grafana/pkg/api/response/web_hack.go
sh0rez 534ece064b
pkg/web: closure-style middlewares (#51238)
* 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handlers to operate on outdated fields.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
2022-08-09 14:58:50 +02:00

78 lines
1.9 KiB
Go

//nolint:unused,deadcode
package response
//NOTE: This file belongs into pkg/web, but due to cyclic imports that are hard to resolve at the current time, it temporarily lives here.
import (
"fmt"
"net/http"
"github.com/grafana/grafana/pkg/models"
"github.com/grafana/grafana/pkg/services/contexthandler/ctxkey"
"github.com/grafana/grafana/pkg/web"
)
type (
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)
)
func wrap_handler(h web.Handler) http.HandlerFunc {
switch handle := h.(type) {
case http.HandlerFunc:
return handle
case handlerStd:
return handle
case handlerStdCtx:
return func(w http.ResponseWriter, r *http.Request) {
handle(w, r, webCtx(w, r))
}
case handlerStdReqCtx:
return func(w http.ResponseWriter, r *http.Request) {
handle(w, r, reqCtx(w, r))
}
case handlerReqCtx:
return func(w http.ResponseWriter, r *http.Request) {
handle(reqCtx(w, r))
}
case handlerReqCtxRes:
return func(w http.ResponseWriter, r *http.Request) {
ctx := reqCtx(w, r)
res := handle(ctx)
if res != nil {
res.WriteTo(ctx)
}
}
case handlerCtx:
return func(w http.ResponseWriter, r *http.Request) {
handle(webCtx(w, r))
}
}
panic(fmt.Sprintf("unexpected handler type: %T", h))
}
func webCtx(w http.ResponseWriter, r *http.Request) *web.Context {
ctx := web.FromContext(r.Context())
if ctx == nil {
panic("no *web.Context found")
}
ctx.Req = r
ctx.Resp = web.Rw(w, r)
return ctx
}
func reqCtx(w http.ResponseWriter, r *http.Request) *models.ReqContext {
wCtx := webCtx(w, r)
reqCtx, ok := wCtx.Req.Context().Value(ctxkey.Key{}).(*models.ReqContext)
if !ok {
panic("no *models.ReqContext found")
}
return reqCtx
}