github.com/m3db/m3@v1.5.0/src/ctl/service/health/service.go (about)

     1  // Copyright (c) 2017 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 health
    22  
    23  import (
    24  	"encoding/json"
    25  	"fmt"
    26  	"net/http"
    27  	"os"
    28  	"time"
    29  
    30  	mservice "github.com/m3db/m3/src/ctl/service"
    31  	"github.com/m3db/m3/src/x/instrument"
    32  
    33  	"github.com/gorilla/mux"
    34  )
    35  
    36  const (
    37  	ok          healthStatus = "OK"
    38  	healthURL                = "/health"
    39  	unknownName              = "unknown"
    40  )
    41  
    42  type healthStatus string
    43  
    44  type healthCheckResult struct {
    45  	Host         string        `json:"host"`
    46  	Timestamp    time.Time     `json:"timestamp"`
    47  	ResponseTime time.Duration `json:"response_time"`
    48  	Status       healthStatus  `json:"status"`
    49  }
    50  
    51  type service struct {
    52  	iOpts instrument.Options
    53  }
    54  
    55  // NewService creates a new rules controller.
    56  func NewService(iOpts instrument.Options) mservice.Service {
    57  	return &service{iOpts: iOpts}
    58  }
    59  
    60  func (s *service) URLPrefix() string {
    61  	return healthURL
    62  }
    63  
    64  func (s *service) RegisterHandlers(router *mux.Router) error {
    65  	log := s.iOpts.Logger()
    66  	router.HandleFunc("", healthCheck)
    67  	log.Info("registered health endpoints")
    68  	return nil
    69  }
    70  
    71  func (s *service) Close() {}
    72  
    73  func status() healthStatus {
    74  	return ok
    75  }
    76  
    77  func hostName() string {
    78  	host, err := os.Hostname()
    79  	if err != nil {
    80  		host = unknownName
    81  	}
    82  	return host
    83  }
    84  
    85  func healthCheck(w http.ResponseWriter, r *http.Request) {
    86  	start := time.Now()
    87  	host := hostName()
    88  	status := status()
    89  	h := healthCheckResult{Host: host, Timestamp: start, Status: status}
    90  	h.ResponseTime = time.Since(start)
    91  
    92  	body, err := json.Marshal(h)
    93  	if err != nil {
    94  		w.WriteHeader(http.StatusInternalServerError)
    95  		fmt.Fprintf(w, "Could not generate health check result")
    96  		return
    97  	}
    98  
    99  	w.Header().Set("Content-Type", "application/json")
   100  	w.Write(body)
   101  }