Initial release

.gitignore

@@ -0,0 +1,2 @@
+/target/
+/.mvn/wrapper/maven-wrapper.jar

.idea/.gitignore

@@ -0,0 +1,10 @@
+# Default ignored files
+/shelf/
+/workspace.xml
+# Editor-based HTTP Client requests
+/httpRequests/
+# Ignored default folder with query files
+/queries/
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml

.idea/compiler.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="CompilerConfiguration">
+    <annotationProcessing>
+      <profile name="Maven default annotation processors profile" enabled="true">
+        <sourceOutputDir name="target/generated-sources/annotations" />
+        <sourceTestOutputDir name="target/generated-test-sources/test-annotations" />
+        <outputRelativeToContentRoot value="true" />
+        <module name="otel-quarkus-demo" />
+      </profile>
+    </annotationProcessing>
+  </component>
+</project>

.idea/encodings.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="Encoding">
+    <file url="file://$PROJECT_DIR$/src/main/java" charset="UTF-8" />
+    <file url="file://$PROJECT_DIR$/src/main/resources" charset="UTF-8" />
+  </component>
+</project>

.idea/jarRepositories.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="RemoteRepositoriesConfiguration">
+    <remote-repository>
+      <option name="id" value="central" />
+      <option name="name" value="Central Repository" />
+      <option name="url" value="https://repo.maven.apache.org/maven2" />
+    </remote-repository>
+    <remote-repository>
+      <option name="id" value="central" />
+      <option name="name" value="Maven Central repository" />
+      <option name="url" value="https://repo1.maven.org/maven2" />
+    </remote-repository>
+    <remote-repository>
+      <option name="id" value="jboss.community" />
+      <option name="name" value="JBoss Community repository" />
+      <option name="url" value="https://repository.jboss.org/nexus/content/repositories/public/" />
+    </remote-repository>
+  </component>
+</project>

.idea/misc.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ExternalStorageConfigurationManager" enabled="true" />
+  <component name="MavenProjectsManager">
+    <option name="originalFiles">
+      <list>
+        <option value="$PROJECT_DIR$/pom.xml" />
+      </list>
+    </option>
+  </component>
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_25" default="true" project-jdk-name="25" project-jdk-type="JavaSDK" />
+</project>

.idea/vcs.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+  </component>
+</project>

.mvn/wrapper/maven-wrapper.properties

@@ -0,0 +1,2 @@
+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.9/apache-maven-3.9.9-bin.zip
+wrapperUrl=https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/3.3.2/maven-wrapper-3.3.2.jar

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project
+
+Quarkus 3.35 / Java 21 demo app (`otel-quarkus-demo`) that exercises a full observability stack: OpenTelemetry traces/metrics/logs via OTLP, Micrometer with both a Prometheus scrape endpoint and an OTLP push exporter, structured JSON logging, and SmallRye health checks. The OTLP endpoints in `application.properties` point at an in-cluster collector (`otel-collector-opentelemetry-collector.observability.svc.cluster.local`) — running locally without that collector means OTLP exporters will fail, but the app still serves requests and exposes `/q/metrics`.
+
+## Commands
+
+Use the Maven wrapper (`./mvnw`) — there is no `mvn` requirement.
+
+- Dev mode (hot reload, dev UI at `/q/dev`): `./mvnw quarkus:dev`
+- Build runnable app (fast-jar layout in `target/quarkus-app/`): `./mvnw package`
+- Build container image (jib): `./mvnw package -Dquarkus.container-image.build=true`
+- Run packaged app: `java -jar target/quarkus-app/quarkus-run.jar`
+- Tests: `./mvnw test` (no tests exist yet; surefire/failsafe are configured via the Quarkus BOM)
+- Single test once added: `./mvnw test -Dtest=ClassName#methodName`
+
+The app listens on `:8080`. Key endpoints: `POST /api/orders`, `GET /api/orders`, `GET /api/orders/{id}`, `GET /api/inventory`, `GET /q/health`, `GET /q/metrics`.
+
+## Architecture
+
+Three classes under `src/main/java/com/demo/`, all part of a single REST surface:
+
+- `OrderResource` — JAX-RS resource at `/api`. Every request path manually builds a parent span (`processOrder`) and child spans (`validateOrder`, `checkInventory`, `processPayment`) using the injected OTel `Tracer`, sets span attributes, and records status/exceptions explicitly. It also lazily registers Micrometer meters (`orders` counter tagged by status, `orders_amount` counter, `order_processing_duration` timer with percentiles, `order_item_count` summary) on each call — the registry deduplicates, but be aware that meter definitions live alongside the request handler rather than in a separate config class. Two behaviors are intentional for demo signal: `Thread.sleep` calls simulate latency, and ~10% of orders throw a synthetic `RuntimeException` to generate error traces.
+- `InventoryService` — `@ApplicationScoped` CDI bean. Seeds six products on `@PostConstruct` and registers one `inventory_level` Micrometer gauge per product (tagged `product=...`) bound to an `AtomicInteger`. Decrementing below 10 auto-restocks by 100 — keep this in mind when interpreting metric dips.
+- `Order` — DTO with auto-generated id and computed `totalPrice`. The in-memory order store lives on `OrderResource` as a `CopyOnWriteArrayList` (non-persistent; cleared on restart).
+
+Observability wiring is entirely in `application.properties`:
+- OTLP traces/metrics/logs are exported to the collector via gRPC on `:4317`, plus a parallel HTTP push of Micrometer metrics to `:4318/v1/metrics`. Both are configured — changing one without the other leaves a divergent metrics pipeline.
+- The trace sampler is `always_on` (demo only — switch to ratio-based in any real deployment).
+- Console log format embeds `traceId`/`spanId` from MDC; `quarkus.log.console.json.enabled=false` despite the `quarkus-logging-json` dependency being present (toggle it on for Loki-friendly output).
+
+## Conventions worth knowing
+
+- Span lifecycle in `OrderResource` is manual (`spanBuilder().startSpan()` + `try/finally span.end()`). When adding new endpoints, follow the same pattern rather than relying on `@WithSpan` so attributes/status handling stays consistent.
+- Meter names use snake_case (`orders_amount`, `order_processing_duration`, `inventory_level`); tags use snake_case too (`order.product`, `inventory.in_stock`). Match this when adding metrics so dashboards/PromQL stay uniform.
+- The Dockerfile is a two-stage Maven → JRE-alpine build that copies the `target/quarkus-app/` fast-jar layout — `./mvnw package` must succeed before `docker build` will work.

Dockerfile

@@ -0,0 +1,21 @@
+# ── Stage 1: Build ───────────────────────────────────────────
+FROM maven:3.9-eclipse-temurin-21-alpine AS build
+WORKDIR /app
+COPY pom.xml .
+RUN mvn dependency:go-offline -B
+COPY src ./src
+RUN mvn package -DskipTests -B
+
+# ── Stage 2: Runtime ─────────────────────────────────────────
+FROM eclipse-temurin:21-jre-alpine
+WORKDIR /app
+
+RUN addgroup -S quarkus && adduser -S quarkus -G quarkus
+COPY --from=build /app/target/quarkus-app/ ./
+
+USER quarkus
+EXPOSE 8080
+
+ENV JAVA_OPTS="-Dquarkus.http.host=0.0.0.0"
+
+ENTRYPOINT ["java", "-jar", "quarkus-run.jar"]

k3s/deployment.yaml

@@ -0,0 +1,16 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata: { name: otel-quarkus-demo }
+spec:
+  replicas: 1
+  selector: { matchLabels: { app: otel-quarkus-demo } }
+  template:
+    metadata: { labels: { app: otel-quarkus-demo } }
+    spec:
+      containers:
+      - name: app
+        image: rm.vdi-linux-cvl.local/global/quarkus-app:latest
+        imagePullPolicy: IfNotPresent
+        ports: [{ containerPort: 8080 }]
+        readinessProbe: { httpGet: { path: /q/health/ready, port: 8080 } }
+        livenessProbe:  { httpGet: { path: /q/health/live,  port: 8080 } }

k3s/service.yaml

@@ -0,0 +1,6 @@
+apiVersion: v1
+kind: Service
+metadata: { name: otel-quarkus-demo }
+spec:
+  selector: { app: otel-quarkus-demo }
+  ports: [{ port: 8080, targetPort: 8080 }]

mvnw

@@ -0,0 +1,332 @@
+#!/bin/sh
+# ----------------------------------------------------------------------------
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+# ----------------------------------------------------------------------------
+
+# ----------------------------------------------------------------------------
+# Apache Maven Wrapper startup batch script, version @@project.version@@
+#
+# Required ENV vars:
+# ------------------
+#   JAVA_HOME - location of a JDK home dir
+#
+# Optional ENV vars
+# -----------------
+#   MAVEN_OPTS - parameters passed to the Java VM when running Maven
+#     e.g. to debug Maven itself, use
+#       set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000
+#   MAVEN_SKIP_RC - flag to disable loading of mavenrc files
+# ----------------------------------------------------------------------------
+
+if [ -z "$MAVEN_SKIP_RC" ]; then
+
+  if [ -f /usr/local/etc/mavenrc ]; then
+    . /usr/local/etc/mavenrc
+  fi
+
+  if [ -f /etc/mavenrc ]; then
+    . /etc/mavenrc
+  fi
+
+  if [ -f "$HOME/.mavenrc" ]; then
+    . "$HOME/.mavenrc"
+  fi
+
+fi
+
+# OS specific support.  $var _must_ be set to either true or false.
+cygwin=false
+darwin=false
+mingw=false
+case "$(uname)" in
+CYGWIN*) cygwin=true ;;
+MINGW*) mingw=true ;;
+Darwin*)
+  darwin=true
+  # Use /usr/libexec/java_home if available, otherwise fall back to /Library/Java/Home
+  # See https://developer.apple.com/library/mac/qa/qa1170/_index.html
+  if [ -z "$JAVA_HOME" ]; then
+    if [ -x "/usr/libexec/java_home" ]; then
+      JAVA_HOME="$(/usr/libexec/java_home)"
+      export JAVA_HOME
+    else
+      JAVA_HOME="/Library/Java/Home"
+      export JAVA_HOME
+    fi
+  fi
+  ;;
+esac
+
+if [ -z "$JAVA_HOME" ]; then
+  if [ -r /etc/gentoo-release ]; then
+    JAVA_HOME=$(java-config --jre-home)
+  fi
+fi
+
+# For Cygwin, ensure paths are in UNIX format before anything is touched
+if $cygwin; then
+  [ -n "$JAVA_HOME" ] \
+    && JAVA_HOME=$(cygpath --unix "$JAVA_HOME")
+  [ -n "$CLASSPATH" ] \
+    && CLASSPATH=$(cygpath --path --unix "$CLASSPATH")
+fi
+
+# For Mingw, ensure paths are in UNIX format before anything is touched
+if $mingw; then
+  [ -n "$JAVA_HOME" ] && [ -d "$JAVA_HOME" ] \
+    && JAVA_HOME="$(
+      cd "$JAVA_HOME" || (
+        echo "cannot cd into $JAVA_HOME." >&2
+        exit 1
+      )
+      pwd
+    )"
+fi
+
+if [ -z "$JAVA_HOME" ]; then
+  javaExecutable="$(which javac)"
+  if [ -n "$javaExecutable" ] && ! [ "$(expr "$javaExecutable" : '\([^ ]*\)')" = "no" ]; then
+    # readlink(1) is not available as standard on Solaris 10.
+    readLink=$(which readlink)
+    if [ ! "$(expr "$readLink" : '\([^ ]*\)')" = "no" ]; then
+      if $darwin; then
+        javaHome="$(dirname "$javaExecutable")"
+        javaExecutable="$(cd "$javaHome" && pwd -P)/javac"
+      else
+        javaExecutable="$(readlink -f "$javaExecutable")"
+      fi
+      javaHome="$(dirname "$javaExecutable")"
+      javaHome=$(expr "$javaHome" : '\(.*\)/bin')
+      JAVA_HOME="$javaHome"
+      export JAVA_HOME
+    fi
+  fi
+fi
+
+if [ -z "$JAVACMD" ]; then
+  if [ -n "$JAVA_HOME" ]; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ]; then
+      # IBM's JDK on AIX uses strange locations for the executables
+      JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+      JAVACMD="$JAVA_HOME/bin/java"
+    fi
+  else
+    JAVACMD="$(
+      \unset -f command 2>/dev/null
+      \command -v java
+    )"
+  fi
+fi
+
+if [ ! -x "$JAVACMD" ]; then
+  echo "Error: JAVA_HOME is not defined correctly." >&2
+  echo "  We cannot execute $JAVACMD" >&2
+  exit 1
+fi
+
+if [ -z "$JAVA_HOME" ]; then
+  echo "Warning: JAVA_HOME environment variable is not set." >&2
+fi
+
+# traverses directory structure from process work directory to filesystem root
+# first directory with .mvn subdirectory is considered project base directory
+find_maven_basedir() {
+  if [ -z "$1" ]; then
+    echo "Path not specified to find_maven_basedir" >&2
+    return 1
+  fi
+
+  basedir="$1"
+  wdir="$1"
+  while [ "$wdir" != '/' ]; do
+    if [ -d "$wdir"/.mvn ]; then
+      basedir=$wdir
+      break
+    fi
+    # workaround for JBEAP-8937 (on Solaris 10/Sparc)
+    if [ -d "${wdir}" ]; then
+      wdir=$(
+        cd "$wdir/.." || exit 1
+        pwd
+      )
+    fi
+    # end of workaround
+  done
+  printf '%s' "$(
+    cd "$basedir" || exit 1
+    pwd
+  )"
+}
+
+# concatenates all lines of a file
+concat_lines() {
+  if [ -f "$1" ]; then
+    # Remove \r in case we run on Windows within Git Bash
+    # and check out the repository with auto CRLF management
+    # enabled. Otherwise, we may read lines that are delimited with
+    # \r\n and produce $'-Xarg\r' rather than -Xarg due to word
+    # splitting rules.
+    tr -s '\r\n' ' ' <"$1"
+  fi
+}
+
+log() {
+  if [ "$MVNW_VERBOSE" = true ]; then
+    printf '%s\n' "$1"
+  fi
+}
+
+BASE_DIR=$(find_maven_basedir "$(dirname "$0")")
+if [ -z "$BASE_DIR" ]; then
+  exit 1
+fi
+
+MAVEN_PROJECTBASEDIR=${MAVEN_BASEDIR:-"$BASE_DIR"}
+export MAVEN_PROJECTBASEDIR
+log "$MAVEN_PROJECTBASEDIR"
+
+##########################################################################################
+# Extension to allow automatically downloading the maven-wrapper.jar from Maven-central
+# This allows using the maven wrapper in projects that prohibit checking in binary data.
+##########################################################################################
+wrapperJarPath="$MAVEN_PROJECTBASEDIR/.mvn/wrapper/maven-wrapper.jar"
+if [ -r "$wrapperJarPath" ]; then
+  log "Found $wrapperJarPath"
+else
+  log "Couldn't find $wrapperJarPath, downloading it ..."
+
+  if [ -n "$MVNW_REPOURL" ]; then
+    wrapperUrl="$MVNW_REPOURL/org/apache/maven/wrapper/maven-wrapper/@@project.version@@/maven-wrapper-@@project.version@@.jar"
+  else
+    wrapperUrl="https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/@@project.version@@/maven-wrapper-@@project.version@@.jar"
+  fi
+  while IFS="=" read -r key value; do
+    # Remove '\r' from value to allow usage on windows as IFS does not consider '\r' as a separator ( considers space, tab, new line ('\n'), and custom '=' )
+    safeValue=$(echo "$value" | tr -d '\r')
+    case "$key" in wrapperUrl)
+      wrapperUrl="$safeValue"
+      break
+      ;;
+    esac
+  done <"$MAVEN_PROJECTBASEDIR/.mvn/wrapper/maven-wrapper.properties"
+  log "Downloading from: $wrapperUrl"
+
+  if $cygwin; then
+    wrapperJarPath=$(cygpath --path --windows "$wrapperJarPath")
+  fi
+
+  if command -v wget >/dev/null; then
+    log "Found wget ... using wget"
+    [ "$MVNW_VERBOSE" = true ] && QUIET="" || QUIET="--quiet"
+    if [ -z "$MVNW_USERNAME" ] || [ -z "$MVNW_PASSWORD" ]; then
+      wget $QUIET "$wrapperUrl" -O "$wrapperJarPath" || rm -f "$wrapperJarPath"
+    else
+      wget $QUIET --http-user="$MVNW_USERNAME" --http-password="$MVNW_PASSWORD" "$wrapperUrl" -O "$wrapperJarPath" || rm -f "$wrapperJarPath"
+    fi
+  elif command -v curl >/dev/null; then
+    log "Found curl ... using curl"
+    [ "$MVNW_VERBOSE" = true ] && QUIET="" || QUIET="--silent"
+    if [ -z "$MVNW_USERNAME" ] || [ -z "$MVNW_PASSWORD" ]; then
+      curl $QUIET -o "$wrapperJarPath" "$wrapperUrl" -f -L || rm -f "$wrapperJarPath"
+    else
+      curl $QUIET --user "$MVNW_USERNAME:$MVNW_PASSWORD" -o "$wrapperJarPath" "$wrapperUrl" -f -L || rm -f "$wrapperJarPath"
+    fi
+  else
+    log "Falling back to using Java to download"
+    javaSource="$MAVEN_PROJECTBASEDIR/.mvn/wrapper/MavenWrapperDownloader.java"
+    javaClass="$MAVEN_PROJECTBASEDIR/.mvn/wrapper/MavenWrapperDownloader.class"
+    # For Cygwin, switch paths to Windows format before running javac
+    if $cygwin; then
+      javaSource=$(cygpath --path --windows "$javaSource")
+      javaClass=$(cygpath --path --windows "$javaClass")
+    fi
+    if [ -e "$javaSource" ]; then
+      if [ ! -e "$javaClass" ]; then
+        log " - Compiling MavenWrapperDownloader.java ..."
+        ("$JAVA_HOME/bin/javac" "$javaSource")
+      fi
+      if [ -e "$javaClass" ]; then
+        log " - Running MavenWrapperDownloader.java ..."
+        ("$JAVA_HOME/bin/java" -cp .mvn/wrapper MavenWrapperDownloader "$wrapperUrl" "$wrapperJarPath") || rm -f "$wrapperJarPath"
+      fi
+    fi
+  fi
+fi
+##########################################################################################
+# End of extension
+##########################################################################################
+
+# If specified, validate the SHA-256 sum of the Maven wrapper jar file
+wrapperSha256Sum=""
+while IFS="=" read -r key value; do
+  case "$key" in wrapperSha256Sum)
+    wrapperSha256Sum=$value
+    break
+    ;;
+  esac
+done <"$MAVEN_PROJECTBASEDIR/.mvn/wrapper/maven-wrapper.properties"
+if [ -n "$wrapperSha256Sum" ]; then
+  wrapperSha256Result=false
+  if command -v sha256sum >/dev/null; then
+    if echo "$wrapperSha256Sum  $wrapperJarPath" | sha256sum -c >/dev/null 2>&1; then
+      wrapperSha256Result=true
+    fi
+  elif command -v shasum >/dev/null; then
+    if echo "$wrapperSha256Sum  $wrapperJarPath" | shasum -a 256 -c >/dev/null 2>&1; then
+      wrapperSha256Result=true
+    fi
+  else
+    echo "Checksum validation was requested but neither 'sha256sum' or 'shasum' are available." >&2
+    echo "Please install either command, or disable validation by removing 'wrapperSha256Sum' from your maven-wrapper.properties." >&2
+    exit 1
+  fi
+  if [ $wrapperSha256Result = false ]; then
+    echo "Error: Failed to validate Maven wrapper SHA-256, your Maven wrapper might be compromised." >&2
+    echo "Investigate or delete $wrapperJarPath to attempt a clean download." >&2
+    echo "If you updated your Maven version, you need to update the specified wrapperSha256Sum property." >&2
+    exit 1
+  fi
+fi
+
+MAVEN_OPTS="$(concat_lines "$MAVEN_PROJECTBASEDIR/.mvn/jvm.config") $MAVEN_OPTS"
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin; then
+  [ -n "$JAVA_HOME" ] \
+    && JAVA_HOME=$(cygpath --path --windows "$JAVA_HOME")
+  [ -n "$CLASSPATH" ] \
+    && CLASSPATH=$(cygpath --path --windows "$CLASSPATH")
+  [ -n "$MAVEN_PROJECTBASEDIR" ] \
+    && MAVEN_PROJECTBASEDIR=$(cygpath --path --windows "$MAVEN_PROJECTBASEDIR")
+fi
+
+# Provide a "standardized" way to retrieve the CLI args that will
+# work with both Windows and non-Windows executions.
+MAVEN_CMD_LINE_ARGS="$MAVEN_CONFIG $*"
+export MAVEN_CMD_LINE_ARGS
+
+WRAPPER_LAUNCHER=org.apache.maven.wrapper.MavenWrapperMain
+
+# shellcheck disable=SC2086 # safe args
+exec "$JAVACMD" \
+  $MAVEN_OPTS \
+  $MAVEN_DEBUG_OPTS \
+  -classpath "$MAVEN_PROJECTBASEDIR/.mvn/wrapper/maven-wrapper.jar" \
+  "-Dmaven.multiModuleProjectDirectory=${MAVEN_PROJECTBASEDIR}" \
+  ${WRAPPER_LAUNCHER} $MAVEN_CONFIG "$@"

mvnw.cmd

@@ -0,0 +1,206 @@
+@REM ----------------------------------------------------------------------------
+@REM Licensed to the Apache Software Foundation (ASF) under one
+@REM or more contributor license agreements.  See the NOTICE file
+@REM distributed with this work for additional information
+@REM regarding copyright ownership.  The ASF licenses this file
+@REM to you under the Apache License, Version 2.0 (the
+@REM "License"); you may not use this file except in compliance
+@REM with the License.  You may obtain a copy of the License at
+@REM
+@REM    http://www.apache.org/licenses/LICENSE-2.0
+@REM
+@REM Unless required by applicable law or agreed to in writing,
+@REM software distributed under the License is distributed on an
+@REM "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+@REM KIND, either express or implied.  See the License for the
+@REM specific language governing permissions and limitations
+@REM under the License.
+@REM ----------------------------------------------------------------------------
+
+@REM ----------------------------------------------------------------------------
+@REM Apache Maven Wrapper startup batch script, version @@project.version@@
+@REM
+@REM Required ENV vars:
+@REM JAVA_HOME - location of a JDK home dir
+@REM
+@REM Optional ENV vars
+@REM MAVEN_BATCH_ECHO - set to 'on' to enable the echoing of the batch commands
+@REM MAVEN_BATCH_PAUSE - set to 'on' to wait for a keystroke before ending
+@REM MAVEN_OPTS - parameters passed to the Java VM when running Maven
+@REM     e.g. to debug Maven itself, use
+@REM set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000
+@REM MAVEN_SKIP_RC - flag to disable loading of mavenrc files
+@REM ----------------------------------------------------------------------------
+
+@REM Begin all REM lines with '@' in case MAVEN_BATCH_ECHO is 'on'
+@echo off
+@REM set title of command window
+title %0
+@REM enable echoing by setting MAVEN_BATCH_ECHO to 'on'
+@if "%MAVEN_BATCH_ECHO%" == "on"  echo %MAVEN_BATCH_ECHO%
+
+@REM set %HOME% to equivalent of $HOME
+if "%HOME%" == "" (set "HOME=%HOMEDRIVE%%HOMEPATH%")
+
+@REM Execute a user defined script before this one
+if not "%MAVEN_SKIP_RC%" == "" goto skipRcPre
+@REM check for pre script, once with legacy .bat ending and once with .cmd ending
+if exist "%USERPROFILE%\mavenrc_pre.bat" call "%USERPROFILE%\mavenrc_pre.bat" %*
+if exist "%USERPROFILE%\mavenrc_pre.cmd" call "%USERPROFILE%\mavenrc_pre.cmd" %*
+:skipRcPre
+
+@setlocal
+
+set ERROR_CODE=0
+
+@REM To isolate internal variables from possible post scripts, we use another setlocal
+@setlocal
+
+@REM ==== START VALIDATION ====
+if not "%JAVA_HOME%" == "" goto OkJHome
+
+echo. >&2
+echo Error: JAVA_HOME not found in your environment. >&2
+echo Please set the JAVA_HOME variable in your environment to match the >&2
+echo location of your Java installation. >&2
+echo. >&2
+goto error
+
+:OkJHome
+if exist "%JAVA_HOME%\bin\java.exe" goto init
+
+echo. >&2
+echo Error: JAVA_HOME is set to an invalid directory. >&2
+echo JAVA_HOME = "%JAVA_HOME%" >&2
+echo Please set the JAVA_HOME variable in your environment to match the >&2
+echo location of your Java installation. >&2
+echo. >&2
+goto error
+
+@REM ==== END VALIDATION ====
+
+:init
+
+@REM Find the project base dir, i.e. the directory that contains the folder ".mvn".
+@REM Fallback to current working directory if not found.
+
+set MAVEN_PROJECTBASEDIR=%MAVEN_BASEDIR%
+IF NOT "%MAVEN_PROJECTBASEDIR%"=="" goto endDetectBaseDir
+
+set EXEC_DIR=%CD%
+set WDIR=%EXEC_DIR%
+:findBaseDir
+IF EXIST "%WDIR%"\.mvn goto baseDirFound
+cd ..
+IF "%WDIR%"=="%CD%" goto baseDirNotFound
+set WDIR=%CD%
+goto findBaseDir
+
+:baseDirFound
+set MAVEN_PROJECTBASEDIR=%WDIR%
+cd "%EXEC_DIR%"
+goto endDetectBaseDir
+
+:baseDirNotFound
+set MAVEN_PROJECTBASEDIR=%EXEC_DIR%
+cd "%EXEC_DIR%"
+
+:endDetectBaseDir
+
+IF NOT EXIST "%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config" goto endReadAdditionalConfig
+
+@setlocal EnableExtensions EnableDelayedExpansion
+for /F "usebackq delims=" %%a in ("%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config") do set JVM_CONFIG_MAVEN_PROPS=!JVM_CONFIG_MAVEN_PROPS! %%a
+@endlocal & set JVM_CONFIG_MAVEN_PROPS=%JVM_CONFIG_MAVEN_PROPS%
+
+:endReadAdditionalConfig
+
+SET MAVEN_JAVA_EXE="%JAVA_HOME%\bin\java.exe"
+set WRAPPER_JAR="%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.jar"
+set WRAPPER_LAUNCHER=org.apache.maven.wrapper.MavenWrapperMain
+
+set WRAPPER_URL="https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/@@project.version@@/maven-wrapper-@@project.version@@.jar"
+
+FOR /F "usebackq tokens=1,2 delims==" %%A IN ("%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.properties") DO (
+    IF "%%A"=="wrapperUrl" SET WRAPPER_URL=%%B
+)
+
+@REM Extension to allow automatically downloading the maven-wrapper.jar from Maven-central
+@REM This allows using the maven wrapper in projects that prohibit checking in binary data.
+if exist %WRAPPER_JAR% (
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Found %WRAPPER_JAR%
+    )
+) else (
+    if not "%MVNW_REPOURL%" == "" (
+        SET WRAPPER_URL="%MVNW_REPOURL%/org/apache/maven/wrapper/maven-wrapper/@@project.version@@/maven-wrapper-@@project.version@@.jar"
+    )
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Couldn't find %WRAPPER_JAR%, downloading it ...
+        echo Downloading from: %WRAPPER_URL%
+    )
+
+    powershell -Command "&{"^
+		"$webclient = new-object System.Net.WebClient;"^
+		"if (-not ([string]::IsNullOrEmpty('%MVNW_USERNAME%') -and [string]::IsNullOrEmpty('%MVNW_PASSWORD%'))) {"^
+		"$webclient.Credentials = new-object System.Net.NetworkCredential('%MVNW_USERNAME%', '%MVNW_PASSWORD%');"^
+		"}"^
+		"[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12; $webclient.DownloadFile('%WRAPPER_URL%', '%WRAPPER_JAR%')"^
+		"}"
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Finished downloading %WRAPPER_JAR%
+    )
+)
+@REM End of extension
+
+@REM If specified, validate the SHA-256 sum of the Maven wrapper jar file
+SET WRAPPER_SHA_256_SUM=""
+FOR /F "usebackq tokens=1,2 delims==" %%A IN ("%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.properties") DO (
+    IF "%%A"=="wrapperSha256Sum" SET WRAPPER_SHA_256_SUM=%%B
+)
+IF NOT %WRAPPER_SHA_256_SUM%=="" (
+    powershell -Command "&{"^
+       "Import-Module $PSHOME\Modules\Microsoft.PowerShell.Utility -Function Get-FileHash;"^
+       "$hash = (Get-FileHash \"%WRAPPER_JAR%\" -Algorithm SHA256).Hash.ToLower();"^
+       "If('%WRAPPER_SHA_256_SUM%' -ne $hash){"^
+       "  Write-Error 'Error: Failed to validate Maven wrapper SHA-256, your Maven wrapper might be compromised.';"^
+       "  Write-Error 'Investigate or delete %WRAPPER_JAR% to attempt a clean download.';"^
+       "  Write-Error 'If you updated your Maven version, you need to update the specified wrapperSha256Sum property.';"^
+       "  exit 1;"^
+       "}"^
+       "}"
+    if ERRORLEVEL 1 goto error
+)
+
+@REM Provide a "standardized" way to retrieve the CLI args that will
+@REM work with both Windows and non-Windows executions.
+set MAVEN_CMD_LINE_ARGS=%*
+
+%MAVEN_JAVA_EXE% ^
+  %JVM_CONFIG_MAVEN_PROPS% ^
+  %MAVEN_OPTS% ^
+  %MAVEN_DEBUG_OPTS% ^
+  -classpath %WRAPPER_JAR% ^
+  "-Dmaven.multiModuleProjectDirectory=%MAVEN_PROJECTBASEDIR%" ^
+  %WRAPPER_LAUNCHER% %MAVEN_CONFIG% %*
+if ERRORLEVEL 1 goto error
+goto end
+
+:error
+set ERROR_CODE=1
+
+:end
+@endlocal & set ERROR_CODE=%ERROR_CODE%
+
+if not "%MAVEN_SKIP_RC%"=="" goto skipRcPost
+@REM check for post script, once with legacy .bat ending and once with .cmd ending
+if exist "%USERPROFILE%\mavenrc_post.bat" call "%USERPROFILE%\mavenrc_post.bat"
+if exist "%USERPROFILE%\mavenrc_post.cmd" call "%USERPROFILE%\mavenrc_post.cmd"
+:skipRcPost
+
+@REM pause the script if MAVEN_BATCH_PAUSE is set to 'on'
+if "%MAVEN_BATCH_PAUSE%"=="on" pause
+
+if "%MAVEN_TERMINATE_CMD%"=="on" exit %ERROR_CODE%
+
+cmd /C exit /B %ERROR_CODE%

pom.xml

@@ -0,0 +1,146 @@
+<?xml version="1.0"?>
+<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"
+  xmlns="http://maven.apache.org/POM/4.0.0"
+  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>com.demo</groupId>
+  <artifactId>otel-quarkus-demo</artifactId>
+  <version>1.0.0</version>
+
+  <properties>
+    <compiler-plugin.version>3.13.0</compiler-plugin.version>
+    <maven.compiler.release>21</maven.compiler.release>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <quarkus.platform.version>3.35.1</quarkus.platform.version>
+    <quarkiverse-micrometer-registry.version>3.5.0</quarkiverse-micrometer-registry.version>
+    <clean-plugin.version>3.4.0</clean-plugin.version>
+    <resources-plugin.version>3.3.1</resources-plugin.version>
+    <jar-plugin.version>3.4.2</jar-plugin.version>
+    <install-plugin.version>3.1.3</install-plugin.version>
+    <deploy-plugin.version>3.1.3</deploy-plugin.version>
+    <surefire-plugin.version>3.5.1</surefire-plugin.version>
+    <failsafe-plugin.version>3.5.1</failsafe-plugin.version>
+    <site-plugin.version>3.21.0</site-plugin.version>
+  </properties>
+
+  <dependencyManagement>
+    <dependencies>
+      <dependency>
+        <groupId>io.quarkus.platform</groupId>
+        <artifactId>quarkus-bom</artifactId>
+        <version>${quarkus.platform.version}</version>
+        <type>pom</type>
+        <scope>import</scope>
+      </dependency>
+    </dependencies>
+  </dependencyManagement>
+
+  <dependencies>
+    <!-- REST -->
+    <dependency>
+      <groupId>io.quarkus</groupId>
+      <artifactId>quarkus-rest</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>io.quarkus</groupId>
+      <artifactId>quarkus-rest-jackson</artifactId>
+    </dependency>
+
+    <!-- OpenTelemetry — traces + metrics + logs via OTLP -->
+    <dependency>
+      <groupId>io.quarkus</groupId>
+      <artifactId>quarkus-opentelemetry</artifactId>
+    </dependency>
+
+    <!-- Micrometer with Prometheus registry (for /q/metrics scrape endpoint) -->
+    <dependency>
+      <groupId>io.quarkus</groupId>
+      <artifactId>quarkus-micrometer-registry-prometheus</artifactId>
+    </dependency>
+
+    <!-- OTLP exporter for micrometer metrics (pushed via OTel) -->
+    <dependency>
+      <groupId>io.quarkiverse.micrometer.registry</groupId>
+      <artifactId>quarkus-micrometer-registry-otlp</artifactId>
+      <version>${quarkiverse-micrometer-registry.version}</version>
+    </dependency>
+
+    <!-- JSON structured console logging -->
+    <dependency>
+      <groupId>io.quarkus</groupId>
+      <artifactId>quarkus-logging-json</artifactId>
+    </dependency>
+
+    <!-- Health checks -->
+    <dependency>
+      <groupId>io.quarkus</groupId>
+      <artifactId>quarkus-smallrye-health</artifactId>
+    </dependency>
+
+    <!-- Container image build -->
+    <dependency>
+      <groupId>io.quarkus</groupId>
+      <artifactId>quarkus-container-image-jib</artifactId>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <pluginManagement>
+      <plugins>
+        <plugin>
+          <artifactId>maven-clean-plugin</artifactId>
+          <version>${clean-plugin.version}</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-resources-plugin</artifactId>
+          <version>${resources-plugin.version}</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-compiler-plugin</artifactId>
+          <version>${compiler-plugin.version}</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-surefire-plugin</artifactId>
+          <version>${surefire-plugin.version}</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-failsafe-plugin</artifactId>
+          <version>${failsafe-plugin.version}</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-jar-plugin</artifactId>
+          <version>${jar-plugin.version}</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-install-plugin</artifactId>
+          <version>${install-plugin.version}</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-deploy-plugin</artifactId>
+          <version>${deploy-plugin.version}</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-site-plugin</artifactId>
+          <version>${site-plugin.version}</version>
+        </plugin>
+      </plugins>
+    </pluginManagement>
+    <plugins>
+      <plugin>
+        <groupId>io.quarkus.platform</groupId>
+        <artifactId>quarkus-maven-plugin</artifactId>
+        <version>${quarkus.platform.version}</version>
+        <extensions>true</extensions>
+        <executions>
+          <execution>
+            <goals>
+              <goal>build</goal>
+              <goal>generate-code</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+</project>

src/main/java/com/demo/InventoryService.java

@@ -0,0 +1,82 @@
+package com.demo;
+
+import io.micrometer.core.instrument.Gauge;
+import io.micrometer.core.instrument.MeterRegistry;
+import jakarta.annotation.PostConstruct;
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.inject.Inject;
+import org.jboss.logging.Logger;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/**
+ * Simulated inventory service that exposes stock levels as Micrometer gauge metrics.
+ * Each product has a gauge "inventory_level" with a tag "product".
+ */
+@ApplicationScoped
+public class InventoryService {
+
+    private static final Logger LOG = Logger.getLogger(InventoryService.class);
+
+    @Inject
+    MeterRegistry registry;
+
+    private final ConcurrentHashMap<String, AtomicInteger> stock = new ConcurrentHashMap<>();
+
+    @PostConstruct
+    void init() {
+        // Seed initial inventory
+        initProduct("laptop", 50);
+        initProduct("keyboard", 200);
+        initProduct("mouse", 300);
+        initProduct("monitor", 75);
+        initProduct("headset", 120);
+        initProduct("webcam", 90);
+
+        LOG.info("Inventory service initialized with 6 products");
+    }
+
+    private void initProduct(String product, int initialStock) {
+        AtomicInteger level = new AtomicInteger(initialStock);
+        stock.put(product, level);
+
+        // Register a gauge that tracks the live value of the AtomicInteger
+        Gauge.builder("inventory_level", level, AtomicInteger::get)
+                .description("Current inventory level")
+                .tag("product", product)
+                .register(registry);
+    }
+
+    public int getStock(String product) {
+        AtomicInteger level = stock.get(product);
+        if (level == null) {
+            // Unknown product — treat as out of stock
+            return 0;
+        }
+        return level.get();
+    }
+
+    public void decrementStock(String product, int quantity) {
+        AtomicInteger level = stock.get(product);
+        if (level != null) {
+            int newLevel = level.addAndGet(-quantity);
+            LOG.debugf("Inventory updated: product=%s, decremented=%d, new_level=%d",
+                    product, quantity, newLevel);
+
+            // Restock if level drops below 10 (simulates auto-replenishment)
+            if (newLevel < 10) {
+                int restock = 100;
+                level.addAndGet(restock);
+                LOG.infof("Auto-restocked product=%s by %d units (was at %d)", product, restock, newLevel);
+            }
+        }
+    }
+
+    public Map<String, Integer> getInventoryLevels() {
+        Map<String, Integer> levels = new ConcurrentHashMap<>();
+        stock.forEach((product, level) -> levels.put(product, level.get()));
+        return levels;
+    }
+}

src/main/java/com/demo/Order.java

@@ -0,0 +1,31 @@
+package com.demo;
+
+import java.time.Instant;
+import java.util.UUID;
+
+public class Order {
+
+    public String id;
+    public String customerId;
+    public String product;
+    public int quantity;
+    public double unitPrice;
+    public double totalPrice;
+    public String status;
+    public Instant createdAt;
+
+    public Order() {
+        this.id = UUID.randomUUID().toString().substring(0, 8);
+        this.createdAt = Instant.now();
+        this.status = "CREATED";
+    }
+
+    public Order(String customerId, String product, int quantity, double unitPrice) {
+        this();
+        this.customerId = customerId;
+        this.product = product;
+        this.quantity = quantity;
+        this.unitPrice = unitPrice;
+        this.totalPrice = quantity * unitPrice;
+    }
+}

src/main/java/com/demo/OrderResource.java

@@ -0,0 +1,295 @@
+package com.demo;
+
+import io.micrometer.core.instrument.Counter;
+import io.micrometer.core.instrument.DistributionSummary;
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.Timer;
+import io.opentelemetry.api.trace.Span;
+import io.opentelemetry.api.trace.SpanKind;
+import io.opentelemetry.api.trace.StatusCode;
+import io.opentelemetry.api.trace.Tracer;
+import io.opentelemetry.context.Scope;
+import jakarta.inject.Inject;
+import jakarta.ws.rs.*;
+import jakarta.ws.rs.core.MediaType;
+import jakarta.ws.rs.core.Response;
+import org.jboss.logging.Logger;
+
+import java.time.Duration;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.ThreadLocalRandom;
+
+@Path("/api")
+@Produces(MediaType.APPLICATION_JSON)
+public class OrderResource {
+
+    private static final Logger LOG = Logger.getLogger(OrderResource.class);
+
+    @Inject
+    Tracer tracer;
+
+    @Inject
+    MeterRegistry registry;
+
+    @Inject
+    InventoryService inventoryService;
+
+    // In-memory store for demo purposes
+    private final List<Order> orders = new CopyOnWriteArrayList<>();
+
+    // ────── Custom Metrics (registered lazily) ──────
+
+    private Counter ordersCounter(String status) {
+        return Counter.builder("orders")
+                .description("Total number of orders processed")
+                .tag("status", status)
+                .register(registry);
+    }
+
+    private Counter revenueCounter() {
+        return Counter.builder("orders_amount")
+                .description("Total order revenue")
+                .baseUnit("dollars")
+                .register(registry);
+    }
+
+    private Timer orderProcessingTimer() {
+        return Timer.builder("order_processing_duration")
+                .description("Time spent processing an order")
+                .publishPercentiles(0.5, 0.9, 0.95, 0.99)
+                .register(registry);
+    }
+
+    private DistributionSummary orderSizeSummary() {
+        return DistributionSummary.builder("order_item_count")
+                .description("Number of items per order")
+                .publishPercentiles(0.5, 0.9)
+                .register(registry);
+    }
+
+    // ────── Endpoints ──────
+
+    @GET
+    @Path("/health")
+    public Response health() {
+        return Response.ok(Map.of("status", "UP", "service", "otel-quarkus-demo")).build();
+    }
+
+    /**
+     * POST /api/orders — Create and process an order.
+     * Demonstrates: custom spans, span attributes, custom metrics, error injection, latency simulation.
+     */
+    @POST
+    @Path("/orders")
+    @Consumes(MediaType.APPLICATION_JSON)
+    public Response createOrder(OrderRequest request) {
+        LOG.infof("Received order request: product=%s, quantity=%d, customerId=%s",
+                request.product, request.quantity, request.customerId);
+
+        // Start a custom parent span for the full order processing
+        Span orderSpan = tracer.spanBuilder("processOrder")
+                .setSpanKind(SpanKind.INTERNAL)
+                .setAttribute("order.product", request.product)
+                .setAttribute("order.quantity", (long) request.quantity)
+                .setAttribute("order.customer_id", request.customerId)
+                .startSpan();
+
+        try (Scope scope = orderSpan.makeCurrent()) {
+            return orderProcessingTimer().record(() -> {
+                try {
+                    // Step 1: Validate the order
+                    validateOrder(request);
+
+                    // Step 2: Check inventory
+                    boolean inStock = checkInventory(request.product, request.quantity);
+                    if (!inStock) {
+                        orderSpan.setStatus(StatusCode.ERROR, "Insufficient inventory");
+                        ordersCounter("rejected_no_stock").increment();
+                        LOG.warnf("Order rejected — insufficient inventory for product=%s, requested=%d",
+                                request.product, request.quantity);
+                        return Response.status(Response.Status.CONFLICT)
+                                .entity(Map.of("error", "Insufficient inventory", "product", request.product))
+                                .build();
+                    }
+
+                    // Step 3: Process payment (simulated)
+                    processPayment(request);
+
+                    // Step 4: Create the order
+                    Order order = new Order(request.customerId, request.product,
+                            request.quantity, request.unitPrice);
+
+                    // Simulate processing time based on complexity
+                    String processingType = request.quantity > 5 ? "complex" : "simple";
+                    orderSpan.setAttribute("order.processing_type", processingType);
+                    orderSpan.setAttribute("order.total_price", order.totalPrice);
+
+                    simulateProcessingDelay(processingType);
+
+                    // Randomly inject errors (~10% of the time) for troubleshooting demo
+                    if (ThreadLocalRandom.current().nextDouble() < 0.10) {
+                        throw new RuntimeException("Downstream fulfillment service timeout");
+                    }
+
+                    order.status = "COMPLETED";
+                    orders.add(order);
+
+                    // Record metrics
+                    ordersCounter("completed").increment();
+                    revenueCounter().increment(order.totalPrice);
+                    orderSizeSummary().record(request.quantity);
+
+                    // Update inventory
+                    inventoryService.decrementStock(request.product, request.quantity);
+
+                    LOG.infof("Order %s completed: product=%s, quantity=%d, total=%.2f, type=%s",
+                            order.id, order.product, order.quantity, order.totalPrice, processingType);
+
+                    orderSpan.setAttribute("order.id", order.id);
+                    orderSpan.setStatus(StatusCode.OK);
+
+                    return Response.status(Response.Status.CREATED).entity(order).build();
+
+                } catch (IllegalArgumentException e) {
+                    orderSpan.setStatus(StatusCode.ERROR, e.getMessage());
+                    orderSpan.recordException(e);
+                    ordersCounter("rejected_validation").increment();
+                    LOG.errorf("Order validation failed: %s", e.getMessage());
+                    return Response.status(Response.Status.BAD_REQUEST)
+                            .entity(Map.of("error", e.getMessage())).build();
+
+                } catch (RuntimeException e) {
+                    orderSpan.setStatus(StatusCode.ERROR, e.getMessage());
+                    orderSpan.recordException(e);
+                    ordersCounter("failed").increment();
+                    LOG.errorf(e, "Order processing failed: %s", e.getMessage());
+                    return Response.status(Response.Status.INTERNAL_SERVER_ERROR)
+                            .entity(Map.of("error", "Order processing failed", "detail", e.getMessage())).build();
+                }
+            });
+        } finally {
+            orderSpan.end();
+        }
+    }
+
+    /**
+     * GET /api/orders — List all orders.
+     */
+    @GET
+    @Path("/orders")
+    public Response listOrders() {
+        LOG.debugf("Listing %d orders", orders.size());
+        return Response.ok(orders).build();
+    }
+
+    /**
+     * GET /api/orders/{id} — Get a single order by ID.
+     */
+    @GET
+    @Path("/orders/{id}")
+    public Response getOrder(@PathParam("id") String id) {
+        return orders.stream()
+                .filter(o -> o.id.equals(id))
+                .findFirst()
+                .map(o -> Response.ok(o).build())
+                .orElseGet(() -> {
+                    LOG.warnf("Order not found: %s", id);
+                    return Response.status(Response.Status.NOT_FOUND)
+                            .entity(Map.of("error", "Order not found")).build();
+                });
+    }
+
+    /**
+     * GET /api/inventory — Current inventory levels (gauge metrics).
+     */
+    @GET
+    @Path("/inventory")
+    public Response getInventory() {
+        return Response.ok(inventoryService.getInventoryLevels()).build();
+    }
+
+    // ────── Internal Processing Steps (each with its own span) ──────
+
+    private void validateOrder(OrderRequest request) {
+        Span span = tracer.spanBuilder("validateOrder").startSpan();
+        try (Scope s = span.makeCurrent()) {
+            if (request.product == null || request.product.isBlank()) {
+                throw new IllegalArgumentException("Product name is required");
+            }
+            if (request.quantity <= 0) {
+                throw new IllegalArgumentException("Quantity must be positive");
+            }
+            if (request.unitPrice <= 0) {
+                throw new IllegalArgumentException("Unit price must be positive");
+            }
+            span.setAttribute("validation.passed", true);
+            LOG.debugf("Order validation passed for product=%s", request.product);
+        } finally {
+            span.end();
+        }
+    }
+
+    private boolean checkInventory(String product, int quantity) {
+        Span span = tracer.spanBuilder("checkInventory")
+                .setAttribute("inventory.product", product)
+                .setAttribute("inventory.requested_quantity", (long) quantity)
+                .startSpan();
+        try (Scope s = span.makeCurrent()) {
+            // Simulate a small network call delay
+            Thread.sleep(ThreadLocalRandom.current().nextInt(10, 50));
+            int available = inventoryService.getStock(product);
+            span.setAttribute("inventory.available", (long) available);
+            boolean inStock = available >= quantity;
+            span.setAttribute("inventory.in_stock", inStock);
+            LOG.debugf("Inventory check: product=%s, available=%d, requested=%d, inStock=%s",
+                    product, available, quantity, inStock);
+            return inStock;
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+            return false;
+        } finally {
+            span.end();
+        }
+    }
+
+    private void processPayment(OrderRequest request) {
+        Span span = tracer.spanBuilder("processPayment")
+                .setSpanKind(SpanKind.CLIENT)
+                .setAttribute("payment.amount", request.quantity * request.unitPrice)
+                .setAttribute("payment.currency", "USD")
+                .startSpan();
+        try (Scope s = span.makeCurrent()) {
+            // Simulate payment gateway latency
+            Thread.sleep(ThreadLocalRandom.current().nextInt(20, 150));
+            span.setAttribute("payment.status", "approved");
+            LOG.infof("Payment processed: amount=%.2f", request.quantity * request.unitPrice);
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+        } finally {
+            span.end();
+        }
+    }
+
+    private void simulateProcessingDelay(String type) {
+        try {
+            if ("complex".equals(type)) {
+                Thread.sleep(ThreadLocalRandom.current().nextInt(200, 800));
+            } else {
+                Thread.sleep(ThreadLocalRandom.current().nextInt(10, 100));
+            }
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+        }
+    }
+
+    // ────── Request DTO ──────
+
+    public static class OrderRequest {
+        public String customerId;
+        public String product;
+        public int quantity;
+        public double unitPrice;
+    }
+}

src/main/resources/application.properties

@@ -0,0 +1,44 @@
+# ── Application ──────────────────────────────────────────────
+quarkus.application.name=otel-quarkus-demo
+quarkus.application.version=1.0.0
+quarkus.http.port=8080
+
+# ── OpenTelemetry ────────────────────────────────────────────
+# OTLP endpoint — points to the OTel Collector service in-cluster
+quarkus.otel.exporter.otlp.endpoint=http://otel-collector-opentelemetry-collector.argos:4317
+
+# Resource attributes
+quarkus.otel.resource.attributes=service.name=otel-quarkus-demo,service.namespace=argos,deployment.environment=dev
+
+# Enable all signals
+quarkus.otel.traces.enabled=true
+quarkus.otel.metrics.enabled=true
+quarkus.otel.logs.enabled=true
+
+# Sampler — collect everything for the demo (use ratio in prod)
+quarkus.otel.traces.sampler=always_on
+
+# ── Micrometer ───────────────────────────────────────────────
+# Prometheus scrape endpoint at /q/metrics (belt-and-suspenders with OTLP push)
+quarkus.micrometer.export.prometheus.enabled=true
+quarkus.micrometer.export.prometheus.path=/q/metrics
+
+# OTLP push for micrometer metrics (goes to OTel Collector)
+quarkus.micrometer.export.otlp.url=http://otel-collector-opentelemetry-collector.argos:4318/v1/metrics
+
+# ── Logging ──────────────────────────────────────────────────
+# JSON structured logging — makes logs parseable in Loki
+quarkus.log.console.format=%d{yyyy-MM-dd HH:mm:ss.SSS} %-5p traceId=%X{traceId} spanId=%X{spanId} [%c{2.}] (%t) %s%e%n
+quarkus.log.console.json.enabled=false
+
+# Log level
+quarkus.log.level=INFO
+quarkus.log.category."com.demo".level=DEBUG
+
+# ── Health ───────────────────────────────────────────────────
+quarkus.smallrye-health.root-path=/q/health
+
+# ── Container Image ─────────────────────────────────────────
+quarkus.container-image.group=global
+quarkus.container-image.name=quarkus-app
+quarkus.container-image.tag=latest