internal/vulnerability/fetcher.go

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// 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 vulnerability

import (
	"context"
	"sort"

	"github.com/elastic/cloudbeat/internal/infra/clog"
	"github.com/elastic/cloudbeat/internal/resources/providers/awslib/ec2"
)

type VulnerabilityFetcher struct {
	log      *clog.Logger
	provider instancesProvider
	ch       chan *ec2.Ec2Instance
}

type instancesProvider interface {
	DescribeInstances(ctx context.Context) ([]*ec2.Ec2Instance, error)
	DescribeVolumes(ctx context.Context, instances []*ec2.Ec2Instance) ([]*ec2.Volume, error)
}

func NewVulnerabilityFetcher(log *clog.Logger, provider instancesProvider) VulnerabilityFetcher {
	log.Debug("VulnerabilityFetcher: New")
	ch := make(chan *ec2.Ec2Instance)
	return VulnerabilityFetcher{
		log:      log,
		ch:       ch,
		provider: provider,
	}
}

func (f VulnerabilityFetcher) FetchInstances(ctx context.Context) error {
	defer close(f.ch)
	f.log.Info("Starting VulnerabilityFetcher.FetchInstances")
	ins, err := f.provider.DescribeInstances(ctx)
	if err != nil {
		f.log.Errorf("VulnerabilityFetcher.FetchInstances DescribeInstances failed: %v", err)
		return err
	}
	f.log.Infof("VulnerabilityFetcher.FetchInstances found %d results", len(ins))

	err = f.attachRootVolumes(ctx, ins)
	if err != nil {
		f.log.Errorf("VulnerabilityFetcher.FetchInstances attachRootVolumes failed: %v", err)
	} else {
		f.sortByRootVolumeSize(ins)
	}

	for _, in := range ins {
		select {
		case <-ctx.Done():
			f.log.Info("VulnerabilityFetcher.FetchInstances context canceled")
			return nil
		case f.ch <- in:
		}
	}
	f.log.Info("VulnerabilityFetcher.FetchInstances finished")
	return nil
}

func (f VulnerabilityFetcher) attachRootVolumes(ctx context.Context, instances []*ec2.Ec2Instance) error {
	volumes, err := f.provider.DescribeVolumes(ctx, instances)
	if err != nil {
		return err
	}

	volumesMapping := make(map[string][]*ec2.Volume)
	for _, vol := range volumes {
		volumesMapping[vol.InstanceId] = append(volumesMapping[vol.InstanceId], vol)
	}

	for _, ins := range instances {
		instanceVolumes := volumesMapping[*ins.InstanceId]
		for _, vol := range instanceVolumes {
			if vol.Device == *ins.RootDeviceName {
				ins.RootVolume = vol
				break
			}
		}
	}

	return nil
}

func (f VulnerabilityFetcher) sortByRootVolumeSize(instances []*ec2.Ec2Instance) {
	sort.Slice(instances, func(i, j int) bool {
		if instances[i].RootVolume == nil {
			return false
		}

		if instances[j].RootVolume == nil {
			return true
		}
		return instances[i].RootVolume.Size < instances[j].RootVolume.Size
	})
}

func (f VulnerabilityFetcher) GetChan() chan *ec2.Ec2Instance {
	return f.ch
}