image.go

package image

import (
	"github.com/elastic/beats/libbeat/common"
	"github.com/elastic/beats/libbeat/logp"
	"github.com/elastic/beats/metricbeat/mb"
	"github.com/elastic/beats/metricbeat/module/docker"

	dc "github.com/fsouza/go-dockerclient"
)

// 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("docker", "image", New); 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
	dockerClient *dc.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("BETA: The docker info metricset is beta")

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

	client, err := docker.NewDockerClient(base.HostData().URI, config)
	if err != nil {
		return nil, err
	}

	return &MetricSet{
		BaseMetricSet: base,
		dockerClient:  client,
	}, 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) {

	images, err := m.dockerClient.ListImages(dc.ListImagesOptions{})
	if err != nil {
		return nil, err
	}

	return eventsMapping(images), nil
}