Uso de HeadBucket con un SDK de AWS o la CLI

###############################################################################
# function bucket_exists
#
# This function checks to see if the specified bucket already exists.
#
# Parameters:
#       $1 - The name of the bucket to check.
#
# Returns:
#       0 - If the bucket already exists.
#       1 - If the bucket doesn't exist.
###############################################################################
function bucket_exists() {
  local bucket_name
  bucket_name=$1

  # Check whether the bucket already exists.
  # We suppress all output - we're interested only in the return code.

  if aws s3api head-bucket \
    --bucket "$bucket_name" \
    >/dev/null 2>&1; then
    return 0 # 0 in Bash script means true.
  else
    return 1 # 1 in Bash script means false.
  fi
}

El siguiente comando verifica el acceso a un bucket denominado amzn-s3-demo-bucket:

aws s3api head-bucket --bucket amzn-s3-demo-bucket

Si el bucket existe y tiene acceso a él, no se muestra ningún resultado. De lo contrario, se mostrará un mensaje de error. Por ejemplo:

A client error (404) occurred when calling the HeadBucket operation: Not Found

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"log"
	"os"
	"time"

	"github.com/aws/aws-sdk-go-v2/aws"
	"github.com/aws/aws-sdk-go-v2/feature/s3/manager"
	"github.com/aws/aws-sdk-go-v2/service/s3"
	"github.com/aws/aws-sdk-go-v2/service/s3/types"
	"github.com/aws/smithy-go"
)

// BucketBasics encapsulates the Amazon Simple Storage Service (Amazon S3) actions
// used in the examples.
// It contains S3Client, an Amazon S3 service client that is used to perform bucket
// and object actions.
type BucketBasics struct {
	S3Client *s3.Client
}



// BucketExists checks whether a bucket exists in the current account.
func (basics BucketBasics) BucketExists(ctx context.Context, bucketName string) (bool, error) {
	_, err := basics.S3Client.HeadBucket(ctx, &s3.HeadBucketInput{
		Bucket: aws.String(bucketName),
	})
	exists := true
	if err != nil {
		var apiError smithy.APIError
		if errors.As(err, &apiError) {
			switch apiError.(type) {
			case *types.NotFound:
				log.Printf("Bucket %v is available.\n", bucketName)
				exists = false
				err = nil
			default:
				log.Printf("Either you don't have access to bucket %v or another error occurred. "+
					"Here's what happened: %v\n", bucketName, err)
			}
		}
	} else {
		log.Printf("Bucket %v exists and you already own it.", bucketName)
	}

	return exists, err
}

Ejemplo 1: Este comando devuelve el resultado con el código de estado HTTP 200 OK para el bucket existente cuando el usuario tiene permiso para acceder a él. El parámetro BucketArn solo se admite en los buckets de directorio de S3.

Get-S3HeadBucket -BucketName amzn-s3-demo-bucket

Salida:

AccessPointAlias   : False
BucketArn          :
BucketLocationName : 
BucketLocationType : 
BucketRegion       : us-east-2
ResponseMetadata   : Amazon.Runtime.ResponseMetadata
ContentLength      : 0
HttpStatusCode     : OK

Ejemplo 2: Este comando produce un error con el código de estado HTTP NotFound cuando el bucket no existe.

Get-S3HeadBucket -BucketName amzn-s3-non-existing-bucket

Salida:

Get-S3HeadBucket: Error making request with Error Code NotFound and Http Status Code NotFound. No further error information was returned by the service.

Ejemplo 3: Este comando produce un error con el código de estado HTTP Forbidden para un bucket existente cuando el usuario no tiene permiso para acceder a él.

Get-S3HeadBucket -BucketName amzn-s3-no-access-bucket

Salida:

Get-S3HeadBucket: Error making request with Error Code Forbidden and Http Status Code Forbidden. No further error information was returned by the service.

class BucketWrapper:
    """Encapsulates S3 bucket actions."""

    def __init__(self, bucket):
        """
        :param bucket: A Boto3 Bucket resource. This is a high-level resource in Boto3
                       that wraps bucket actions in a class-like structure.
        """
        self.bucket = bucket
        self.name = bucket.name


    def exists(self):
        """
        Determine whether the bucket exists and you have access to it.

        :return: True when the bucket exists; otherwise, False.
        """
        try:
            self.bucket.meta.client.head_bucket(Bucket=self.bucket.name)
            logger.info("Bucket %s exists.", self.bucket.name)
            exists = True
        except ClientError:
            logger.warning(
                "Bucket %s doesn't exist or you don't have access to it.",
                self.bucket.name,
            )
            exists = False
        return exists