monitor_http.go

package main

import (
	"crypto/tls"
	"github.com/sirupsen/logrus"
	"io/ioutil"
	"net/http"
	"regexp"
	"time"
)

type HttpMonitor struct {
	config     ConfigComponent
	bodyRegexp *regexp.Regexp
}

func NewHttpMonitor(config ConfigComponent) *HttpMonitor {
	bodyRegexp, _ := regexp.Compile(config.Http.Expected.Body)
	return &HttpMonitor{
		config:     config,
		bodyRegexp: bodyRegexp,
	}
}

func (m *HttpMonitor) Config() *ConfigComponent {
	return &m.config
}

func (m *HttpMonitor) Measure() (Datapoint, error) {
	req, err := http.NewRequest(m.config.Http.Method, m.config.Http.Url, nil)
	if err != nil {
		return Datapoint{}, err
	}
	for k, v := range m.config.Http.Headers {
		req.Header.Add(k, v)
	}

	transport := http.DefaultTransport.(*http.Transport)
	transport.TLSClientConfig = &tls.Config{InsecureSkipVerify: m.config.Http.Insecure}
	client := &http.Client{
		Timeout:   time.Duration(m.config.LatencyThresholds.Down) * time.Millisecond,
		Transport: transport,
	}

	before := time.Now()
	resp, err := client.Do(req)
	after := time.Now()
	latency := int(after.Sub(before).Nanoseconds() / 1000000)
	if err != nil {
		logrus.Infof("Monitor %s: %s", err.Error())
		return Datapoint{
			Time:    after,
			Up:      false,
			Latency: latency,
		}, nil
	}

	defer resp.Body.Close()

	if m.config.Http.Expected.StatusCode > 0 && resp.StatusCode != m.config.Http.Expected.StatusCode {
		logrus.Infof("Monitor %s: Expected HTTP response status: %d, got: %d", m.config.Name, m.config.Http.Expected.StatusCode, resp.StatusCode)
		return Datapoint{
			Time:    after,
			Up:      false,
			Latency: latency,
		}, nil
	}

	if m.bodyRegexp != nil {
		// check response body
		responseBody, err := ioutil.ReadAll(resp.Body)
		if err != nil {
			return Datapoint{}, err
		}

		if !m.bodyRegexp.Match(responseBody) {
			logrus.Infof("Monitor %s: Unexpected body: %\nExpected to match: %s", m.config.Name, string(responseBody), m.config.Http.Expected.Body)
			return Datapoint{
				Time:    after,
				Up:      false,
				Latency: latency,
			}, nil
		}
	}

	return Datapoint{
		Time:    after,
		Up:      true,
		Latency: latency,
	}, nil
}