add NoOpSender (#273)

Author: Oseenix

build/src/main/resources/agent.properties

@@ -36,9 +36,18 @@ plugin.observability.global.metric.enabled=true
 plugin.observability.global.metric.interval=30
 plugin.observability.global.metric.topic=application-metrics
 plugin.observability.global.metric.url=/application-metrics
+
+## 
+# if different with reporter.outputServer.appendType,
+# following options can be used in user config file to override
+# the default or global one
+#
+## when it's scrape by prometheus, noop can be used
+# plugin.observability.global.metric.appendType=noop
+## for debug, console can be used
 # plugin.observability.global.metric.appendType=console
-## output by http
-#plugin.observability.global.metric.appendType=http
+# plugin.observability.global.metric.appendType=http
+#
 # add service name to header enabled by name for easemesh
 plugin.integrability.global.addServiceNameHead.enabled=true
 # redirect the middleware address when env has address, see: com.megaease.easeagent.plugin.api.middleware.RedirectProcessor

config/src/main/java/com/megaease/easeagent/config/report/ReportConfigConst.java

@@ -26,6 +26,8 @@ private ReportConfigConst() {}
     public static final String CONSOLE_SENDER_NAME = "console";
     public static final String ZIPKIN_SENDER_NAME = "http";
 
+    public static final String NOOP_SENDER_NAME = "noop";
+
     public static final String SPAN_JSON_ENCODER_NAME = "SpanJsonEncoder";
     public static final String METRIC_JSON_ENCODER_NAME = "MetricJsonEncoder";
     public static final String LOG_DATA_JSON_ENCODER_NAME = "LogDataJsonEncoder";

doc/images/grafana-tracing.png

@@ -17,6 +17,8 @@
  */
 package com.megaease.easeagent.report.sender;
 
+import com.google.auto.service.AutoService;
+import com.megaease.easeagent.config.report.ReportConfigConst;
 import com.megaease.easeagent.plugin.api.config.Config;
 import com.megaease.easeagent.plugin.report.Call;
 import com.megaease.easeagent.plugin.report.EncodedData;
@@ -26,12 +28,13 @@
 import java.io.IOException;
 import java.util.Map;
 
+@AutoService(Sender.class)
 public class NoOpSender implements Sender {
     public static final NoOpSender INSTANCE = new NoOpSender();
 
     @Override
     public String name() {
-        return "noop";
+        return ReportConfigConst.NOOP_SENDER_NAME;
     }
 
     @Override
@@ -41,12 +44,12 @@ public void init(Config config, String prefix) {
 
     @Override
     public Call<Void> send(EncodedData encodedData) {
-        return new NoOpCall<>();
+        return NoOpCall.getInstance(NoOpSender.class);
     }
 
     @Override
     public boolean isAvailable() {
-        return false;
+        return true;
     }
 
     @Override