Addition of Python 3

[GazHank]

Inclusion of Python 3 for Centos and Alpine

FOR REVIEW / TESTING

I've tried to make as small a change as possible, and added Python 3 without removing Python 2, to avoid introducing a breaking change. I don't think the other images require the same updates since they are based upon dockcross images.

[vweevers]

without removing Python 2, to avoid introducing a breaking change

I actually prefer removing Python 2, to get smaller images and avoid inconsistencies in which versions ends up being used.

[GazHank]

without removing Python 2, to avoid introducing a breaking change

I actually prefer removing Python 2, to get smaller images and avoid inconsistencies in which versions ends up being used.

Cool, that's a small tweak for Alpine. I need to double check on centos as I think we would need to make the change in the upstream image, or simply uninstall python 2.

An upsteam change seems unlikely given there havent been any updates for 2 years (from what I can see)

[GazHank]

Hi @vweevers I've dropped Python 2 from the Alpine image, per your suggestion. Removing it from centos looks a little more challenging / risky from what I can see

Given the end result is a little different between the 2 platforms, would you prefer I split this into 2 discrete PRs?

[vweevers]

Removing it from centos looks a little more challenging / risky from what I can see

Perhaps we should then keep that. Removing it won't reduce the size (of the base layers) anyway.

Is there an easy way to disable python 2, or make it so that python resolves to Python 3? So that we won't need another semver-major release later on (if and when we do fully remove Python 2). In any case I'd like to test that latest node-gyp does select Python 3.

Can be done in the same PR, I don't mind.

[vweevers]

Merging as-is, to unblock us. If CentOS requires a fix (but I believe it will work) we can do so in a follow-up release. I'll test that on a native addon that I'm releasing today (which uses most of the images here, including CentOS).

Thanks!

[vweevers]

Oops, when I did a git pull locally I saw I already did this. I completely forgot. Did I also test it? 🤔

diff --git a/centos7-devtoolset7/Dockerfile b/centos7-devtoolset7/Dockerfile
index 1c9b1de..7ce1264 100644
--- a/centos7-devtoolset7/Dockerfile
+++ b/centos7-devtoolset7/Dockerfile
@@ -5,8 +5,13 @@ USER 0
 RUN groupadd -g 1000 node && useradd -g 1000 -u 1000 -m node && \
   groupadd -g 2000 travis && useradd -g 2000 -u 2000 -m travis && \
   curl -fsSL https://rpm.nodesource.com/setup_lts.x | bash - && \
-  yum install -y make nodejs && \
-  npm -v
+  yum install -y make nodejs python3 && \
+  sed -i 's/#!\/usr\/bin\/python/#!\/usr\/bin\/python2/' /usr/bin/yum && \
+  ln -sf python3 /usr/bin/python && \
+  yum clean all && \
+  rm -rf /var/cache/yum && \
+  npm -v && \
+  python --version

[vweevers]

I'm reverting the main branch and opening a new PR.