github.com/aclisp/heapster@v0.19.2-0.20160613100040-51756f899a96/metrics/sinks/monasca/monasca_client.go (about)

     1  // Copyright 2015 Google Inc. All Rights Reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package monasca
    16  
    17  import (
    18  	"bytes"
    19  	"encoding/json"
    20  	"fmt"
    21  	"io"
    22  	"io/ioutil"
    23  	"net/http"
    24  	"net/url"
    25  
    26  	"github.com/golang/glog"
    27  )
    28  
    29  // Client specifies the methods of any client ot the Monasca API
    30  type Client interface {
    31  	SendRequest(method, path string, request interface{}) (int, string, error)
    32  	GetURL() *url.URL
    33  	CheckHealth() bool
    34  }
    35  
    36  // ClientImpl implements the monasca API client interface.
    37  type ClientImpl struct {
    38  	ksClient   KeystoneClient
    39  	monascaURL *url.URL
    40  }
    41  
    42  // SendRequest to the Monasca API, authenticating on the fly.
    43  // Returns 0, "", err if the request cannot be built.
    44  // Returns statusCode, response, nil if communication with the server was OK.
    45  func (monClient *ClientImpl) SendRequest(method, path string, request interface{}) (int, string, error) {
    46  	req, err := monClient.prepareRequest(method, path, request)
    47  	if err != nil {
    48  		return 0, "", err
    49  	}
    50  	statusCode, response, err := monClient.receiveResponse(req)
    51  	if err != nil {
    52  		return 0, "", err
    53  	}
    54  	return statusCode, response, nil
    55  }
    56  
    57  func (monClient *ClientImpl) prepareRequest(method string, path string, request interface{}) (*http.Request, error) {
    58  	// authenticate
    59  	token, err := monClient.ksClient.GetToken()
    60  	if err != nil {
    61  		return nil, err
    62  	}
    63  	// marshal
    64  	var rawRequest io.Reader
    65  	if request != nil {
    66  		jsonRequest, err := json.Marshal(request)
    67  		if err != nil {
    68  			return nil, err
    69  		}
    70  		rawRequest = bytes.NewReader(jsonRequest)
    71  	}
    72  	// build request
    73  	req, err := http.NewRequest(method, monClient.GetURL().String()+path, rawRequest)
    74  	if err != nil {
    75  		return nil, err
    76  	}
    77  	req.Header.Add("Content-Type", "application/json")
    78  	req.Header.Add("X-Auth-Token", token)
    79  	return req, nil
    80  }
    81  
    82  func (monClient *ClientImpl) receiveResponse(req *http.Request) (int, string, error) {
    83  	resp, err := (&http.Client{}).Do(req)
    84  	if err != nil {
    85  		return 0, "", err
    86  	}
    87  	defer resp.Body.Close()
    88  	contents, err := ioutil.ReadAll(resp.Body)
    89  	respString := ""
    90  	if err != nil {
    91  		glog.Warning("Cannot read monasca API's response.")
    92  		respString = "Cannot read monasca API's response."
    93  	} else {
    94  		respString = string(contents)
    95  	}
    96  	return resp.StatusCode, fmt.Sprintf("%s", respString), nil
    97  }
    98  
    99  // GetURL of the Monasca API server.
   100  func (monClient *ClientImpl) GetURL() *url.URL {
   101  	return monClient.monascaURL
   102  }
   103  
   104  // CheckHealth of the monasca API server.
   105  func (monClient *ClientImpl) CheckHealth() bool {
   106  	code, _, _ := monClient.SendRequest("GET", "/", nil)
   107  	return code == http.StatusOK
   108  }
   109  
   110  // NewMonascaClient creates a monasca client.
   111  func NewMonascaClient(config Config) (Client, error) {
   112  	// create keystone client
   113  	ksClient, err := NewKeystoneClient(config)
   114  	if err != nil {
   115  		return nil, err
   116  	}
   117  
   118  	// detect monasca URL
   119  	monascaURL := (*url.URL)(nil)
   120  	if config.MonascaURL != "" {
   121  		monascaURL, err = url.Parse(config.MonascaURL)
   122  		if err != nil {
   123  			return nil, fmt.Errorf("Malformed monasca-url sink parameter. %s", err)
   124  		}
   125  	} else {
   126  		monascaURL, err = ksClient.MonascaURL()
   127  		if err != nil {
   128  			return nil, fmt.Errorf("Failed to automatically detect Monasca service: %s", err)
   129  		}
   130  	}
   131  
   132  	// create monasca client
   133  	client := &ClientImpl{ksClient: ksClient, monascaURL: monascaURL}
   134  	healthy := client.CheckHealth()
   135  	if !healthy {
   136  		return nil, fmt.Errorf("Monasca is not running on the provided/discovered URL: %s", client.GetURL().String())
   137  	}
   138  	return client, nil
   139  }