Fix SNAP 7.0 + Python 3 support

[whatnick]

This is a hands on experiment in getting SNAP installed via Docker. If it works nicely the PR will be marked for review.

[schwankner]

hey cool! let me know when you are ready!

[ciaransweet]

@whatnick @schwankner I'd be interested to see where this has gotten to.

I'm also trying to dockerise snappy with Python 3.6, having no luck, hitting:

Please check the log file '/root/.snap/snap-python/snappy/snappyutil.log'.
        at org.esa.snap.python.PyBridge.configureJpy(PyBridge.java:232)
        at org.esa.snap.python.PyBridge.installPythonModule(PyBridge.java:149)
        at org.esa.snap.rcp.cli.SnapArgsProcessor.processPython(SnapArgsProcessor.java:103)
        at org.esa.snap.rcp.cli.SnapArgsProcessor.process(SnapArgsProcessor.java:49)
        at org.netbeans.modules.sendopts.DefaultProcessor.process(DefaultProcessor.java:202)
        at org.netbeans.spi.sendopts.Option$1.process(Option.java:387)
        at org.netbeans.api.sendopts.CommandLine.process(CommandLine.java:317)
        at org.netbeans.modules.sendopts.HandlerImpl.execute(HandlerImpl.java:62)
        at org.netbeans.modules.sendopts.Handler.cli(Handler.java:69)
        at org.netbeans.CLIHandler.notifyHandlers(CLIHandler.java:234)
        at org.netbeans.core.startup.CLICoreBridge.cli(CLICoreBridge.java:82)
        at org.netbeans.CLIHandler.notifyHandlers(CLIHandler.java:234)
        at org.netbeans.CLIHandler$1.exec(CLIHandler.java:268)
        at org.netbeans.CLIHandler.finishInitialization(CLIHandler.java:447)
        at org.netbeans.MainImpl.finishInitialization(MainImpl.java:256)
        at org.netbeans.Main.finishInitialization(Main.java:92)
        at org.netbeans.core.startup.Main.start(Main.java:316)
        at org.netbeans.core.startup.TopThreadGroup.run(TopThreadGroup.java:123)
        at java.lang.Thread.run(Thread.java:748)
Python configuration error: Python configuration failed.
Command [/usr/bin/python3.6 ./snappyutil.py --snap_home /usr/local/snap --java_module /usr/local/snap/snap/modules/org-esa-snap-snap-python.jar --force --log_file ./snappyutil.log --jvm_max_mem 8G --java_home /usr/local/snap/jre --req_arch amd64]
failed with return code 30.
Please check the log file '/root/.snap/snap-python/snappy/snappyutil.log'.

If you've managed to get Python 3 working, I'd love to know!

[ciaransweet]

For reference, my Dockerfile currently looks like:

FROM ubuntu:bionic-20200311

ENV DEBIAN_FRONTEND=noninteractive

RUN apt-get update && \
    apt-get install -y git gcc libssl-dev make openjdk-8-jdk wget zlib1g-dev \
    build-essential libssl-dev zlib1g-dev libbz2-dev \
    libreadline-dev libsqlite3-dev wget curl llvm libncurses5-dev libncursesw5-dev \
    xz-utils tk-dev libffi-dev liblzma-dev python-openssl git python3-distutils

ENV JDK_HOME /usr/lib/jvm/java-8-openjdk-amd64/
ENV JAVA_HOME $JDK_HOME

RUN apt-get install -y python3.6

COPY response.varfile .
RUN wget http://step.esa.int/downloads/7.0/installers/esa-snap_sentinel_unix_7_0.sh
RUN chmod +x esa-snap_sentinel_unix_7_0.sh
RUN ./esa-snap_sentinel_unix_7_0.sh -q
RUN ln -s /usr/local/snap/bin/gpt /usr/bin/gpt


RUN /usr/local/snap/bin/snappy-conf $(which python)