Add Dockerfile

Dockerfile

@@ -0,0 +1,22 @@
+FROM azul/zulu-openjdk:21-jdk-crac-latest as builder
+WORKDIR application
+
+ADD ./.mvn .mvn/
+ADD ./mvnw mvnw
+ADD ./pom.xml pom.xml
+ADD ./src src/
+ADD ./.git .git/
+RUN ./mvnw -V clean package -DskipTests --no-transfer-progress && \
+    cp target/*.jar application.jar && \
+    java -Djarmode=layertools -jar application.jar extract
+
+FROM azul/zulu-openjdk:21-jdk-crac-latest
+WORKDIR application
+
+COPY --from=builder application/dependencies/ ./
+COPY --from=builder application/spring-boot-loader/ ./
+COPY --from=builder application/snapshot-dependencies/ ./
+COPY --from=builder application/application/ ./
+COPY entrypoint.sh ./
+
+ENTRYPOINT ["/application/entrypoint.sh"]

README.md

@@ -38,3 +38,68 @@ jcmd target/example-spring-boot-0.0.1-SNAPSHOT.jar JDK.checkpoint
 ```
 $JAVA_HOME/bin/java -XX:CRaCRestoreFrom=cr
 ```
+
+## Docker image
+
+### Building
+
+Create a Docker image using the provided [`Dockerfile`](./Dockerfile) with the following command:
+
+```
+docker build -t example-spring-boot .
+```
+
+### Running
+
+Run the built Docker image with the following command:
+
+```
+docker run -p 8080:8080 \
+  --cap-add CHECKPOINT_RESTORE \
+  --cap-add NET_ADMIN \
+  --cap-add SYS_PTRACE \
+  --cap-add SYS_ADMIN \
+  -v /tmp/crac:/var/crac \
+  -e CHECKPOINT_RESTORE_FILES_DIR=/var/crac \
+  --rm \
+  example-spring-boot
+```
+
+The following logs will be outputted. A Checkpoint is created 10 seconds after the application starts. This time can be changed with the `SLEEP_BEFORE_CHECKPOINT` environment variable in [`entrypoint.sh`](./entrypoint.sh).
+
+```
+  .   ____          _            __ _ _
+ /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
+( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
+ \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
+  '  |____| .__|_| |_|_| |_\__, | / / / /
+ =========|_|==============|___/=/_/_/_/
+ :: Spring Boot ::                (v3.2.0)
+
+2023-11-27T07:51:47.375Z  INFO 8 --- [           main] com.example.springboot.Application       : Starting Application v0.0.1-SNAPSHOT using Java 21.0.1 with PID 8 (/application/BOOT-INF/classes started by root in /application)
+2023-11-27T07:51:47.378Z  INFO 8 --- [           main] com.example.springboot.Application       : No active profile set, falling back to 1 default profile: "default"
+2023-11-27T07:51:48.138Z  INFO 8 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port 8080 (http)
+2023-11-27T07:51:48.146Z  INFO 8 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
+2023-11-27T07:51:48.146Z  INFO 8 --- [           main] o.apache.catalina.core.StandardEngine    : Starting Servlet engine: [Apache Tomcat/10.1.16]
+2023-11-27T07:51:48.176Z  INFO 8 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
+2023-11-27T07:51:48.177Z  INFO 8 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 747 ms
+2023-11-27T07:51:48.459Z  INFO 8 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port 8080 (http) with context path ''
+2023-11-27T07:51:48.471Z  INFO 8 --- [           main] com.example.springboot.Application       : Started Application in 1.433 seconds (process running for 1.673)
+Picked up JAVA_TOOL_OPTIONS:  -XX:+ExitOnOutOfMemoryError
+8:
+2023-11-27T07:51:57.048Z  INFO 8 --- [Attach Listener] jdk.crac                                 : Starting checkpoint
+CR: Checkpoint ...
+/application/entrypoint.sh: line 13:     8 Killed                  java -XX:CRaCCheckpointTo=$CHECKPOINT_RESTORE_FILES_DIR org.springframework.boot.loader.launch.JarLauncher
+2023-11-27T07:52:00.491Z  INFO 8 --- [Attach Listener] o.s.c.support.DefaultLifecycleProcessor  : Restarting Spring-managed lifecycle beans after JVM restore
+2023-11-27T07:52:00.494Z  INFO 8 --- [Attach Listener] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port 8080 (http) with context path ''
+2023-11-27T07:52:00.495Z  INFO 8 --- [Attach Listener] o.s.c.support.DefaultLifecycleProcessor  : Spring-managed lifecycle restart completed (restored JVM running for 30 ms)
+```
+
+Stop the docker with Ctrl+C, and run the same image again with the same command. This time, logs like the following will be outputted due to the restore. You can see that the JVM starts very quickly.
+
+```
+Restore checkpoint from /var/crac
+2023-11-27T07:52:19.196Z  INFO 8 --- [Attach Listener] o.s.c.support.DefaultLifecycleProcessor  : Restarting Spring-managed lifecycle beans after JVM restore
+2023-11-27T07:52:19.199Z  INFO 8 --- [Attach Listener] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port 8080 (http) with context path ''
+2023-11-27T07:52:19.200Z  INFO 8 --- [Attach Listener] o.s.c.support.DefaultLifecycleProcessor  : Spring-managed lifecycle restart completed (restored JVM running for 32 ms)
+```

entrypoint.sh

@@ -0,0 +1,24 @@
+#!/bin/bash
+mkdir -p $CHECKPOINT_RESTORE_FILES_DIR
+export JAVA_TOOL_OPTIONS="${JAVA_TOOL_OPTIONS} -XX:+ExitOnOutOfMemoryError"
+
+if [ -z "$(ls $CHECKPOINT_RESTORE_FILES_DIR/core-*.img 2>/dev/null)" ]; then
+  echo "Save checkpoint to $CHECKPOINT_RESTORE_FILES_DIR" 1>&2
+  java -XX:CRaCCheckpointTo=$CHECKPOINT_RESTORE_FILES_DIR org.springframework.boot.loader.launch.JarLauncher &
+  sleep ${SLEEP_BEFORE_CHECKPOINT:-10}
+  jcmd org.springframework.boot.loader.launch.JarLauncher JDK.checkpoint
+  sleep ${SLEEP_AFTER_CHECKPOINT:-3}
+else
+  echo "Restore checkpoint from $CHECKPOINT_RESTORE_FILES_DIR" 1>&2
+fi
+
+(echo 128 > /proc/sys/kernel/ns_last_pid) 2>/dev/null || while [ $(cat /proc/sys/kernel/ns_last_pid) -lt 128 ]; do :; done
+java -XX:CRaCRestoreFrom=$CHECKPOINT_RESTORE_FILES_DIR &
+JAVA_PID=$!
+
+stop_java_app() {
+    kill -SIGTERM $JAVA_PID
+}
+
+trap stop_java_app SIGINT
+wait $JAVA_PID