How to make a binary file executable in Docker with sbt-native-packager?

I need to package a Scala app that handles REST API call and in some cases launches FireFox browser with help of Selenium WebDriver. I use sbt-native-packager, since it's convenient and simple. As a base image I use own Dockerfile:

# https://hub.docker.com/_/debian
FROM openjdk:8-jre-alpine3.9
ARG firefox_ver=70.0
ARG geckodriver_ver=0.26.0

# Download and install deps
RUN apk update && apk add curl curl-dev
# Download and install Firefox
RUN curl -fL -o /tmp/firefox.tar.bz2 https://ftp.mozilla.org/pub/firefox/releases/${firefox_ver}/linux-x86_64/en-GB/firefox-${firefox_ver}.tar.bz2 \
&& tar -xjf /tmp/firefox.tar.bz2 -C /tmp/ && mv /tmp/firefox /usr/local/bin/

# Download and install geckodriver
RUN curl -fL -o /tmp/geckodriver.tar.gz \
https://github.com/mozilla/geckodriver/releases/download/v${geckodriver_ver}/geckodriver-v${geckodriver_ver}-linux64.tar.gz \
&& tar -xzf /tmp/geckodriver.tar.gz -C /tmp/ && chmod +x /tmp/geckodriver && mv /tmp/geckodriver /usr/local/bin/

ENV PATH="/usr/local/bin/firefox:${PATH}"

And then in build.sbt I use following command in order to provide an appropriate access level to the firefox binary:

...
dockerAdditionalPermissions += (DockerChmodType.UserGroupPlusExecute, "/usr/local/bin/firefox/firefox")
...

But unfortunately when I connect to the running docker container and try to call the firefox, I get this:

/opt/docker $ firefox
sh: firefox: Permission denied

As a result, the Scala app is not able to launch FireFox as well :(

Here is permission of the firefox:

-rwxr-xr-x    1 root     root         14656 Oct 16 17:55 firefox

It seems you cannot run (this version of) firefox on Alpine:

# ldd firefox
    /lib64/ld-linux-x86-64.so.2 (0x7fcc15ef4000)
    libpthread.so.0 => /lib64/ld-linux-x86-64.so.2 (0x7fcc15ef4000)
    libdl.so.2 => /lib64/ld-linux-x86-64.so.2 (0x7fcc15ef4000)
    libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x7fcc15d9f000)
    libm.so.6 => /lib64/ld-linux-x86-64.so.2 (0x7fcc15ef4000)
    libgcc_s.so.1 => /usr/lib/libgcc_s.so.1 (0x7fcc15d8b000)
    libc.so.6 => /lib64/ld-linux-x86-64.so.2 (0x7fcc15ef4000)
Error relocating firefox: __fprintf_chk: symbol not found

This seems to be caused by Alpine being based on musl instead of GNU libc.

---

To work around, you could use the firefox package available from Alpine itself (but you would still need the geckodriver to work too)... Alternatively, switch to the non-alpine Docker image.