GoでS3の署名付きURLを作成

意外と見つけるまで時間がかかってしまったのでメモです。

参考

公式ドキュメントです。

前提

• AWSの認証情報が環境変数として登録されている

export AWS_ACCESS_KEY_ID=yyyyy
export AWS_REGION=ap-northeast-1
export AWS_SECRET_ACCESS_KEY=xxxxxx

コード

main.go

// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX - License - Identifier: Apache - 2.0
package main

import (
    "context"
    "flag"
    "fmt"

    v4 "github.com/aws/aws-sdk-go-v2/aws/signer/v4"
    "github.com/aws/aws-sdk-go-v2/config"
    "github.com/aws/aws-sdk-go-v2/service/s3"
)

// S3PresignGetObjectAPI defines the interface for the PresignGetObject function.
// We use this interface to test the function using a mocked service.
type S3PresignGetObjectAPI interface {
    PresignGetObject(
        ctx context.Context,
        params *s3.GetObjectInput,
        optFns ...func(*s3.PresignOptions)) (*v4.PresignedHTTPRequest, error)
}

// GetPresignedURL retrieves a presigned URL for an Amazon S3 bucket object.
// Inputs:
//     c is the context of the method call, which includes the AWS Region.
//     api is the interface that defines the method call.
//     input defines the input arguments to the service call.
// Output:
//     If successful, the presigned URL for the object and nil.
//     Otherwise, nil and an error from the call to PresignGetObject.
func GetPresignedURL(c context.Context, api S3PresignGetObjectAPI, input *s3.GetObjectInput) (*v4.PresignedHTTPRequest, error) {
    return api.PresignGetObject(c, input)
}

func main() {
    bucket := flag.String("b", "", "The bucket")
    key := flag.String("k", "", "The object key")

    flag.Parse()

    if *bucket == "" || *key == "" {
        fmt.Println("You must supply a bucket name (-b BUCKET) and object key (-k KEY)")
        return
    }

    cfg, err := config.LoadDefaultConfig(context.TODO())
    if err != nil {
        panic("configuration error, " + err.Error())
    }

    client := s3.NewFromConfig(cfg)

    input := &s3.GetObjectInput{
        Bucket: bucket,
        Key:    key,
    }

    psClient := s3.NewPresignClient(client)

    resp, err := GetPresignedURL(context.TODO(), psClient, input)
    if err != nil {
        fmt.Println("Got an error retrieving pre-signed object:")
        fmt.Println(err)
        return
    }

    fmt.Println("The URL: ")
    fmt.Println(resp.URL)
}

コマンド

go run presigned/main.go -b my-bucket -k photo.png
The URL:
https://xxxx.s3.ap-northeast-1.amazonaws.com/photo.png?X-Amz-Algorithm=......