metricbeat/module/kubernetes/volume/volume.go

// Licensed to Elasticsearch B.V. under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Elasticsearch B.V. licenses this file to you under
// the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

package volume

import (
	"fmt"

	"github.com/elastic/beats/v7/metricbeat/helper"
	"github.com/elastic/beats/v7/metricbeat/mb"
	"github.com/elastic/beats/v7/metricbeat/mb/parse"
	k8smod "github.com/elastic/beats/v7/metricbeat/module/kubernetes"
	"github.com/elastic/beats/v7/metricbeat/module/kubernetes/util"
	"github.com/elastic/elastic-agent-libs/mapstr"
)

const (
	defaultScheme = "http"
	defaultPath   = "/stats/summary"
)

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() {
	mb.Registry.MustAddMetricSet("kubernetes", "volume", New,
		mb.WithHostParser(hostParser),
		mb.DefaultMetricSet(),
	)
}

// 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
	http        *helper.HTTP
	mod         k8smod.Module
	clusterMeta mapstr.M
}

// 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) {
	http, err := helper.NewHTTP(base)
	if err != nil {
		return nil, err
	}
	mod, ok := base.Module().(k8smod.Module)
	if !ok {
		return nil, fmt.Errorf("must be child of kubernetes module")
	}

	ms := &MetricSet{
		BaseMetricSet: base,
		http:          http,
		mod:           mod,
		clusterMeta:   util.AddClusterECSMeta(base),
	}

	return ms, nil
}

// Fetch methods implements the data gathering and data conversion to the right
// format. It publishes the event which is then forwarded to the output. In case
// of an error set the Error field of mb.Event or simply call report.Error().
func (m *MetricSet) Fetch(reporter mb.ReporterV2) error {
	body, err := m.mod.GetKubeletStats(m.http)
	if err != nil {
		return fmt.Errorf("error doing HTTP request to fetch 'volume' Metricset data: %w", err)
	}

	events, err := eventMapping(body, m.Logger().Named("kubernetes.volume"))
	if err != nil {
		return err
	}
	for _, e := range events {
		event := mb.TransformMapStrToEvent("kubernetes", e, nil)
		if len(m.clusterMeta) != 0 {
			event.RootFields.DeepUpdate(m.clusterMeta)
		}
		isOpen := reporter.Event(event)
		if !isOpen {
			return nil
		}
	}

	return nil
}