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Quick reference

支持的标签及相应的 Dockerfile 链接

快速参考（续）

Overview

The images in this repository contain IBM® SDK, Java™ Technology Edition. For more information on the latest version and what's new, see sdk8 on IBM developerWorks and jdk11 on IBM developerWorks. See the license section for restrictions that relate to the use of this image. For more information about IBM® SDK, Java™ Technology Edition and API documentation as well as tutorials, recipes, and Java usage in IBM Cloud, see IBM developerWorks.

Java and all Java-based trademarks and logos are trademarks or registered trademarks of Oracle and/or its affiliates.

Eclipse OpenJ9 Images

Eclipse OpenJ9 is a high performance, scalable, Java virtual machine (JVM) implementation that represents hundreds of person-years of effort. Contributed to the Eclipse project by IBM, the OpenJ9 JVM underpins the IBM SDK, Java Technology Edition product that is a core component of many IBM Enterprise software products. Continued development of OpenJ9 at the Eclipse foundation ensures wider collaboration, fresh innovation, and the opportunity to influence the development of OpenJ9 for the next generation of Java applications. The Eclipse OpenJ9 Docker images are available through AdoptOpenJDK. They are available from here.

Images

There are three types of Docker images here: the Software Developers Kit (SDK), and the Java Runtime Environment (JRE) and a small footprint version of the JRE (SFJ). These images can be used as the basis for custom built images for running your applications.

Small Footprint JRE

The Small Footprint JRE (SFJ) is designed specifically for web developers who want to develop and deploy cloud-based Java applications. Java tools and functions that are not required in the cloud environment, such as the Java control panel, are removed. The runtime environment is stripped down to provide core, essential function that has a greatly reduced disk and memory footprint.

阿尔卑斯 Linux

如果担心整体镜像的大小，请考虑使用 Alpine Linux。Alpine Linux 是 Linux 的一个精简版本，基于 musl libc 和 Busybox，因此 Docker 镜像大小约为 5MB。由于其极小的体积和安装包数量的减少，它的攻击面更小，从而提高了安全性。IBM SDK 依赖于 gnu glibc，源代码可以在这里找到。安装这个库会额外增加 8MB 的镜像大小。下表比较了基于 JRE 版本的 Docker 镜像大小 8.0-3.10 。

JREJRESFJSFJ
 乌班图 阿尔卑斯 乌班图 阿尔卑斯
305 MB184 MB220 MB101 MB

**Note: Alpine Linux is not an officially supported operating system for IBM® SDK, Java™ Technology Edition. **

Multi-Arch Image

Docker Images for the following architectures are now available:

ibmjava now has multi-arch support and so the exact same commands as below works on all supported architectures. This also means that it is no longer necessary to prefix the arch with the image name as that happens auto-magically.

How to use this Image

To run a pre-built jar file with the JRE image, use the following commands: 

FROM ibmjava:jre
RUN mkdir /opt/app
COPY japp.jar /opt/app
CMD ["java", "-jar", "/opt/app/japp.jar"]

You can build and run the Docker Image as shown in the following example: 

docker build -t japp .
docker run -it --rm japp

If you want to place the jar file on the host file system instead of inside the container, you can mount the host path onto the container by using the following commands: 

FROM ibmjava:jre
CMD ["java", "-jar", "/opt/app/japp.jar"]


docker build -t japp .
docker run -it -v /path/on/host/system/jars:/opt/app japp

Using the Class Data Sharing feature

IBM SDK, Java Technology Edition provides a feature called Class data sharing. This mechanism offers transparent and dynamic sharing of data between multiple Java virtual machines (JVMs) running on the same host thereby reducing the amount of physical memory consumed by each JVM instance. By providing partially verified classes and possibly pre-loaded classes in memory, this mechanism also improves the start up time of the JVM.

To enable class data sharing between JVMs that are running in different containers on the same host, a common location must be shared between containers. This requirement can be satisfied through the host or a data volume container. When enabled, class data sharing creates a named "class cache", which is a memory-mapped file, at the common location. This feature is enabled by passing the -Xshareclasses option to the JVM as shown in the following Dockerfile example: 

FROM ibmjava:jre
RUN mkdir /opt/shareclasses
RUN mkdir /opt/app
COPY japp.jar /opt/app
CMD ["java", "-Xshareclasses:cacheDir=/opt/shareclasses", "-jar", "/opt/app/japp.jar"]

The cacheDir sub-option specifies the location of the class cache. For example /opt/sharedclasses. When sharing through the host, a host path must be mounted onto the container at the location the JVM expects to find the class cache. For example: 

docker build -t japp .
docker run -it -v /path/on/host/shareclasses/dir:/opt/shareclasses japp

When sharing through a data volume container, create a named data volume container that shares a volume. 

docker create -v /opt/shareclasses --name classcache japp /bin/true

Then start your JVM container by using --volumes-from flag to mount the shared volume, as shown in the following example: 

docker run -it --volumes-from classcache japp

See Also

See the Websphere-Liberty image, which builds on top of this IBM docker image for Java.

许可证

The Dockerfiles and associated scripts are licensed under the Apache License 2.0.

Licenses for the products installed within the images:

与所有 Docker 镜像一样，这些可能也包含其他可能在其他许可证下的软件（例如基础分发中的 Bash 等，以及包含的主要软件的任何直接或间接依赖项）。

一些能够自动检测到的额外许可信息可能在 repo-info 仓库的 ibmjava/ 目录中找到。

对于任何预构建的镜像使用，使用镜像的用户有责任确保对该镜像的任何使用都符合其中包含的所有软件的相关许可证。