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opentelemetry-java-instrumentation
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Define the concept of applicationRootSpanTags and apply only to root 

tags
This commit is contained in:
Luca Abbati 2019-05-16 12:25:43 +02:00
parent 0e9f9d9d02
commit 10069847a3
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GPG Key ID: C901DDA2FFE14529
4 changed files with 107 additions and 106 deletions
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50
dd-trace-api/src/main/java/datadog/trace/api/Config.java
View File

@ -1,5 +1,7 @@
package datadog.trace.api;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
@ -113,6 +115,9 @@ public class Config {
B3
}
/** A tag intended for internal use only, hence not added to the public api DDTags class. */
private static final String INTERNAL_HOST_NAME = "_dd.hostname";
/**
* this is a random UUID that gets generated on JVM start up and is attached to every root span
* and every JMX metric that is sent out.
@ -150,10 +155,7 @@ public class Config {
@Getter private final boolean logsInjectionEnabled;
// If `true` the hostname will be detected and added to the root span's metadata
// Note: this temporarily non final as a conversation is in place related to how to improve
// testability under different configuration scenarios.
@Getter private boolean reportHostName;
@Getter private final boolean reportHostName;
// Read order: System Properties -> Env Variables, [-> default value]
// Visible for testing
@ -318,6 +320,15 @@ public class Config {
log.debug("New instance: {}", this);
}
/** @return A map of tags to be applied only to the currently tracing application root span. */
public Map<String, String> getApplicationRootSpanTags() {
final Map<String, String> result = newHashMap(reportHostName ? 1 : 0);
if (reportHostName) {
result.put(INTERNAL_HOST_NAME, getHostname());
}
return Collections.unmodifiableMap(result);
}
public Map<String, String> getMergedSpanTags() {
// DO not include runtimeId into span tags: we only want that added to the root span
final Map<String, String> result = newHashMap(globalTags.size() + spanTags.size());
@ -646,6 +657,28 @@ public class Config {
return Collections.unmodifiableSet(result);
}
// Fields used to cache detected hostName which is a time consuming operation.
private String hostName = null;
private boolean hostNameDetected = false;
/**
* Returns the detected hostname. This operation is time consuming and the first time this method
* is called will take some time. Hostname is cached for subsequent calls.
*/
public String getHostname() {
if (!this.hostNameDetected) {
try {
this.hostName = InetAddress.getLocalHost().getHostName();
} catch (UnknownHostException e) {
// If we are not able to detect the hostname we do not throw an exception.
} finally {
this.hostNameDetected = true;
}
}
return this.hostName;
}
// This has to be placed after all other static fields to give them a chance to initialize
private static final Config INSTANCE = new Config();
@ -660,13 +693,4 @@ public class Config {
return new Config(properties, INSTANCE);
}
}
/**
* Note: this is a workaround as a conversation related to improve testability of services under
* different configuration scenarios is in progress.
*/
public void refreshDetectHostnameProperty() {
this.reportHostName =
getBooleanSettingFromEnvironment(TRACE_REPORT_HOSTNAME, DEFAULT_TRACE_REPORT_HOSTNAME);
}
}

23
dd-trace-api/src/test/groovy/datadog/trace/api/ConfigTest.groovy
View File

@ -658,4 +658,27 @@ class ConfigTest extends Specification {
listString | list
"" | []
}
def "verify hostname not added to root span tags by default"() {
setup:
Properties properties = new Properties()
when:
def config = Config.get(properties)
then:
!config.applicationRootSpanTags.containsKey('_dd.hostname')
}
def "verify configuration to add hostname to root span tags"() {
setup:
Properties properties = new Properties()
properties.setProperty(TRACE_REPORT_HOSTNAME, 'true')
when:
def config = Config.get(properties)
then:
config.applicationRootSpanTags.get('_dd.hostname') == InetAddress.localHost.hostName
}
}

105
dd-trace-ot/src/main/java/datadog/opentracing/DDTracer.java
View File

@ -26,8 +26,6 @@ import io.opentracing.propagation.Format;
import io.opentracing.propagation.TextMap;
import java.io.Closeable;
import java.lang.ref.WeakReference;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentSkipListSet;
@ -50,6 +48,8 @@ public class DDTracer implements io.opentracing.Tracer, Closeable, datadog.trace
/** Tags required to link apm traces to runtime metrics */
final Map<String, String> runtimeTags;
/** A set of tags that are added only to the application's root span */
private final Map<String, String> applicationRootSpanTags;
/** A set of tags that are added to every span */
private final Map<String, String> defaultSpanTags;
/** A configured mapping of service names to update with new values */
@ -80,15 +80,6 @@ public class DDTracer implements io.opentracing.Tracer, Closeable, datadog.trace
private final HttpCodec.Injector injector;
private final HttpCodec.Extractor extractor;
/** A tag intended for internal use only, hence not added to the public api DDTags class. */
private static final String INTERNAL_HOST_NAME = "_dd.hostname";
/**
* hostname is expensive to calculate so we detect it only when creating the tracer and we cache
* it for future reuse.
*/
private String hostname;
/** By default, report to local agent and collect all traces. */
public DDTracer() {
this(Config.get());
@ -117,6 +108,7 @@ public class DDTracer implements io.opentracing.Tracer, Closeable, datadog.trace
Writer.Builder.forConfig(config),
Sampler.Builder.forConfig(config),
config.getRuntimeTags(),
config.getApplicationRootSpanTags(),
config.getMergedSpanTags(),
config.getServiceMapping(),
config.getHeaderTags(),
@ -138,6 +130,7 @@ public class DDTracer implements io.opentracing.Tracer, Closeable, datadog.trace
Collections.<String, String>emptyMap(),
Collections.<String, String>emptyMap(),
Collections.<String, String>emptyMap(),
Collections.<String, String>emptyMap(),
0);
}
@ -151,6 +144,7 @@ public class DDTracer implements io.opentracing.Tracer, Closeable, datadog.trace
writer,
Sampler.Builder.forConfig(config),
config.getRuntimeTags(),
config.getApplicationRootSpanTags(),
config.getMergedSpanTags(),
config.getServiceMapping(),
config.getHeaderTags(),
@ -166,6 +160,7 @@ public class DDTracer implements io.opentracing.Tracer, Closeable, datadog.trace
final Writer writer,
final Sampler sampler,
final String runtimeId,
final Map<String, String> applicationRootSpanTags,
final Map<String, String> defaultSpanTags,
final Map<String, String> serviceNameMappings,
final Map<String, String> taggedHeaders) {
@ -174,6 +169,7 @@ public class DDTracer implements io.opentracing.Tracer, Closeable, datadog.trace
writer,
sampler,
customRuntimeTags(runtimeId),
applicationRootSpanTags,
defaultSpanTags,
serviceNameMappings,
taggedHeaders,
@ -189,6 +185,7 @@ public class DDTracer implements io.opentracing.Tracer, Closeable, datadog.trace
final Writer writer,
final Sampler sampler,
final Map<String, String> runtimeTags,
final Map<String, String> applicationRootSpanTags,
final Map<String, String> defaultSpanTags,
final Map<String, String> serviceNameMappings,
final Map<String, String> taggedHeaders) {
@ -197,6 +194,7 @@ public class DDTracer implements io.opentracing.Tracer, Closeable, datadog.trace
writer,
sampler,
runtimeTags,
applicationRootSpanTags,
defaultSpanTags,
serviceNameMappings,
taggedHeaders,
@ -208,6 +206,7 @@ public class DDTracer implements io.opentracing.Tracer, Closeable, datadog.trace
final Writer writer,
final Sampler sampler,
final Map<String, String> runtimeTags,
final Map<String, String> applicationRootSpanTags,
final Map<String, String> defaultSpanTags,
final Map<String, String> serviceNameMappings,
final Map<String, String> taggedHeaders,
@ -221,6 +220,7 @@ public class DDTracer implements io.opentracing.Tracer, Closeable, datadog.trace
this.writer = writer;
this.writer.start();
this.sampler = sampler;
this.applicationRootSpanTags = applicationRootSpanTags;
this.defaultSpanTags = defaultSpanTags;
this.runtimeTags = runtimeTags;
this.serviceNameMappings = serviceNameMappings;
@ -256,8 +256,6 @@ public class DDTracer implements io.opentracing.Tracer, Closeable, datadog.trace
// Ensure that PendingTrace.SPAN_CLEANER is initialized in this thread:
// FIXME: add test to verify the span cleaner thread is started with this call.
PendingTrace.initialize();
cacheHostName();
}
@Override
@ -383,7 +381,6 @@ public class DDTracer implements io.opentracing.Tracer, Closeable, datadog.trace
// TODO: current trace implementation doesn't guarantee that first span is the root span
// We may want to reconsider way this check is done.
if (!writtenTrace.isEmpty() && sampler.sample(writtenTrace.get(0))) {
applyHostNameDetection(writtenTrace);
writer.write(writtenTrace);
}
}
@ -616,6 +613,7 @@ public class DDTracer implements io.opentracing.Tracer, Closeable, datadog.trace
final PendingTrace parentTrace;
final int samplingPriority;
final String origin;
final boolean isApplicationRootSpan = parent == null || !(parent instanceof DDSpanContext);
final DDSpanContext context;
SpanContext parentContext = parent;
@ -678,6 +676,10 @@ public class DDTracer implements io.opentracing.Tracer, Closeable, datadog.trace
final String operationName = this.operationName != null ? this.operationName : resourceName;
if (isApplicationRootSpan) {
applyTagsIfNotDefined(tags, applicationRootSpanTags);
}
// some attributes are inherited from the parent
context =
new DDSpanContext(
@ -727,6 +729,28 @@ public class DDTracer implements io.opentracing.Tracer, Closeable, datadog.trace
return context;
}
/**
* Merge a map of tag 'candidates' into a 'destination' map of tags never overwriting original
* values.
*
* @param destination The map of tags where candidate tags will be merged in
* @param candidates The potential tags that will be added if not already defined
*/
private void applyTagsIfNotDefined(
Map<String, Object> destination, Map<String, String> candidates) {
if (null == destination || null == candidates) {
return;
}
for (Map.Entry<String, String> entry : candidates.entrySet()) {
if (destination.containsKey(entry.getKey())) {
continue;
}
destination.put(entry.getKey(), entry.getValue());
}
}
}
private static class ShutdownHook extends Thread {
@ -744,57 +768,4 @@ public class DDTracer implements io.opentracing.Tracer, Closeable, datadog.trace
}
}
}
/**
* Hostname is expensive to retrieve so we provide a way to calculate it and cache it in the
* tracer itself for further reuse.
*/
private void cacheHostName() {
// Host name detection can be disabled via configuration
if (!Config.get().isReportHostName()) {
return;
}
try {
this.hostname = InetAddress.getLocalHost().getHostName();
} catch (UnknownHostException e) {
// If we are not able to detect the hostname we do not throw an exception.
}
}
/**
* Sets the internal hostname tag on a root span if appropriate. The following acceptance criteria
* apply: 1) Users should not be able to overwrite this value, 2) It has to be done only on the
* root span, 3) It is not guaranteed that the first span in the list is the root span.
*
* @param spans
*/
private void applyHostNameDetection(List<DDSpan> spans) {
// Host name detection can be disabled via configuration
if (!Config.get().isReportHostName()) {
return;
}
// Every time we set a tag all the decorators have to be executed so if we already set the
// hostname on the root of a specific span, using this registry we can avoid setting the tag
// again, hence executing all decorators again to obtain the same result.
Set<MutableSpan> alreadyTrackedRootSpans = new HashSet<>();
for (DDSpan span : spans) {
MutableSpan rootSpan = span.getRootSpan();
// Only root spans get the hostname applied
if (null == rootSpan) {
continue;
}
if (alreadyTrackedRootSpans.contains(rootSpan)) {
continue;
}
alreadyTrackedRootSpans.add(rootSpan);
rootSpan.setTag(INTERNAL_HOST_NAME, hostname);
}
}
}

35
dd-trace-ot/src/test/groovy/datadog/trace/DDTracerTest.groovy
View File

@ -149,35 +149,18 @@ class DDTracerTest extends Specification {
PRIORITY_SAMPLING | "false"
}
def "tracer does not set the host name by default"() {
def "root tags are applied only to root spans"() {
setup:
def tracer = new DDTracer('my_service', new ListWriter(), new AllSampler())
def tracer = new DDTracer('my_service', new ListWriter(), new AllSampler(), '', ['only_root': 'value'], [:], [:], [:])
def root = tracer.buildSpan('my_root').start()
def child = tracer.buildSpan('my_child').asChildOf(root).start()
when:
DDSpan root = tracer.buildSpan('my_root').start()
DDSpan child = tracer.buildSpan('my_child').asChildOf(root).start()
expect:
root.context().tags.containsKey('only_root')
!child.context().tags.containsKey('only_root')
cleanup:
child.finish()
root.finish()
then:
!root.context().tags.containsKey(INTERNAL_HOST_NAME)
!child.context().tags.containsKey(INTERNAL_HOST_NAME)
}
def "tracer sets the host name if activated only on root span"() {
setup:
System.setProperty('dd.trace.report-hostname', 'true')
Config.get().refreshDetectHostnameProperty()
def tracer = new DDTracer('my_service', new ListWriter(), new AllSampler())
when:
DDSpan root = tracer.buildSpan('my_root').start()
DDSpan child = tracer.buildSpan('my_child').asChildOf(root).start()
child.finish()
root.finish()
then:
root.context().tags.get(INTERNAL_HOST_NAME) == InetAddress.localHost.hostName
!child.context().tags.containsKey(INTERNAL_HOST_NAME)
}
}