node.go

package node

import (
	"fmt"
	"net/http"

	"github.com/elastic/beats/libbeat/common"
	"github.com/elastic/beats/libbeat/logp"
	"github.com/elastic/beats/metricbeat/mb"
	"github.com/elastic/beats/metricbeat/mb/parse"
)

const (
	defaultScheme = "http"
	defaultPath   = "/pools/default"
)

var (
	hostParser = parse.URLHostParserBuilder{
		DefaultScheme: defaultScheme,
		DefaultPath:   defaultPath,
	}.Build()
)

// init registers the MetricSet with the central registry.
// The New method will be called after the setup of the module and before starting to fetch data
func init() {
	if err := mb.Registry.AddMetricSet("couchbase", "node", New, hostParser); err != nil {
		panic(err)
	}
}

// MetricSet type defines all fields of the MetricSet
// As a minimum it must inherit the mb.BaseMetricSet fields, but can be extended with
// additional entries. These variables can be used to persist data or configuration between
// multiple fetch calls.
type MetricSet struct {
	mb.BaseMetricSet
	client *http.Client
}

// New create a new instance of the MetricSet
// Part of new is also setting up the configuration by processing additional
// configuration entries if needed.
func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
	logp.Warn("EXPERIMENTAL: The couchbase node metricset is experimental")

	config := struct{}{}

	if err := base.Module().UnpackConfig(&config); err != nil {
		return nil, err
	}

	return &MetricSet{
		BaseMetricSet: base,
		client:        &http.Client{Timeout: base.Module().Config().Timeout},
	}, nil
}

// Fetch methods implements the data gathering and data conversion to the right format
// It returns the event which is then forward to the output. In case of an error, a
// descriptive error must be returned.
func (m *MetricSet) Fetch() ([]common.MapStr, error) {
	req, err := http.NewRequest("GET", m.HostData().SanitizedURI, nil)
	if m.HostData().User != "" || m.HostData().Password != "" {
		req.SetBasicAuth(m.HostData().User, m.HostData().Password)
	}

	resp, err := m.client.Do(req)

	if err != nil {
		return nil, fmt.Errorf("error making http request: %v", err)
	}

	defer resp.Body.Close()

	if resp.StatusCode != 200 {
		return nil, fmt.Errorf("Error Connecting to Couchbase %d: %s", resp.StatusCode, resp.Status)
	}

	return eventsMapping(resp.Body), nil
}