The Holy Grail of a Minimal, Headless, OpenJDK JRE 8

alpine-jre-8

# Build for 206 MB JRE 1.8.0_60 (192 MB in size) with Alping and glibc

FROM alpine:3.2

ENV JRE=jre1.8.0_60 \
    JAVA_HOME=/opt/jre

# That's the an EA from OpenJDK.net 

# Courtesy to https://github.com/frol/docker-alpine-oraclejdk8 from where the setup of glibc is borrowed
RUN apk add --update wget ca-certificates && \
    cd /tmp && \
    wget "https://circle-artifacts.com/gh/andyshinn/alpine-pkg-glibc/6/artifacts/0/home/ubuntu/alpine-pkg-glibc/packages/x86_64/glibc-2.21-r2.apk" \
         "https://circle-artifacts.com/gh/andyshinn/alpine-pkg-glibc/6/artifacts/0/home/ubuntu/alpine-pkg-glibc/packages/x86_64/glibc-bin-2.21-r2.apk" && \
    apk add --allow-untrusted glibc-2.21-r2.apk glibc-bin-2.21-r2.apk && \
    /usr/glibc/usr/bin/ldconfig /lib /usr/glibc/usr/lib && \
    echo 'hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4' >> /etc/nsswitch.conf && \
    mkdir /opt && \
    wget http://www.java.net/download/jdk8u60/archive/b18/binaries/jre-8u60-ea-bin-b18-linux-x64-02_jun_2015.tar.gz -O /tmp/${JRE}.tgz && \
    cd /opt && tar zxvf /tmp/${JRE}.tgz && \
    ln -s /opt/${JRE} /opt/jre && \
    ln -s /opt/jre/bin/java /usr/bin/java && \
    apk del wget ca-certificates && \
    cd /opt/jre/lib/amd64 && rm libjavafx_* libjfx* libfx* && \
    cd /opt/jre/lib/ && rm -rf ext/jfxrt.jar jfxswt.jar javafx.properties font* && \
    rm /tmp/* /var/cache/apk/*

If somebody knows where I can download a .tar of a headless OpenJDK JRE-8, preferred with wget or curl, that would be super awesome.

Yep, got a JDK image with 187 MB with this Dockerfile:

#187 MB JDK image on Alpine + glibc
FROM alpine:3.2

ENV JAVA_HOME=/opt/jdk

# This one is from http://www.linuxfromscratch.org/blfs/view/svn/general/java.html
ADD jdk1.8.0_45.gz /opt

RUN apk add --update wget ca-certificates && \
    cd /tmp && \
    wget "https://circle-artifacts.com/gh/andyshinn/alpine-pkg-glibc/6/artifacts/0/home/ubuntu/alpine-pkg-glibc/packages/x86_64/glibc-2.21-r2.apk" \
         "https://circle-artifacts.com/gh/andyshinn/alpine-pkg-glibc/6/artifacts/0/home/ubuntu/alpine-pkg-glibc/packages/x86_64/glibc-bin-2.21-r2.apk" && \
    apk add --allow-untrusted glibc-2.21-r2.apk glibc-bin-2.21-r2.apk && \
    /usr/glibc/usr/bin/ldconfig /lib /usr/glibc/usr/lib && \
    echo 'hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4' >> /etc/nsswitch.conf && \
    ln -s /opt/OpenJDK-1.8.0.45-bin /opt/jdk && \
    ln -s /opt/jdk/bin/java /usr/bin/java && \
    apk del wget ca-certificates && \
    rm /tmp/* /var/cache/apk/* && \
    rm -rf /opt/jdk/demo /opt/jdk/sample /opt/jdk/man /opt/jdk/src.zip

We are getting closer ;-)

A further optimization of the official build is to avoid the initial ADD and do a direct download, extraction, removal in one single RUN step to avoid the large layer added qith ADD

Also removing JavaFX helps quite a bit.

Image size is now down to 127 MB

Added it to rhuss/docker-java-jolokia

Is there an ARMV6 or ARMV7 of glibc for alpine?

So I'm going to go do some research but maybe someone here knows already?
There seems to be already maintained openjdk packages in the apk repos: https://pkgs.alpinelinux.org/package/community/x86_64/openjdk8

And it requires musl instead of a glibc package -- is it documented anywhere that openjdk and/or oracle jdk require glibc? or one requires one vs the other?

Oracle JDK is not working with musl, see this issue.
Alpine's OpenJDK build seems to be fine with musl (and w/o glibc), I'm running a artifactory instance with it.