Java11应用程序作为轻量级docker映像

Question

• 同时，当前稳定的Debian版本仍然没有Java 11软件包（Ubuntu在openjdk-11软件包下安装了Java10)，这就是为什么不稳定的sid版本被用于基本docker映像

当前可用的Oracle openjdk-11映像构建未剥离的libjvm.so模块，该模块具有数百兆字节，必须单独剥离：

• 从openjdk创建的JLink运行时映像大小（特别是libjvm.so）非常大。预期它会小得多。
• 解决方案:https://github.com/docker-library/openjdk/issues/217#issuecomment-436079779

所以问题是：

有哪些优化或推荐的方法来构建和交付作为docker映像的Java11应用程序？

Answer 1

2019.7.UPD:https://stackoverflow.com/A/57145029/907576

作为一个简单的Spring Boot应用程序（只有一个RESTendpoint）的例子，到目前为止，我已经找到了以下解决方案（考虑到应用程序jar位于Docker构建之前的build/libs/spring-boot-demo.jar)：

>

如果我们想在稳定的slim Linux版本上使用Oracle OpenJDK正式发行版(Debian9“Stretch”)的绝地路径：

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# First stage: JDK 11 with modules required for Spring Boot
FROM debian:stretch-slim as packager

# source JDK distribution names
# update from https://jdk.java.net/java-se-ri/11
ENV JDK_VERSION="11.0.1"
ENV JDK_URL="https://download.java.net/java/GA/jdk11/13/GPL/openjdk-${JDK_VERSION}_linux-x64_bin.tar.gz"
ENV JDK_HASH="7a6bb980b9c91c478421f865087ad2d69086a0583aeeb9e69204785e8e97dcfd"
ENV JDK_HASH_FILE="${JDK_ARJ_FILE}.sha2"
ENV JDK_ARJ_FILE="openjdk-${JDK_VERSION}.tar.gz"
# target JDK installation names
ENV OPT="/opt"
ENV JKD_DIR_NAME="jdk-${JDK_VERSION}"
ENV JAVA_HOME="${OPT}/${JKD_DIR_NAME}"
ENV JAVA_MINIMAL="${OPT}/java-minimal"

# downlodad JDK to the local file
ADD "$JDK_URL" "$JDK_ARJ_FILE"

# verify downloaded file hashsum
RUN { \
        echo "Verify downloaded JDK file $JDK_ARJ_FILE:" && \
        echo "$JDK_HASH $JDK_ARJ_FILE" > "$JDK_HASH_FILE" && \
        sha256sum -c "$JDK_HASH_FILE" ; \
    }

# extract JDK and add to PATH
RUN { \
        echo "Unpack downloaded JDK to ${JAVA_HOME}/:" && \
        mkdir -p "$OPT" && \
        tar xf "$JDK_ARJ_FILE" -C "$OPT" ; \
    }
ENV PATH="$PATH:$JAVA_HOME/bin"

RUN { \
        java --version ; \
        echo "jlink version:" && \
        jlink --version ; \
    }

# build modules distribution
RUN jlink \
    --verbose \
    --add-modules \
        java.base,java.sql,java.naming,java.desktop,java.management,java.security.jgss,java.instrument \
        # java.naming - javax/naming/NamingException
        # java.desktop - java/beans/PropertyEditorSupport
        # java.management - javax/management/MBeanServer
        # java.security.jgss - org/ietf/jgss/GSSException
        # java.instrument - java/lang/instrument/IllegalClassFormatException
    --compress 2 \
    --strip-debug \
    --no-header-files \
    --no-man-pages \
    --output "$JAVA_MINIMAL"

# Second stage, add only our minimal "JRE" distr and our app
FROM debian:stretch-slim

ENV JAVA_HOME=/opt/java-minimal
ENV PATH="$PATH:$JAVA_HOME/bin"

COPY --from=packager "$JAVA_HOME" "$JAVA_HOME"
COPY "build/libs/spring-boot-demo.jar" "/app.jar"

EXPOSE 8080
CMD [ "-jar", "/app.jar" ]
ENTRYPOINT [ "java" ]

java-list-modules grep-e“^java\.[^@]*”cut-d@-f 1
java-list-modules grep-e“^jdk\.[^@]*”cut-d@-f 1

在我的例子中，最小7个Spring Boot模块的结果映像大小为123 MB，所有java.*模块的结果映像大小为125 MB

作为此生成工作流的可选改进：

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FROM azul/zulu-openjdk-alpine:11 as packager

RUN { \
        java --version ; \
        echo "jlink version:" && \
        jlink --version ; \
    }

ENV JAVA_MINIMAL=/opt/jre

# build modules distribution
RUN jlink \
    --verbose \
    --add-modules \
        java.base,java.sql,java.naming,java.desktop,java.management,java.security.jgss,java.instrument \
        # java.naming - javax/naming/NamingException
        # java.desktop - java/beans/PropertyEditorSupport
        # java.management - javax/management/MBeanServer
        # java.security.jgss - org/ietf/jgss/GSSException
        # java.instrument - java/lang/instrument/IllegalClassFormatException
    --compress 2 \
    --strip-debug \
    --no-header-files \
    --no-man-pages \
    --output "$JAVA_MINIMAL"

# Second stage, add only our minimal "JRE" distr and our app
FROM alpine

ENV JAVA_MINIMAL=/opt/jre
ENV PATH="$PATH:$JAVA_MINIMAL/bin"

COPY --from=packager "$JAVA_MINIMAL" "$JAVA_MINIMAL"
COPY "build/libs/spring-boot-demo.jar" "/app.jar"

EXPOSE 8080
CMD [ "-jar", "/app.jar" ]
ENTRYPOINT [ "java" ]