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aws-sdk-go

You must generate an Access Key before getting started. All examples will utilize access_key_id and access_key_secret variables which represent the Access Key ID and Secret Access Key values you generated.

This example uses version 2 of the aws-sdk-go ↗ package. You must pass in the R2 configuration credentials when instantiating your S3 service client:

Client version 1.73.0 introduced a modification to the default checksum behavior from the client that is currently incompatible with R2 APIs.

To mitigate, users can use 1.72.3 or add the following to their config:

config.WithRequestChecksumCalculation(0)
config.WithResponseChecksumValidation(0)

package main

import (
  "context"
  "encoding/json"
  "fmt"
  "github.com/aws/aws-sdk-go-v2/aws"
  "github.com/aws/aws-sdk-go-v2/config"
  "github.com/aws/aws-sdk-go-v2/credentials"
  "github.com/aws/aws-sdk-go-v2/service/s3"
  "log"
)

func main() {
  var bucketName = "sdk-example"
  var accountId = "<accountid>"
  var accessKeyId = "<access_key_id>"
  var accessKeySecret = "<access_key_secret>"

  cfg, err := config.LoadDefaultConfig(context.TODO(),
    config.WithCredentialsProvider(credentials.NewStaticCredentialsProvider(accessKeyId, accessKeySecret, "")),
    config.WithRegion("auto"),
  )
  if err != nil {
    log.Fatal(err)
  }

  client := s3.NewFromConfig(cfg, func(o *s3.Options) {
      o.BaseEndpoint = aws.String(fmt.Sprintf("https://%s.r2.cloudflarestorage.com", accountId))
  })

  listObjectsOutput, err := client.ListObjectsV2(context.TODO(), &s3.ListObjectsV2Input{
    Bucket: &bucketName,
  })
  if err != nil {
    log.Fatal(err)
  }

  for _, object := range listObjectsOutput.Contents {
    obj, _ := json.MarshalIndent(object, "", "\t")
    fmt.Println(string(obj))
  }

  //  {
  //    "ChecksumAlgorithm": null,
  //    "ETag": "\"eb2b891dc67b81755d2b726d9110af16\"",
  //    "Key": "ferriswasm.png",
  //    "LastModified": "2022-05-18T17:20:21.67Z",
  //    "Owner": null,
  //    "Size": 87671,
  //    "StorageClass": "STANDARD"
  //  }

  listBucketsOutput, err := client.ListBuckets(context.TODO(), &s3.ListBucketsInput{})
  if err != nil {
    log.Fatal(err)
  }

  for _, object := range listBucketsOutput.Buckets {
    obj, _ := json.MarshalIndent(object, "", "\t")
    fmt.Println(string(obj))
  }

  // {
  //     "CreationDate": "2022-05-18T17:19:59.645Z",
  //     "Name": "sdk-example"
  // }
}

Generate presigned URLs

You can also generate presigned links that can be used to temporarily share public write access to a bucket.

presignClient := s3.NewPresignClient(client)

  presignResult, err := presignClient.PresignPutObject(context.TODO(), &s3.PutObjectInput{
    Bucket: aws.String(bucketName),
    Key:    aws.String("example.txt"),
  })

  if err != nil {
    panic("Couldn't get presigned URL for PutObject")
  }

  fmt.Printf("Presigned URL For object: %s\n", presignResult.URL)

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