Update java-spring-boot example

Examples/java-spring-boot/Dockerfile

@@ -1,7 +1,4 @@
-FROM openjdk:11
-
-RUN apt-get update && \
-    apt-get install -y openjdk-11-jdk
+FROM openjdk:21-jdk-slim
 
 COPY spring-boot-web-service/build/libs/spring-boot-web-service-0.0.1-SNAPSHOT.jar .
 

Examples/java-spring-boot/README.md

@@ -9,71 +9,69 @@ runs inside the SGX enclave. For more information on Spring Boot, please visit h
 * Tested on:
   - Type: Azure Confidential Computing SGX Virtual Machine
   - Size: Standard DC1s v3 (1 vCPU, 8 GiB memory)
-  - OS: Linux (Ubuntu 20.04)
+  - OS: Linux (Ubuntu 24.04)
 
-* Install the OpenJDK 11 package so that Gradle can consume the files:
+* Install the OpenJDK 21 package so that Gradle can consume the files:
 
     ```bash
-    $ sudo apt-get install openjdk-11-jdk
+    sudo apt-get install openjdk-21-jdk
     ```
 
-* Follow the installation guide at https://gradle.org/install/ to install Gradle v7.6.
+* Follow the installation guide at https://gradle.org/install/ to install Gradle v8.12.
 
 ## Build and run graminized Docker image
 
 1. Build a project using Gradle:
 
 ```bash
-$ (cd spring-boot-web-service/ && gradle build)
+(cd spring-boot-web-service/ && gradle build)
 ```
 
 2. Build Docker image:
 
 ```bash
-$ docker build -t openjdk-11-java-spring-boot .
+docker build -t openjdk-21-java-spring-boot .
 ```
 
 3. Clean up files that will be no longer used:
 
 ```bash
-$ (cd spring-boot-web-service/ && gradle clean)
+(cd spring-boot-web-service/ && gradle clean)
 ```
 
 4. Graminize the Docker image (this step can take some time!):
 
 ```bash
-$ (cd ../.. && ./gsc build openjdk-11-java-spring-boot \
-    Examples/java-spring-boot/java-spring-boot.manifest \
-    -c <PATH-TO-CONFIG-FILE>)
+(cd ../.. && ./gsc build openjdk-21-java-spring-boot \
+    Examples/java-spring-boot/java-spring-boot.manifest)
 ```
 
 5. Sign the graminized Docker image:
 
 ```bash
-$ (cd ../.. && ./gsc sign-image openjdk-11-java-spring-boot \
-    <PATH-TO-KEY-FILE> \
-    -c <PATH-TO-CONFIG-FILE>)
+(cd ../.. && ./gsc sign-image openjdk-21-java-spring-boot \
+    <PATH-TO-KEY-FILE>)
 ```
 
 6. Run graminized image (the application may take a while to load):
 
       * On the default port set to 8080:
 
         ```bash
-        $ docker run --rm --device=/dev/sgx_enclave \
+        docker run --rm --device=/dev/sgx_enclave \
             -v /var/run/aesmd/aesm.socket:/var/run/aesmd/aesm.socket \
             -p 8080:8080 \
-            -d gsc-openjdk-11-java-spring-boot
+            -d gsc-openjdk-21-java-spring-boot
         ```
 
       * On a customized port using an environment variable, e.g. 9080:
 
         ```bash
-        $ docker run --rm --device=/dev/sgx_enclave \
+        docker run --rm --device=/dev/sgx_enclave \
             -v /var/run/aesmd/aesm.socket:/var/run/aesmd/aesm.socket \
             -e SERVER_PORT=9080 \
             -p 9080:9080 \
-            -d gsc-openjdk-11-java-spring-boot
+            -d gsc-openjdk-21-java-spring-boot
         ```
 
 
@@ -82,11 +80,11 @@ $ (cd ../.. && ./gsc sign-image openjdk-11-java-spring-boot \
    Boot application":
 
 ```bash
-$ wget -qO- localhost:<port>
+wget -qO- localhost:<port>
 ```
 
 8. To stop the graminized container with Spring-Boot application, run the command:
 
 ```bash
-$ docker stop <containerID>
+docker stop <containerID>
 ```