feat: make RR embeddable in other programs

[khepin]

Reason for This PR

Where I work, go based apps run inside a go service container. This is a set of middleware, libraries, framework like constructs that are shared across all go apps within the organization. It handles a great deal of authn / authz concerns, shipping logs to the right place, basic telemetry etc....

On the way out, it also enhances the response with some required headers.

To do all these things it assumes that it is first in line when an HTTP request arrives.

We're trying to enable PHP / RoadRunner apps in this infrastructure while still benefitting from the years of company specific work, built into this Go container. To do this we need to

• embed RoadRunner inside of this company service container and run it from that process
• get hold of the HTTP plugin so we can use it to pass *http.Request instances to it and get the responses

Looking for feedback
At this point, I'm looking for feedback from the RR team on this. Because of this, I have not yet added documentation etc...
I would first like to validate that this approach is acceptable for the team before I put more effort into it.

Description of Changes

Changes here

• bring a new type roadrunner.RoadRunner (to be changed?) that holds everything required to start and stop a roadrunner instance from code.
• The rr serve command is updated to make use of this new code
• The list of plugins to be used is passed as an argument to roadrunner.New this allows the caller to hold on to some of the plugins that need to be accessed in other parts of the application.

rrHttp := &httpPlugin.Plugin{}
plugins := []interface{}{
    &informer.Plugin{},
    &resetter.Plugin{},
    &logger.Plugin{},
    &metrics.Plugin{},
    &rpcPlugin.Plugin{},
    &server.Plugin{},
    &service.Plugin{},

    // http server plugin
    rrHttp,
}
rr, err := roadrunner.NewRR(*cfgFile, override, plugins)
if err != nil {
    fmt.Println("could not start RR %w", err)
}
go func () {
    rr.Serve()
}()

mockRequest := &http.Request{/*...*/}
responseRecorder := httptest.NewRecorder()
rrHttp.ServeHTTP(responseRecorder, mockRequest)

// ...
// From here on, the Go framework / service container is free to enhance / transform the 
// response in whatever way it needs

License Acceptance

By submitting this pull request, I confirm that my contribution is made under the terms of the MIT license.

PR Checklist

[Author TODO: Meet these criteria.]
[Reviewer TODO: Verify that these criteria are met. Request changes if not]

• All commits in this PR are signed (git commit -s).
• The reason for this PR is clearly provided (issue no. or explanation).
• The description of changes is clear and encompassing.
• Any required documentation changes (code and docs) are included in this PR.
• Any user-facing changes are mentioned in CHANGELOG.md.
• All added/changed functionality is tested.

[codecov]

Codecov Report

Merging #1214 (867b8d1) into master (bb4a2bf) will increase coverage by 1.88%.
The diff coverage is 60.31%.

@@            Coverage Diff             @@
##           master    #1214      +/-   ##
==========================================
+ Coverage   43.00%   44.89%   +1.88%     
==========================================
  Files          13       14       +1     
  Lines         658      715      +57     
==========================================
+ Hits          283      321      +38     
- Misses        354      367      +13     
- Partials       21       27       +6     

Impacted Files	Coverage Δ
container/config.go	74.54% <ø> (ø)
container/container.go	100.00% <ø> (ø)
container/plugins.go	100.00% <ø> (ø)
internal/cli/serve/command.go	5.88% <0.00%> (+0.16%)	⬆️
lib/roadrunner.go	64.40% <64.40%> (ø)

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[rustatian]

Hey @khepin 👋🏻 . Thanks for the PR. That is a good idea to have a RR embeddable in other apps. Some notes here:

1. Since this is standalone functionality, could you please revert the changes in the cli.serve.command.go ? Some other apps (octane for example) depend on silent mode, which you removed (why?).
2. You must install a golangci-lint and fix warnings: https://golangci-lint.run/usage/install/

[rustatian]

Since this is an entirely standalone package inside the roadrunner repo, could you please add go.mod/sum to the roadrunner/roadrunner folder?

EDIT: not needed.

[rustatian]

Ok, that was my bad idea to use a separate go.mod/sum, you won't be able to reuse the internal packages and version with build_time (which is in meta).
Version and buildtime set via -ldflags on the linking phase. But if we use a different package, we won't be able to put them. Sorry for the confusion, but let's remove the go.mod/sum.