Fix failing unit test

[GeorgianaElena]

The unit test were failing because of the latest grpcio version 1.28.0, that switches to manylinux2010 (see this announcement for details) (grpcio is a requirement of the etcd3 python client used by traefik-proxy).

I tried a clean install of TLJH on DO and everything went ok, so referring to the info in the announcement I guess it has something to do with the Ubuntu Docker image and the libs there.

[manics]

It's because the default version of pip on Ubuntu 18.04 is too old:

$ docker run -it --rm ubuntu:18.04

root@68cd6b2855c2:/# apt-get update --yes && apt-get install --yes python3 python3-venv
root@68cd6b2855c2:/# python3 -m venv /srv/venv
root@68cd6b2855c2:/# /srv/venv/bin/pip --version
pip 9.0.1 from /srv/venv/lib/python3.6/site-packages (python 3.6)

The alternative to pinning grpcio is to upgrade pip inside the venv

root@68cd6b2855c2:/# /srv/venv/bin/pip install -U pip
root@68cd6b2855c2:/# /srv/venv/bin/pip --version
pip 20.0.2 from /srv/venv/lib/python3.6/site-packages/pip (python 3.6)
root@68cd6b2855c2:/# /srv/venv/bin/pip install grpcio
...
Successfully installed grpcio-1.28.1 six-1.14.0

I don't know what's best.

[GeorgianaElena]

That's what was my first guess too. But TLJH got installed successfully on Digital Ocean using the same old pip:

I think this line in their announcement might explain why it works:
Once the transition happens, if the version of pip is lower than 19, it might result in downloading a source package and building it from source instead of downloading pre-built package.

They also mention the need of glibc being at least 2.12 and libstdc++ at least 6.0.13, but versions inside the docker container seem ok:

So I'm not really sure what's the difference with the Docker image that causes this.

[yuvipanda]

Thank you so much for investigating and getting to the root cause of this, @GeorgianaElena!

I think upgrading pip is a good idea anyway - although I like to pin it rather than just do a --upgrade pip. How does that sound? That's probably a better longer term fix than pinning grpcio, although that also works if that's the easier thing to do.

[GeorgianaElena]

@yuvipanda, upgrading pip is definitely a good idea.
I just added a new commit that:

• upgrades pip inside the hub env
• upgrades pip inside the unit test docker container

What do you think?

[yuvipanda]

Awesome! This looks great to me. Thank you for fixing the tests!