Add OpenTelemetry tracing instrumentation to API layer

Add OTel annotations and API dependencies to enable distributed tracing
of CloudStack API requests. The @WithSpan annotation on handleRequest()
tags each trace with the API command name (e.g. listVirtualMachines),
making it possible to filter and analyze per-command latency. The OTel
agent auto-instruments JDBC and HTTP calls, providing full request
waterfalls with no additional code changes.

All instrumentation is inert without the OTel Java agent attached:
@WithSpan is ignored, Span.current() returns a no-op, and the
opentelemetry-api calls return immediately with zero overhead.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: 2 people

api/pom.xml

@@ -71,6 +71,11 @@
             <artifactId>cloud-framework-direct-download</artifactId>
             <version>${project.version}</version>
         </dependency>
+        <dependency>
+            <groupId>io.opentelemetry.instrumentation</groupId>
+            <artifactId>opentelemetry-instrumentation-annotations</artifactId>
+            <version>2.16.0</version>
+        </dependency>
     </dependencies>
     <build>
         <plugins>

server/pom.xml

@@ -197,6 +197,16 @@
             <version>4.22.1.0-SNAPSHOT</version>
             <scope>compile</scope>
         </dependency>
+        <dependency>
+            <groupId>io.opentelemetry.instrumentation</groupId>
+            <artifactId>opentelemetry-instrumentation-annotations</artifactId>
+            <version>2.16.0</version>
+        </dependency>
+        <dependency>
+            <groupId>io.opentelemetry</groupId>
+            <artifactId>opentelemetry-api</artifactId>
+            <version>1.51.0</version>
+        </dependency>
     </dependencies>
     <build>
         <plugins>

server/src/main/java/com/cloud/api/ApiServer.java

@@ -58,6 +58,9 @@
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpSession;
 
+import io.opentelemetry.api.trace.Span;
+import io.opentelemetry.instrumentation.annotations.WithSpan;
+
 import com.cloud.cluster.ManagementServerHostVO;
 import com.cloud.cluster.dao.ManagementServerHostDao;
 import com.cloud.user.Account;
@@ -619,6 +622,7 @@ public void checkCharacterInkParams(final Map params) {
     }
 
     @Override
+    @WithSpan("ApiServer.handleRequest")
     @SuppressWarnings("rawtypes")
     public String handleRequest(final Map params, final String responseType, final StringBuilder auditTrailSb) throws ServerApiException {
         checkCharacterInkParams(params);
@@ -628,6 +632,10 @@ public String handleRequest(final Map params, final String responseType, final S
 
         try {
             command = (String[])params.get("command");
+            if (command != null && command.length > 0) {
+                Span.current().updateName("ApiServer.handleRequest " + command[0]);
+                Span.current().setAttribute("api.command", command[0]);
+            }
             if (command == null) {
                 logger.error("invalid request, no command sent");
                 if (logger.isTraceEnabled()) {

tools/docker/supervisord.conf

@@ -12,6 +12,7 @@ command=/bin/bash -c "mvn -pl client jetty:run -Dsimulator -Dorg.eclipse.jetty.a
 directory=/root
 stdout_logfile=/dev/stdout
 stdout_logfile_maxbytes=0
+redirect_stderr=true
 user=root
 
 [program:cloudstack-ui]