Sometimes you need JDK8 in your docker image …

… and depending the base image this may not be available, even from the ppa repositories. Moreover, you cannot download it directly from Oracle without a username / password anymore, so this may break automation, if you do not host your own repositories. Have no fear, sdkman can come to the rescue and fetch for you a supported JDK8 version. You need to pay some extra care with JAVA_HOME and PATH though:

FROM python:3.6-slim
RUN apt-get update && apt-get upgrade -y
RUN apt-get install -y curl zip unzip
RUN curl -fsSL -o
RUN sh ./
RUN bash -c "source /root/.sdkman/bin/ && sdk install java 8.0.212-amzn"
ENV JAVA_HOME=/root/.sdkman/candidates/java/current
CMD bash

Since curl | sudo bash is a topic of contention, do your homework and decide whether you’re going to use it as displayed in the Dockerfile above, or employ some extra verification mechanism of your choice.