Log type metrics (#1018)

* Add event log type to metrics

* lint

* PR Feedback

Source/santad/SNTApplicationCoreMetrics.mm

@@ -47,6 +47,29 @@ static void RegisterModeMetric(SNTMetricSet *metricSet) {
   }];
 }
 
+/**
+ * Register the event log type metric checking the config before reporting the status.
+ */
+static void RegisterEventLogType(SNTMetricSet *metricSet) {
+  SNTMetricStringGauge *logType = [metricSet stringGaugeWithName:@"/santa/log_type"
+                                                      fieldNames:@[]
+                                                        helpText:@"Santa's log type"];
+
+  // create a callback that gets the current log type
+  [metricSet registerCallback:^{
+    switch ([[SNTConfigurator configurator] eventLogType]) {
+      case SNTEventLogTypeProtobuf: [logType set:@"protobuf" forFieldValues:@[]]; break;
+      case SNTEventLogTypeSyslog: [logType set:@"syslog" forFieldValues:@[]]; break;
+      case SNTEventLogTypeNull: [logType set:@"null" forFieldValues:@[]]; break;
+      case SNTEventLogTypeFilelog: [logType set:@"file" forFieldValues:@[]]; break;
+      default:
+        // Should never be reached.
+        [logType set:@"unknown" forFieldValues:@[]];
+        break;
+    }
+  }];
+}
+
 /**
  * Register metrics for measuring memory usage.
  */
@@ -129,6 +152,7 @@ static void RegisterCommonSantaMetrics(SNTMetricSet *metricSet) {
                                  value:[SNTSystemInfo osVersion]];
 
   RegisterModeMetric(metricSet);
+  RegisterEventLogType(metricSet);
   // TODO(markowsky) Register CSR status
   // TODO(markowsky) Register system extension status
 }

Source/santad/SNTApplicationCoreMetricsTest.mm

@@ -80,6 +80,7 @@
 - (void)testRegisteringCoreMetrics {
   OCMStub([self.mockConfigurator extraMetricLabels]).andReturn(self.extraMetricLabels);
   OCMStub([self.mockConfigurator clientMode]).andReturn(SNTClientModeLockdown);
+  OCMStub([self.mockConfigurator eventLogType]).andReturn(SNTEventLogTypeProtobuf);
 
   SNTRegisterCoreMetrics();
 
@@ -191,6 +192,18 @@
           } ],
         },
       },
+      @"/santa/log_type" : @{
+        @"description" : @"Santa's log type",
+        @"type" : @6,
+        @"fields" : @{
+          @"" : @[ @{
+            @"created" : fixedDate,
+            @"data" : @"protobuf",
+            @"last_updated" : fixedDate,
+            @"value" : @""
+          } ],
+        },
+      },
     },
     @"root_labels" : @{
       @"host_name" : hostname,