Add devcontainer support for building in container

[bergmeister]

See below link for instructions but basically one just needs to have Docker running in Linux mode with file sharing enabled, install the ms-vscode-remote.remote-containers and then just open VS-Code in that folder and use the command to re-open the folder in a container. Because it is early days, one cannot set the default shell to PowerShell yet, but one can define the following user setting to have the shell that is attached to the container starting with PowerShell instead of bash.
"terminal.integrated.shell.linux": "/usr/bin/pwsh",
https://code.visualstudio.com/docs/remote/containers

[TylerLeonhardt]

This is neat! So I see this primarily being useful for running tests, right?

[bergmeister]

You can run tests as well, my personal experience though is that for longer test suites that take several minutes like PSSA is that Invoke-Pester can make the remote connection to the container hang.
For me the primary benefit is to have a dev environment that works out of the boxcontainer, is clean (remember the times when PSES wrote into AppData) and does not touch/mess with my global system. For other, new people coming to the project and just wanting to tweak a small portion of C# code, it will be a blessing as well. I haven't looked at whether all the other commands or F5 work, I just attach a shell and run Invoke-Build for the moment. I plan to write a blog post (probably have time for that only in 1.5 weeks though) on the feature generally as I got .devcontainer support already into the main PowerShell repo. We had to disable the red-herring codacy flag though (because the no-install-recommends option is actually used on apt-get install but is not available on apt-get update)

[bergmeister]

Sorry, for the many, intermittent pushes, I am done now and fully rebuilt the container just to double check it is still working. Not sure about the current build failures though

[TylerLeonhardt]

Sorry this took so long... I think we should use the new SDK image that has PowerShell installed and also use the Preview extension instead.

[TylerLeonhardt]

If you target the new .NET Core 3.0+ SDK container it contains PowerShell and you won't need to install it.

[bergmeister]

I agree but before that the main build needs to move .net core 3 (I vaguely remember the build to not work with it, but maybe that was an issue with one of the previews)

[TylerLeonhardt]

Gooood point. Looks like that is the case: #1095

Maybe we can try to get that figured out first before this goes in? My team put in work to get PowerShell inside the SDK container - I'd love to leverage that if possible as a form of dogfooding it.

[TylerLeonhardt]

@rjmholt abandoned that PR so I'm ok with this going in as is. When we move to .NET SDK 3.0, we can revisit changing the container.

[TylerLeonhardt]

Next do vscode-powershell!