Create Dockerfile

Added Dockerfile for eased render.com deployment and future DT trial

Signed-off-by: lii5a <liisa.tallinn@gmail.com>

Dockerfile

@@ -0,0 +1,64 @@
+# ---------- 1) BUILD STAGE: Build the Spring PetClinic app with Maven ----------
+FROM eclipse-temurin:17-jdk as build
+
+# Install Maven Wrapper dependencies if needed
+WORKDIR /app
+
+# Copy only build-related files first to leverage Docker layer caching
+COPY mvnw ./
+COPY .mvn .mvn
+COPY pom.xml ./
+
+# Pre-fetch dependencies (faster builds)
+RUN chmod +x mvnw && ./mvnw -B -q -DskipTests dependency:go-offline
+
+# Now copy the sources and build the JAR
+COPY src ./src
+RUN ./mvnw -B -DskipTests package
+
+# Find the built jar (petclinic usually builds to target/*.jar)
+# We'll move it to a predictable location.
+RUN mkdir -p /out && cp target/*.jar /out/app.jar
+
+
+# ---------- 2) RUNTIME STAGE: Run the app with OpenTelemetry agent ----------
+FROM eclipse-temurin:17-jre as runtime
+
+WORKDIR /app
+
+# ---- OpenTelemetry Java Agent version (editable) ----
+ARG OTEL_JAVA_AGENT_VERSION=1.33.4
+ENV OTEL_AGENT_DIR=/otel
+RUN mkdir -p ${OTEL_AGENT_DIR}
+
+# Download the OpenTelemetry Java agent
+# You can change the version above if needed.
+ADD https://github.com/open-telemetry/opentelemetry-java-instrumentation/releases/download/v${OTEL_JAVA_AGENT_VERSION}/opentelemetry-javaagent.jar ${OTEL_AGENT_DIR}/otel-agent.jar
+
+# Copy app jar from the build stage
+COPY --from=build /out/app.jar /app/app.jar
+
+# ---- Default OpenTelemetry env vars (override in Render) ----
+# Service name as it will appear in Dynatrace
+ENV OTEL_SERVICE_NAME=petclinic
+# Set resource attributes (useful for filtering/grouping in Dynatrace)
+ENV OTEL_RESOURCE_ATTRIBUTES=service.namespace=demo,service.version=1.0.0,deployment.environment=render
+# Export traces (and optionally metrics/logs) to Dynatrace OTLP endpoint
+# You WILL override the endpoint and headers in Render dashboard.
+ENV OTEL_TRACES_EXPORTER=otlp
+ENV OTEL_METRICS_EXPORTER=none
+ENV OTEL_LOGS_EXPORTER=none
+
+# JVM options: attach the OTel Java agent
+ENV JAVA_TOOL_OPTIONS="-javaagent:/otel/otel-agent.jar"
+
+# Expose PetClinic default port (usually 8080)
+EXPOSE 8080
+
+# Health check (optional, adjust if your app exposes actuator/health)
+# HEALTHCHECK --interval=30s --timeout=5s --start-period=60s --retries=5 \
+#   CMD curl -fsS http://localhost:8080/ || exit 1
+
+# Start the app
+ENTRYPOINT ["java", "-jar", "app.jar"]
+``