Drop support for Ubuntu 14.04 / 16.04 / CentOS 7 on Bazel@HEAD

[davido]

Considering that Ubuntu 16.04 LTS is EOL now, it might be reasonable to drop support for Ubuntu 14.04 / 16.04 / CentOS 7 on Bazel's main branch.

One reason to discontinue support for outdated platforms, is that Bazel@HEAD cannot be built on modern platforms, like Fedora 34 rawhide (x86_64) that switched to gcc 11.x toolchain (https://gcc.gnu.org/gcc-11/), see #12702.

The attempt to bump transitive dependencies in Bazel for gRPC and absl caused the build to fail on outdated CentOS 7 platform due to outdated 4.8.5 C++ compiler toolchain:

  $ docker run -it gcr.io/bazel-public/centos7-java8:latest /bin/bash
  $ gcc --version
  gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-44)

See CI breakages for this PR: #13536.

[davido]

@philwo

To increase the visibility, should this issue be rather transferred to bazel project?

[philwo]

@davido Thanks! I transferred the issue to the Bazel project.

[philwo]

I sent a mail to bazel-discuss@ to get feedback on this: https://groups.google.com/g/bazel-discuss/c/xXkCsFjosG8

[Mizux]

TLDR: With Centos-7 you can have a recent gcc (9) with an "old" glibcxx while ubuntu pull the libstdc++ 3.4.28

You can have a gcc 9 on Centos 7 using this:
https://github.com/google/or-tools/blob/b37d9c786b69128f3505f15beca09e89bf078a89/tools/docker/centos-7.Dockerfile#L12-L20 and still have a good old glibcxx

It can be a good idea to keep centos-7 since it is the image used by manylinux2010 to build native python package (e.g. Google OR-Tools with our SWIG python wrapper (ed currently using the Make or CMake based build system since we don't have swig machinery in bazel yet)).
note: centos-6 use a now forbidden system call so docker image won't work on any recent distro/glinux etc...

And unfortunately Ubuntu ppa toolchain-r pull 3.4.28 -_-

distro	GCC	GLIBC	GLIBCXX
Ubuntu 16.04 LTS	5.4.0	2.23	3.4.21
Ubuntu 16.04 LTS + gcc-7	7.5.0	2.23	3.4.28
Ubuntu 16.04 LTS + gcc-9	9.3.0	2.23	3.4.28
Ubuntu 18.04 LTS	7.5.0	2.27	3.4.25
Centos 7	4.8.5	2.17	3.4.19
Centos 7 + gcc-9	9.3.1	2.17	3.4.19
Centos 8	8.3.1	2.28	3.4.25
Debian 9	6.3.0	2.24	3.4.22
Debian 10	8.3.0	2.28	3.4.25

note: ubuntu-toolchain-r seems to pull libstdc++ 28 -_-

note:
gcc --version
find / -type f -iname "libstdc++*.so*"
find / -type f -iname "libc*.so*"
objdump -p libXXX.so

ref: google/or-tools#2520 (comment)

[davido]

@Mizux

Thanks for your comments. Especially the pointer to CentOS 7 with gcc 9 toolchain.

I have extracted a minimal CentOS 7 with gcc 9 toolchain Dockerfile: [1], created docker image from it and verified, that I can build Bazel with my PR included, where gPRC and Abseil were bumped to recent releases.

This brings us to another possible approach, that I tried to outline in another request: [2] Preserve the outdated platforms, but raise C++ compiler baseline.

WDYT?

[1] https://github.com/davido/centos7-gcc-9-bazel-docker/blob/master/Dockerfile
[2] bazelbuild/continuous-integration#1167

[meteorcloudy]

This is already fixed. We have dropped support for vanilla CentOS 7, instead we now build / test on CentOS 7 with devtoolset-10 (gcc version is 10.2.1). We no longer test on Ubuntu 14.04 and 16.04.