github.com/m3db/m3@v1.5.0/src/query/api/v1/httpd/router.go (about)

     1  // Copyright (c) 2020 Uber Technologies, Inc.
     2  //
     3  // Permission is hereby granted, free of charge, to any person obtaining a copy
     4  // of this software and associated documentation files (the "Software"), to deal
     5  // in the Software without restriction, including without limitation the rights
     6  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     7  // copies of the Software, and to permit persons to whom the Software is
     8  // furnished to do so, subject to the following conditions:
     9  //
    10  // The above copyright notice and this permission notice shall be included in
    11  // all copies or substantial portions of the Software.
    12  //
    13  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    14  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    15  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    16  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    17  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    18  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    19  // THE SOFTWARE.
    20  
    21  // Package httpd contains http routers.
    22  package httpd
    23  
    24  import (
    25  	"net/http"
    26  	"strings"
    27  
    28  	"github.com/m3db/m3/src/query/api/v1/options"
    29  	"github.com/m3db/m3/src/x/headers"
    30  )
    31  
    32  type router struct {
    33  	promqlHandler      func(http.ResponseWriter, *http.Request)
    34  	m3QueryHandler     func(http.ResponseWriter, *http.Request)
    35  	defaultQueryEngine options.QueryEngine
    36  }
    37  
    38  func NewQueryRouter() options.QueryRouter {
    39  	return &router{}
    40  }
    41  
    42  func (r *router) Setup(opts options.QueryRouterOptions) {
    43  	defaultEngine := opts.DefaultQueryEngine
    44  	if defaultEngine != options.PrometheusEngine && defaultEngine != options.M3QueryEngine {
    45  		defaultEngine = options.PrometheusEngine
    46  	}
    47  
    48  	r.defaultQueryEngine = defaultEngine
    49  	r.promqlHandler = opts.PromqlHandler
    50  	r.m3QueryHandler = opts.M3QueryHandler
    51  }
    52  
    53  func (r *router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
    54  	engine := strings.ToLower(req.Header.Get(headers.EngineHeaderName))
    55  	urlParam := req.URL.Query().Get(EngineURLParam)
    56  
    57  	if len(urlParam) > 0 {
    58  		engine = strings.ToLower(urlParam)
    59  	}
    60  
    61  	if !options.IsQueryEngineSet(engine) {
    62  		engine = string(r.defaultQueryEngine)
    63  	}
    64  
    65  	w.Header().Add(headers.EngineHeaderName, engine)
    66  
    67  	if engine == string(options.M3QueryEngine) {
    68  		r.m3QueryHandler(w, req)
    69  		return
    70  	}
    71  
    72  	r.promqlHandler(w, req)
    73  }