[Go] Update expose to allow mounting routes from imported packages

[ewucc]

Adds support for router.Mount() which allows you to import routers from other packages within your application.

r.Get("/", func(w http.ResponseWriter, r *http.Request) {
	w.Write([]byte("Hello from Klotho!"))
})

r.Mount("/extra", routes.ExtraRoutes())

Updated Docs PR: https://github.com/klothoplatform/docs/pull/135
Updated Sample App PR: https://github.com/klothoplatform/GoSampleApps/pull/1/files

Standard checks

• Unit tests: Any special considerations?
• Docs: Do we need to update any docs, internal or public?
• Backwards compatibility: Will this break existing apps? If so, what would be the extra work required to keep them working?

[github-actions]

Package	Line Rate	Health
github.com/klothoplatform/klotho/pkg/analytics	2%	❌
github.com/klothoplatform/klotho/pkg/annotation	24%	❌
github.com/klothoplatform/klotho/pkg/core	21%	❌
github.com/klothoplatform/klotho/pkg/env_var	82%	✔
github.com/klothoplatform/klotho/pkg/exec_unit	41%	❌
github.com/klothoplatform/klotho/pkg/infra/kubernetes	58%	➖
github.com/klothoplatform/klotho/pkg/infra/kubernetes/helm	52%	➖
github.com/klothoplatform/klotho/pkg/input	63%	➖
github.com/klothoplatform/klotho/pkg/lang	37%	❌
github.com/klothoplatform/klotho/pkg/lang/dockerfile	0%	❌
github.com/klothoplatform/klotho/pkg/lang/golang	19%	❌
github.com/klothoplatform/klotho/pkg/lang/javascript	46%	❌
github.com/klothoplatform/klotho/pkg/lang/python	60%	➖
github.com/klothoplatform/klotho/pkg/lang/yaml	0%	❌
github.com/klothoplatform/klotho/pkg/logging	7%	❌
github.com/klothoplatform/klotho/pkg/multierr	95%	✔
github.com/klothoplatform/klotho/pkg/provider/aws	60%	➖
github.com/klothoplatform/klotho/pkg/runtime	75%	✔
github.com/klothoplatform/klotho/pkg/static_unit	32%	❌
github.com/klothoplatform/klotho/pkg/validation	73%	➖
Summary	42% (3661 / 8714)	❌

[jhsinger-klotho]

this is still limited to the same file as the listen call right?

[ewucc]

when checking for external calls, we no longer care about the listen. So we're just getting the package name of the mounted package and finding the file where the routes are defined. It's no longer in the main.go file w/ the listen anymore. Not sure if that answered your question

[jhsinger-klotho]

this is only run when a file has annotations though and weve found the listener. Im not sure if go allows the routes to be in a separate file, but is that working? Im not sure if your answer is clear to me, im a little confused

[jhsinger-klotho]

do we want to be returning errors from this plugin? Like at this point are we certain they meant to match the go chi syntax for us? If we ever supported another expose library for go would this get confusing?

[ewucc]

yeh i was kind of on the fence. I didn't put as many errors in the first time around since we could technically just silently continue if we don't find what we expect. At this point though, yeh we have determined that there is a mount call to an external package, but we cannot find the package in the imports. Though if this were to happen, the go build for the project just wouldn't work either.

[jhsinger-klotho]

alright yeah thats fine then i guess, can always remove it