Install Groovy in an Alpine-based Docker Image

If you're making a custom image based on an Alpine Linux image, you may have a little trouble installing things that require bash, like Groovy.    I tried using SDKMAN, but unfortunately I encountered a lot of problems with compatibility of unzip, and other tools.   In my case I'm creating an image based on Tomcat and I want Groovy for doing some configuration work.

First, we install the Alpine packages we need:

1. bash
2. curl
3. zip
4. libstdc++ (Gradle needed this, but I don't think Groovy does :shrug:)

RUN apk add --update bash libstdc++ curl zip && \
    rm -rf /var/cache/apk/*

Now we need a workaround for fact that Groovy's shell scripts start with #!/bin/sh :

# Workaround  https://issues.apache.org/jira/browse/GROOVY-7906 and other 'busybox' related issues.
RUN rm /bin/sh && ln -s /bin/bash /bin/sh

Now we can install Groovy. This could probably be done a little more optimally, but it works:

# Install groovy
# Use curl -L to follow redirects
# Also, use sed to make a workaround for https://issues.apache.org/jira/browse/GROOVY-7906
RUN curl -L https://bintray.com/artifact/download/groovy/maven/apache-groovy-binary-2.4.8.zip -o /tmp/groovy.zip && \
    cd /usr/local && \
    unzip /tmp/groovy.zip && \
    rm /tmp/groovy.zip && \
    ln -s /usr/local/groovy-2.4.8 groovy && \
    /usr/local/groovy/bin/groovy -v && \
    cd /usr/local/bin && \
    ln -s /usr/local/groovy/bin/groovy groovy

As always, any suggestions about how to make it better, let me know.