[JAVA] Create a Docker container image with JRE8 / JDK8 on Amazon Linux

background

• Create a container image containing JRE (ver8 for various reasons) on Amazon Linux
• There are various backgrounds in the past and it is 8
• Note that the package names of JDK and JRE are confused.
• Make a note of each image size

JRE container image creation

• Dockerfile for JRE
• Headless is included only in JRE
• Unmarked java-1.8.0-openjdk seems to have a large capacity because it contains icons etc.
• Actually, I think that it is often used in multi-stage builds, but this time I will simplify it and move it with the base image

Dockerfile

FROM amazonlinux:2.0.20181114
RUN yum install -y java-1.8.0-openjdk-headless && yum clean all

• Create an image & (There is an anti-pattern feeling, but enter with ssh) Check the version of java, javac

#Create a Docker container image
$ docker build -t amazonlinux-jre8 .
(abridgement)

#(For confirmation) Enter the container with ssh and check the version
$ docker run -it amazonlinux-jre8 sh
sh-4.2# java -version
openjdk version "1.8.0_191"
OpenJDK Runtime Environment (build 1.8.0_191-b12)
OpenJDK 64-Bit Server VM (build 25.191-b12, mixed mode)
sh-4.2# javac -version
sh: javac: command not found

• You can safely run the java command, but the javac command is (of course) not installed

JDK container image creation

• Dockerfile for JDK
• JDK with devel
• I think that it is often used on the multi-stage build side, but simply check with the base image

Dockerfile

FROM amazonlinux:2.0.20181114
RUN yum install -y java-1.8.0-openjdk-devel && yum clean all

• Create an image as with the JRE version & check the java and javac versions

#Create a Docker container image
$ docker build -t amazonlinux-jdk
(abridgement)

#(For confirmation) Enter the container with ssh and check the version
$ docker run -it amazonlinux-jdk sh
sh-4.2# java -version
openjdk version "1.8.0_191"
OpenJDK Runtime Environment (build 1.8.0_191-b12)
OpenJDK 64-Bit Server VM (build 25.191-b12, mixed mode)
sh-4.2# javac -version
javac 1.8.0_191

• Safely, both java and javac commands are available

Check size

• You can get the image size with the docker images command.
• The difference from the base amazonlinux is caused by the JRE, JDK package size addition command.

$ docker images --format "table {{.Repository}}\t{{.Size}}" | grep amazonlinux
amazonlinux                  162MB
amazonlinux-jre8             308MB
amazonlinux-jdk              362MB

Summary

• When using only JRE java-1.8.0-openjdk-headless
• When using JDK java-1.8.0-openjdk-devel
• The size difference is about 54MB. So when using the JDK, it's better to use a multi-stage build.