Below are common questions regarding the use of Amazon S3 in the AWS CLI.
The AWS CLI will perform checksum validation for uploading files in specific scenarios.
The AWS CLI will calculate and auto-populate the Content-MD5
header for
both standard and multipart uploads. If the checksum that S3 calculates does
not match the Content-MD5
provided, S3 will not store the object and
instead will return an error message back the AWS CLI. The AWS CLI will retry
this error up to 5 times before giving up. On the case that any files fail to
transfer successfully to S3, the AWS CLI will exit with a non zero RC.
See aws help return-codes
for more information.
If the upload request is signed with Signature Version 4, then the AWS CLI uses the
x-amz-content-sha256
header as a checksum instead of Content-MD5
.
The AWS CLI will use Signature Version 4 for S3 in several cases:
eu-central-1
and ap-northeast-2
.signature_version = s3v4
in your
~/.aws/config
file.Note that the AWS CLI will add a Content-MD5
header for both
the high level aws s3
commands that perform uploads
(aws s3 cp
, aws s3 sync
) as well as the low level s3api
commands including aws s3api put-object
and aws s3api upload-part
.
If you want to verify the integrity of an object during upload, see How can I check the integrity of an object uploaded to Amazon S3? in the AWS Knowledge Center.