AWSのLambdaでS3にアップロードされたファイルをhookで受け取ってファイルの中身を取得する(apex利用)

参照URL

s3: https://docs.aws.amazon.com/ja_jp/lambda/latest/dg/with-s3.html
apex: https://github.com/apex/go-apex

コード(ほぼapexに記載されているのでその写経)

config.go

// Ref: https://github.com/apex/go-apex/blob/master/s3/s3.go

// Event represents a S3 event with one or more records.
type Event struct {
    Records []*Record `json:"Records"`
}

// Record represents a single S3 record.
type Record struct {
    EventVersion string    `json:"eventVersion"`
    EventSource  string    `json:"eventSource"`
    AWSRegion    string    `json:"awsRegion"`
    EventTime    time.Time `json:"eventTime"`
    EventName    string    `json:"eventName"`
    UserIdentity struct {
        PrincipalID string `json:"principalId"`
    } `json:"userIdentity"`
    RequestParameters struct {
        SourceIPAddress string `json:"sourceIPAddress"`
    } `json:"requestParameters"`
    S3 struct {
        SchemaVersion   string  `json:"s3SchemaVersion"`
        ConfigurationID string  `json:"configurationId"`
        Bucket          *Bucket `json:"bucket"`
        Object          *Object `json:"object"`
    }
}

s3.go

// ReadS3Object is Load json file uploaded
func ReadS3Object(event Event) []byte {
    bucket := event.Records[0].S3.Bucket.Name
    object := event.Records[0].S3.Object.Key

    svc := s3.New(session.New())

    params := &s3.GetObjectInput{
        Bucket: aws.String(bucket),
        Key:    aws.String(object),
    }

    resp, err := svc.GetObject(params)
    if err != nil {
        log.Fatal(err)
    }

    b, _ := ioutil.ReadAll(resp.Body)

    return b
}

main.go

package main

import (
    "encoding/json"
    "log"

    apex "github.com/apex/go-apex"
)

func main() {

    apex.HandleFunc(func(data json.RawMessage, ctx *apex.Context) (interface{}, error) {

        var e Event

        // Reccieved "data" convert the "e" object which is build by Event structure
        err := json.Unmarshal(data, &e)
        if err != nil {
            log.Fatal(err)
        }

        d := ReadS3Object(e)

        log.Println(string(d))

        return nil, nil
    })
}