example-spring-boot

This is an example of Spring Boot Getting Started modified to work on OpenJDK CRaC, which consists only in using Spring Boot 3.2+ and adding the org.crac:crac dependency (version 1.4.0 or later).

Building

Use Maven to build

./mvnw package

Running

Please refer to README for details.

If you see an error, you may have to update your criu permissions with

sudo chown root:root $JAVA_HOME/lib/criu
sudo chmod u+s $JAVA_HOME/lib/criu

Preparing the image

1. Run the JDK in the checkpoint mode

$JAVA_HOME/bin/java -XX:CRaCCheckpointTo=cr -jar target/example-spring-boot-0.0.1-SNAPSHOT.jar

2. Warm-up the instance

siege -c 1 -r 100000 -b http://localhost:8080

3. Request checkpoint

jcmd target/example-spring-boot-0.0.1-SNAPSHOT.jar JDK.checkpoint

Restoring

$JAVA_HOME/bin/java -XX:CRaCRestoreFrom=cr

Preparing a container image

1. After building the project locally create an image to be checkpointed.

docker build -f Dockerfile.checkpoint -t example-spring-boot-checkpoint .

2. Start a (detached) container that will be checkpointed. Note that we're mounting target/cr into the container.

docker run -d --rm -v $(pwd)/target/cr:/cr --cap-add=CHECKPOINT_RESTORE --cap-add=SYS_PTRACE -p 8080:8080 --name example-spring-boot-checkpoint example-spring-boot-checkpoint

3. Validate that the container is up and running (here you could also perform any warm-up)

curl localhost:8080
Greetings from Spring Boot!

4. Checkpoint the running container

docker exec -it example-spring-boot-checkpoint jcmd example-spring-boot JDK.checkpoint

5. Build another container image by adding the data from target/cr on top of the previous image and adjusting entrypoint:

docker build -f Dockerfile.restore -t example-spring-boot .

6. (Optional) Start the application in the restored container and validate that it works

docker run -it --rm -p 8080:8080 example-spring-boot
# In another terminal
curl localhost:8080