grafana/pkg/web/render.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handlers to operate on outdated fields.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

73 lines
2.2 KiB
Go

// Copyright 2013 Martini Authors
// Copyright 2014 The Macaron Authors
//
// Licensed under the Apache License, Version 2.0 (the "License"): you may
// not use this file except in compliance with the License. You may obtain
// a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations
// under the License.
package web
import (
"html/template"
"io/fs"
"net/http"
"os"
"path/filepath"
)
// Renderer is a Middleware that injects a template renderer into the macaron context, enabling ctx.HTML calls in the handlers.
// If MACARON_ENV is set to "development" then templates will be recompiled on every request. For more performance, set the
// MACARON_ENV environment variable to "production".
func Renderer(dir, leftDelim, rightDelim string) Middleware {
fs := os.DirFS(dir)
t, err := compileTemplates(fs, leftDelim, rightDelim)
if err != nil {
panic("Renderer: " + err.Error())
}
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
ctx := FromContext(req.Context())
if Env == DEV {
if t, err = compileTemplates(fs, leftDelim, rightDelim); err != nil {
panic("Context.HTML:" + err.Error())
}
}
ctx.template = t
next.ServeHTTP(rw, req)
})
}
}
func compileTemplates(filesystem fs.FS, leftDelim, rightDelim string) (*template.Template, error) {
t := template.New("")
t.Delims(leftDelim, rightDelim)
err := fs.WalkDir(filesystem, ".", func(path string, d fs.DirEntry, e error) error {
if e != nil {
return nil // skip unreadable or erroneous filesystem items
}
if d.IsDir() {
return nil
}
ext := filepath.Ext(path)
if ext != ".html" && ext != ".tmpl" {
return nil
}
data, err := fs.ReadFile(filesystem, path)
if err != nil {
return err
}
basename := path[:len(path)-len(ext)]
_, err = t.New(basename).Parse(string(data))
return err
})
return t, err
}