[plugins] Use relative paths or env variables in configs DEV-1272

[mikeland73]

Summary

@Lagoja called out that we were using absolute paths in conf files. Since the conf files are checked-in, they need to be env variables or relative paths if the file doesn't support env variables.

I also added services restart which really helped me test this out.

How was it tested?

devbox add nginx apacheHttpd php
devbox services start
curl localhost
curl localhost:8080
curl localhost:8080/index.php

[loreto]

LGTM to get it working properly.

That said, I'm worried that this is easy to mess up by a new plugin writer. Maybe we need to do something like paths are always from the virtenv root and we rewrite them automatically? (so even if you write /foo that becomes {{ .Virtenv }}/foo.

Or something like that; the main point being that it should be hard for plugin writers to get the paths wrong.

[mikeland73]

@loreto I agree, this is fragile. I made a bunch of mistakes doing it as well. The challenge is when to do the rewrite, it can't happen on shell in devbox.d because that code is checked-in.

I think this is good for now, but I'll think of ways to make it less error prone.