Verify SDKMAN install script. Flush APT and SDKMAN caches to shrinks image size. Formatting.

Author: tw29845

images/java/ubuntu.Dockerfile

@@ -1,23 +1,37 @@
 FROM codercom/enterprise-base:ubuntu
 
-ENV DEBIAN_FRONTEND="noninteractive"
-ENV JAVA_VERSION="21.0.8-tem"
-ENV GRADLE_VERSION="8.14.3"
-ENV MAVEN_VERSION="3.9.11"
-ENV MAVEN_CONFIG="/home/coder/.m2"
+ARG DEBIAN_FRONTEND="noninteractive"
+ARG SDKMAN_SHA512="ade94c3b8454bac9411139a46adbd68a16f05766b9bc6fa7061535bbce353c93578393e46cc0d90c630691774d1057b234134fe7af105e1e649f4e8811794de4"
 
-RUN sudo apt-get update && \
-  sudo apt-get install --yes --no-install-recommends --no-install-suggests zip && \
-  curl -fsSL "https://get.sdkman.io" | bash && \
-  source "/home/coder/.sdkman/bin/sdkman-init.sh" && \
-  sdk version && \
-  sdk install java $JAVA_VERSION && \
-  sdk default java $JAVA_VERSION && \
-  sdk install gradle $GRADLE_VERSION && \
-  sdk default gradle $GRADLE_VERSION && \
-  sdk install maven $MAVEN_VERSION && \
-  sdk default maven $MAVEN_VERSION && \
-  sdk flush && \
-  sdk current java && \
-  sdk current gradle && \
-  sdk current maven
+ENV SDKMAN_DIR="/home/coder/.sdkman" \
+    SDKMAN_CLI_AUTO_CONFIRM=true \
+    JAVA_VERSION="21.0.8-tem" \
+    GRADLE_VERSION="8.14.3" \
+    MAVEN_VERSION="3.9.11" \
+    MAVEN_CONFIG="/home/coder/.m2"
+
+USER root
+
+RUN apt-get update -qq && \
+  apt-get install -qq -y \
+    --no-install-recommends \
+    --no-install-suggests \
+    zip && \
+  rm -rf /var/lib/apt/lists/*
+
+USER coder
+
+RUN curl -fsSL https://get.sdkman.io -o /tmp/install_sdkman.sh && \
+    echo "${SDKMAN_SHA512} /tmp/install_sdkman.sh" | sha512sum -c - && \
+    bash /tmp/install_sdkman.sh && \
+    rm /tmp/install_sdkman.sh && \
+    bash -c "source ${SDKMAN_DIR}/bin/sdkman-init.sh && \
+      sdk install java ${JAVA_VERSION} && \
+      sdk default java ${JAVA_VERSION} && \
+      sdk install gradle ${GRADLE_VERSION} && \
+      sdk default gradle ${GRADLE_VERSION} && \
+      sdk install maven ${MAVEN_VERSION} && \
+      sdk default maven ${MAVEN_VERSION} && \
+      sdk flush archives && \
+      sdk flush temp && \
+      sdk current"