Add dedicated feature flag for breakdown_metrics (#743)

Author: felixbarny

apm-agent-core/src/main/java/co/elastic/apm/agent/configuration/CoreConfiguration.java

@@ -354,6 +354,12 @@ public class CoreConfiguration extends ConfigurationOptionProvider {
             "----\n")
         .buildWithDefault("co.elastic.apm.agent.*");
 
+    private final ConfigurationOption<Boolean> breakdownMetrics = ConfigurationOption.booleanOption()
+        .key("breakdown_metrics")
+        .configurationCategory(CORE_CATEGORY)
+        .description("Disables the collection of breakdown metrics (`span.self_time`)")
+        .buildWithDefault(true);
+
     public boolean isActive() {
         return active.get();
     }
@@ -440,4 +446,8 @@ public TimeDuration getTraceMethodsDurationThreshold() {
     public Map<String, String> getGlobalLabels() {
         return globalLabels.get();
     }
+
+    public boolean isBreakdownMetricsEnabled() {
+        return breakdownMetrics.get();
+    }
 }

apm-agent-core/src/main/java/co/elastic/apm/agent/impl/transaction/AbstractSpan.java

@@ -24,6 +24,7 @@
  */
 package co.elastic.apm.agent.impl.transaction;
 
+import co.elastic.apm.agent.configuration.CoreConfiguration;
 import co.elastic.apm.agent.impl.ElasticApmTracer;
 import co.elastic.apm.agent.impl.context.AbstractContext;
 import co.elastic.apm.agent.matcher.WildcardMatcher;
@@ -117,7 +118,9 @@ public long getDuration() {
     public AbstractSpan(ElasticApmTracer tracer) {
         super(tracer);
         traceContext = TraceContext.with64BitId(this.tracer);
-        collectBreakdownMetrics = !WildcardMatcher.isAnyMatch(tracer.getConfig(ReporterConfiguration.class).getDisableMetrics(), "span.self_time");
+        boolean selfTimeCollectionEnabled = !WildcardMatcher.isAnyMatch(tracer.getConfig(ReporterConfiguration.class).getDisableMetrics(), "span.self_time");
+        boolean breakdownMetricsEnabled = tracer.getConfig(CoreConfiguration.class).isBreakdownMetricsEnabled();
+        collectBreakdownMetrics = selfTimeCollectionEnabled && breakdownMetricsEnabled;
     }
 
     public boolean isReferenced() {

apm-agent-core/src/main/java/co/elastic/apm/agent/report/ReporterConfiguration.java

@@ -162,8 +162,6 @@ public class ReporterConfiguration extends ConfigurationOptionProvider {
             "If the name of a metric matches any of the wildcard expressions, it will not be collected.\n" +
             "Example: `foo.*,bar.*`\n" +
             "\n" +
-            "To disable all breakdown metric collection code paths, add `span.self_time` to the list.\n" +
-            "\n" +
             WildcardMatcher.DOCUMENTATION)
         .dynamic(false)
         .buildWithDefault(Collections.<WildcardMatcher>emptyList());

apm-agent-core/src/test/java/co/elastic/apm/agent/impl/SpanTypeBreakdownTest.java

@@ -26,6 +26,7 @@
 
 import co.elastic.apm.agent.MockReporter;
 import co.elastic.apm.agent.MockTracer;
+import co.elastic.apm.agent.configuration.CoreConfiguration;
 import co.elastic.apm.agent.configuration.SpyConfiguration;
 import co.elastic.apm.agent.impl.sampling.ConstantSampler;
 import co.elastic.apm.agent.impl.transaction.Span;
@@ -43,6 +44,7 @@
 import java.util.Map;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.when;
 
 class SpanTypeBreakdownTest {
 
@@ -73,6 +75,25 @@ void testBreakdown_noSpans() {
         });
     }
 
+    /*
+     * ██████████████████████████████
+     *          10        20        30
+     */
+    @Test
+    void testBreakdown_disabled() {
+        when(tracer.getConfig(CoreConfiguration.class).isBreakdownMetricsEnabled()).thenReturn(false);
+        tracer.startTransaction(TraceContext.asRoot(), null, ConstantSampler.of(true), 0, getClass().getClassLoader())
+            .withName("test")
+            .withType("request")
+            .end(30);
+        tracer.getMetricRegistry().report(metricSets -> {
+            assertThat(getTimer(metricSets, "span.self_time", "app", null)).isNull();
+            assertThat(getTimer(metricSets, "span.self_time", "app", null)).isNull();
+            assertThat(getTimer(metricSets, "transaction.duration", null, null).getTotalTimeUs()).isEqualTo(30);
+            assertThat(metricSets.get(Labels.Mutable.of().transactionName("test").transactionType("request")).getCounters().get("transaction.breakdown.count")).isNull();
+        });
+    }
+
     /*
      * ██████████░░░░░░░░░░██████████
      * └─────────██████████

docs/configuration.asciidoc

@@ -73,6 +73,7 @@ Click on a key to get more information.
 ** <<config-trace-methods>>
 ** <<config-trace-methods-duration-threshold>>
 ** <<config-boot-delegation-packages>>
+** <<config-breakdown-metrics>>
 * <<config-http>>
 ** <<config-capture-body>>
 ** <<config-capture-body-content-types>>
@@ -514,6 +515,26 @@ boot_delegation_packages=org.apache.karaf.jaas.boot, org.apache.karaf.jaas.boot.
 | `elastic.apm.boot_delegation_packages` | `boot_delegation_packages` | `ELASTIC_APM_BOOT_DELEGATION_PACKAGES`
 |============
 
+[float]
+[[config-breakdown-metrics]]
+==== `breakdown_metrics`
+
+Disables the collection of breakdown metrics (`span.self_time`)
+
+
+[options="header"]
+|============
+| Default                          | Type                | Dynamic
+| `true` | Boolean | false
+|============
+
+
+[options="header"]
+|============
+| Java System Properties      | Property file   | Environment
+| `elastic.apm.breakdown_metrics` | `breakdown_metrics` | `ELASTIC_APM_BREAKDOWN_METRICS`
+|============
+
 [[config-http]]
 === HTTP configuration options
 [float]
@@ -1071,8 +1092,6 @@ Disables the collection of certain metrics.
 If the name of a metric matches any of the wildcard expressions, it will not be collected.
 Example: `foo.*,bar.*`
 
-To disable all breakdown metric collection code paths, add `span.self_time` to the list.
-
 This option supports the wildcard `*`, which matches zero or more characters.
 Examples: `/foo/*/bar/*/baz*`, `*foo*`.
 Matching is case insensitive by default.
@@ -1419,6 +1438,14 @@ The default unit for this option is `ms`
 #
 # boot_delegation_packages=co.elastic.apm.agent.*
 
+# Disables the collection of breakdown metrics (`span.self_time`)
+#
+# This setting can not be changed at runtime. Changes require a restart of the application.
+# Type: Boolean
+# Default value: true
+#
+# breakdown_metrics=true
+
 ############################################
 # HTTP                                     #
 ############################################
@@ -1729,8 +1756,6 @@ The default unit for this option is `ms`
 # If the name of a metric matches any of the wildcard expressions, it will not be collected.
 # Example: `foo.*,bar.*`
 # 
-# To disable all breakdown metric collection code paths, add `span.self_time` to the list.
-# 
 # This option supports the wildcard `*`, which matches zero or more characters.
 # Examples: `/foo/*/bar/*/baz*`, `*foo*`.
 # Matching is case insensitive by default.