Adding a second Dockerfile supporting C++20 for cmake C++20 tests

[dabangarang]

This pull request is a response to issue #148.
I added in support to run cmake.c++20.test within a new docker container that is based off Ubuntu 20.04 and supports C++20 and g++-10. This docker container will automatically be built and run when it is specified that cmake.c++20.test is to be run. Other tests will be run on the standard Docker container, which runs on Ubuntu 18.04, as C++ 20 is not needed for these tests.

[linux-foundation-easycla]

The committers are authorized under a signed CLA.

• ✅ Daniel Bang (84d19f3, 4a9955d, 963f226, 0c51c92, 14b6945)

[codecov]

Codecov Report

Merging #211 into master will not change coverage.
The diff coverage is n/a.

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  Coverage   93.94%   93.94%           
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  Lines        6538     6538           
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  Hits         6142     6142           
  Misses        396      396           

[lalitb]

Just wondering, it could have done in single Dockerfile - i..e, installing both gcc-48 and gcc-10 version in ubuntu18 docker container. This can be done by creating ci/install-gcc10.sh with below contents

apt-get -y install software-properties-common
add-apt-repository -y ppa:ubuntu-toolchain-r/test
apt-get -y update
apt install -y gcc-10
apt install -y g++-10

And then while running cmake on tests, set CC/CXX to point to correct compiler.

[dabangarang]

@lalitb apologies for the accidental early commit. I had revised my pull request to implement your suggestion, and the current commit should reflect this. Where/what parameters would I need to change in the do_ci.sh file to identify a different compiler for Cmake20? It seems as though simply changing c++ vesrion to 20 does not change GNU compiler to a compatible version.

[maxgolov]

You don't necessarily need to build a custom docker image. As Ubuntu-20.04 is readily available on GitHub Actions.

You can use GitHub Actions matrix build feature to build with older and newer Ubuntu as follows:

https://raw.githubusercontent.com/maxgolov/opentelemetry-cpp/master/.github/workflows/build-ubuntu.yml

[maxgolov]

It's probably adding considerable amount of CI time to build an image. Have you considered running the ci scripts without a docker, to deploy the tools in one of the readily available GitHub Action images?
https://raw.githubusercontent.com/maxgolov/opentelemetry-cpp/master/.github/workflows/build-ubuntu.yml
Main idea is that total compute and run time for each PR is going to be less, since you won't need to build an image.

[reyang]

@danielbang907, please address comments from @maxgolov and get the CI pass.

[reyang]

This PR is stale, closing for now. @danielbang907 please feel free to reopen it if you have time to work on it.