLevel)
+		if err != nil {
+			continue
+		}
+		categories = append(categories, boshlog.LogCategory{
+			Name:     category.Name,
+			LogLevel: loggerLevelValue,
+		})
+	}
+	return categories
+}
+
 func (c Config) UseRFC3339Formatting() bool {
 	return strings.EqualFold(c.Logging.Format.TimeStamp, RFCFormatting)
 }
@@ -91,8 +107,14 @@ type InternalUpcheckDomain struct {
 	DNSQuery string `json:"dns_query"`
 }
 
+type LogCategory struct {
+	Name     string `json:"name"`
+	LogLevel string `json:"log_level"`
+}
+
 type LoggingConfig struct {
-	Format FormatConfig `json:"format,omitempty"`
+	Format     FormatConfig  `json:"format,omitempty"`
+	Categories []LogCategory `json:"categories,omitempty"`
 }
 
 type FormatConfig struct {

src/bosh-dns/dns/main.go

@@ -78,6 +78,7 @@ func mainExitCode() int {
 	if config.UseRFC3339Formatting() {
 		logger.UseRFC3339Timestamps()
 	}
+	logger.UseCategories(config.GetLogCategories())
 	logTag := "main"
 	logger.Info(logTag, "bosh-dns starting")
 	defer logger.FlushTimeout(5 * time.Second) //nolint:errcheck