Installing Java in Docker image

I was able to install OpenJDK 8 via the steps below (taken from here). My Dockerfile inherits from phusion/baseimage-docker, which is based on Ubuntu 16.04 LTS.

# Install OpenJDK-8
RUN apt-get update && \
    apt-get install -y openjdk-8-jdk && \
    apt-get install -y ant && \
    apt-get clean;
    
# Fix certificate issues
RUN apt-get update && \
    apt-get install ca-certificates-java && \
    apt-get clean && \
    update-ca-certificates -f;

# Setup JAVA_HOME -- useful for docker commandline
ENV JAVA_HOME /usr/lib/jvm/java-8-openjdk-amd64/
RUN export JAVA_HOME

To install OpenJDK 7 instead, you may need to prepend

add-apt-repository ppa:openjdk-r/ppa

such that the first step becomes

# Install OpenJDK-7
RUN add-apt-repository ppa:openjdk-r/ppa && \
    apt-get update && \
    apt-get install -y openjdk-7-jdk && \
    apt-get install -y ant && \
    apt-get clean;