`pkg/web` triggers a panic when a http handler chain does not return any
response to the client.
This has been put in place, because it usually means a middleware along
the way did not call the next one.
In this specific case however, the handlers meant to return 200, but did
not do so explicitely, instead relying on the default behavior of `net/http`
* pkg/web: closure-style middlewares
Switches the middleware execution model from web.Handlers in a slice to
web.Middleware.
Middlewares are temporarily kept in a slice to preserve ordering, but
prior to execution they are applied, forming a giant call-stack, giving
granular control over the execution flow.
* pkg/middleware: adapt to web.Middleware
* pkg/middleware/recovery: use c.Req over req
c.Req gets updated by future handlers, while req stays static.
The current recovery implementation needs this newer information
* pkg/web: correct middleware ordering
* pkg/webtest: adapt middleware
* pkg/web/hack: set w and r onto web.Context
By adopting std middlewares, it may happen they invoke next(w,r) without
putting their modified w,r into the web.Context, leading old-style
handlers to operate on outdated fields.
pkg/web now takes care of this
* pkg/middleware: selectively use future context
* pkg/web: accept closure-style on Use()
* webtest: Middleware testing
adds a utility function to web/webtest to obtain a http.ResponseWriter,
http.Request and http.Handler the same as a middleware that runs would receive
* *: cleanup
* pkg/web: don't wrap Middleware from Router
* pkg/web: require chain to write response
* *: remove temp files
* webtest: don't require chain write
* *: cleanup
* pkg/web: store http.Handler internally
* pkg/web: remove injection
Removes any injection code from pkg/web.
It already was no longer functional, as we already only injected into
`http.Handler`, meaning we only inject ctx.Req and ctx.Resp.
Any other types (*Context, *ReqContext) were already accessed using the
http.Request.Context.Value() method.
* *: remove type mappings
Removes any call to the previously removed TypeMapper, as those were
non-functional already.
* pkg/web: remove Context.Invoke
was no longer used outside of pkg/web and also no longer functional
Makes `pkg/web` only accept handles from the following set:
```go
handlerStd = func(http.ResponseWriter, *http.Request)
handlerStdCtx = func(http.ResponseWriter, *http.Request, *web.Context)
handlerStdReqCtx = func(http.ResponseWriter, *http.Request, *models.ReqContext)
handlerReqCtx = func(*models.ReqContext)
handlerReqCtxRes = func(*models.ReqContext) Response
handlerCtx = func(*web.Context)
```
This is a first step to reducing above set to only `http.Handler`.
---
Due to a cyclic import situation between `pkg/models` and `pkg/web`, parts of this PR were put into `pkg/api/response`, even though they definitely do not belong there. This however is _temporary_ until we untangle `models.ReqContext`.
sh0rez