Health APIでメンテナンス必要な件数をMackerelで可視化

package main

import (
    "log"
    "os"
    "time"

    "github.com/aws/aws-lambda-go/lambda"
    "github.com/aws/aws-sdk-go/aws"
    "github.com/aws/aws-sdk-go/aws/credentials/stscreds"
    "github.com/aws/aws-sdk-go/aws/session"
    "github.com/aws/aws-sdk-go/service/health"
    "github.com/aws/aws-sdk-go/service/sts"
    mackerel "github.com/mackerelio/mackerel-client-go"
)

var (
    client  = mackerel.NewClient(os.Getenv("APIKEY"))
    nowTime = time.Now()
)

// Request is argument specified at call
type Request struct {
    TargetList []TargetAccount `json:"TargetList"`
}

// TargetAccount is target account
type TargetAccount struct {
    Service string `json:"Service"`
    Name    string `json:"Name"`
    Role    string `json:"Role"`
}

func handler(req Request) (string, error) {

    sess := session.Must(session.NewSession())
    assumeRoler := sts.New(sess)

    eventParam := &health.DescribeEventsInput{
        Filter: &health.EventFilter{
            EventStatusCodes: []*string{
                aws.String(health.EventStatusCodeOpen),
                aws.String(health.EventStatusCodeUpcoming),
            },
            EventTypeCategories: []*string{
                aws.String(health.EventTypeCategoryScheduledChange),
            },
        },
    }

    for _, target := range req.TargetList {
        creds := stscreds.NewCredentialsWithClient(assumeRoler, target.Role)
        svc := health.New(sess, aws.NewConfig().WithRegion("us-east-1").WithCredentials(creds))

        var arns []*string
        err := svc.DescribeEventsPages(eventParam, func(resp *health.DescribeEventsOutput, lastPage bool) bool {
            for _, event := range resp.Events {
                arns = append(arns, event.Arn)
            }
            return true
        })

        if err != nil {
            log.Println(err.Error())
            continue
        }

        entityParam := &health.DescribeAffectedEntitiesInput{
            Filter: &health.EntityFilter{
                EventArns: arns,
            },
        }

        var entities []*health.AffectedEntity
        err = svc.DescribeAffectedEntitiesPages(entityParam, func(resp *health.DescribeAffectedEntitiesOutput, lastPage bool) bool {
            entities = append(entities, resp.Entities...)
            return true
        })

        if err != nil {
            log.Println(err.Error())
            continue
        }

        entities = removeUnknown(entities)

        err = client.PostServiceMetricValues(target.Service, []*mackerel.MetricValue{
            &mackerel.MetricValue{
                Name:  "monitor-maintenance." + target.Name,
                Time:  nowTime.Unix(),
                Value: len(entities),
            },
        })
        if err != nil {
            log.Println(err.Error())
            continue
        }
    }
    return "ok", nil
}

func removeUnknown(e []*health.AffectedEntity) []*health.AffectedEntity {
    result := []*health.AffectedEntity{}
    for _, v := range e {
        if *v.EntityValue == health.EntityStatusCodeUnknown {
            continue
        }
        result = append(result, v)
    }
    return result
}

func main() {
    lambda.Start(handler)
}