CentOS 6 just went EOL at the end of November 2020; as of today, the
repository seems to have disappeared, so our CI builds are failing. This
PR updates us to CentOS 7, which should be usable until June 30, 2024.
* use setuptools_scm for python version management
* add git dep for python wheel building
* if no tag is defined, default to dev
* any untagged version default to 0.0.1
This commit migrates wasmtime's CI infrastructure from Azure Pipelines
to Github Actions. Using Github Actions has a few benefits over other
offerings:
* Being natively integrated with Github means that there's no degree of
user account configuration or access control management, it's all
inherent via already existing Github permissions.
* Github Actions gives 20 parallel builders instead of Azure's 10 by
default, which is a nice boost to have!
Overall I've found Github Actions to feel a bit cleaner than Azure
Pipelines as well. Subjectively I've found the configuration to be more
readable and more pleasant to work with, although they're both just as
"powerful" I think. Additionally Github Actions has been pretty solid in
my own personal testing for a number of other projects.
The main trickiness with wasmtime's CI is the rolling `dev` release of
the master branch as well as binary releases for tags. Github Actions
doesn't have quite as much built in functionality as Azure Pipelines,
but Github Actions does have a nice feature where you can define the
code for an action locally rather than only using built-in actions.
This migration adds three local actions with some associated JS code to
run the action (currently it looks like it basically requires JS)
* An `install-rust` action papers over the gotchas about installing
Rust, allowing Rust installation to be a one-liner in the configuration.
* A `binary-compatible-builds` action allows easily configuring the
wheels and the binaries to be "more binary compatible" and handles
things like compilation flags on OSX and Windows while handling the
`centos:6` container on Linux.
* The `github-release` action is the logic using the `@actions/github`
JS package to orchestrate the custom way we manage rolling releases,
ensuring that a new release is made for the master branch under `dev`
(deleting the previous tag/release ahead of time) and then also
manages tagged releases by uploading them there.
I'm hoping that most of the inline actions here will largely go away.
For example `install-rust` should be simply `rustup update $toolchain`
once various environment issues are fixed on Github Actions runner
images. Additionally `github-release` will ideally migrate to something
like https://github.com/actions/create-release or similar once it has
enough functionality. I'm also hoping that the maintenance in the
meantime of these actions is pretty low-cost, but if it becomes an issue
we can look into other solutions!
