include python 3 in the build image

[DanAlbert]

Is your feature request related to a problem? Please describe. The docker image the builder's use is ubuntu 16.04 based, which it seems didn't have python 3 installed by default. I know jitpack is primarily focused on Java-family languages, but it's also for Android, and Android builds often include native code built by CMake. Some CMake builds will shell out some of their work to Python. If those android libraries want to be buildable by jitpack, they currently have to remain on (or downgrade to) python 2.

Describe the solution you'd like Python 3 (preferably the latest available) installed on the build image.

Describe alternatives you've considered Being able to install python3 in before_install would also work (the build unsurprisingly does not run as root, and sudo is not available), or being able to specify a custom dockerfile for the build.

Additional context https://github.com/DanAlbert/Vulkan-ValidationLayers/tree/jitpack is the project I'm trying to add jitpack support for. It's more complicated than the more common case I mention above of CMake shelling out to Python. This project is built by a python script that calls CMake for each Android ABI, but the resulting artifact is still an AAR. Converting the project to build with Gradle is quite difficult because it's a cross-platform project and it's probably not agreeable to disconnect the Android build workflow from the workflow for other platforms. Their pre-build step for installing build dependencies is also written in Python, so even if the Android build were converted to Gradle, the build would still need Python.

[github-actions[bot]]

This issue is stale because it has been open for 30 days with no activity.

[DanAlbert]

Still a problem afaik.