aws s3 cp with --metadata-directive REPLACE not guessing correct Content-Type

[bersalazar]

Confirm by changing [ ] to [x] below to ensure that it's a bug:

• I've gone though the User Guide and the API reference
• I've searched for previous similar issues and didn't find any solution

Describe the bug
When using awscli v2 and copying a file using aws s3 cp with the --metadata-directive REPLACE parameter, Content-Type is not correctly guessed for files and are set to binary/octet-stream after upload.

This behavior is not present when running the same command from Ubuntu or when using awscli v1 from macOS.

SDK version number
aws-cli/2.1.35 Python/3.8.8 Darwin/19.6.0 exe/x86_64 prompt/off

Platform/OS/Hardware/Device
macOS 10.15.7 (Catalina)

To Reproduce (observed behavior)
aws s3 cp <bucket>/<file> <bucket>/<file> --metadata-directive REPLACE

Expected behavior
Content-type is correctly guessed by aws s3 cp, even if the source metadata is replaced.

Logs/output
debug-logs-from-aws-s3-cp.txt

Additional context
awscli makes use of Python's mimetypes module for guessing MIME types for files, which are usually installed in /etc/mime.types in Ubuntu, however, this is not the directory where the mime.types file is present for macOS. They are found in /etc/apache2/mime.types which the mimetypes module has listed as knownfiles for fetching MIME types. In spite of this, awscli doesn't seem to pick up them up.

Python 3.8.5 (default, Feb 16 2021, 11:12:50)
[Clang 12.0.0 (clang-1200.0.32.29)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import mimetypes
>>> mimetypes.knownfiles
['/etc/mime.types', '/etc/httpd/mime.types', '/etc/httpd/conf/mime.types', '/etc/apache/mime.types', '/etc/apache2/mime.types', '/usr/local/etc/httpd/conf/mime.types', '/usr/local/lib/netscape/mime.types', '/usr/local/etc/httpd/conf/mime.types', '/usr/local/etc/mime.types']

This issue is not present in awscli v1, where the --metadata-directive REPLACE parameter guesses correctly the Content-Types when copying.

[stobrien89]

Hi @bersalazar,

Thanks for pointing this out— I was able to reproduce. Marking as a bug for now.

[stobrien89]

Hi @bersalazar,

#6115 should take care of this— next V2 release will hopefully be next week. Please feel free to reach out if you're still having issues after that!

[stobrien89]

Hi @bersalazar,

After a review of the v1 behavior and the PR I mentioned in my last comment, it looks like we actually explicitly removed support for guessing mimetypes for copies in v2 now that we copy over metadata— it was only by accident that v1 supports injecting mimetypes. Even in the docs for v1 --no-guess-mimetype, it states that this is only supported for uploads.

Would you be able to clarify what your particular use case is for this? We may have a current set of parameters that could work and we're hesitant to add this 'mistake' back if there's not a strong reason for it. Thanks!

[bersalazar]

Hi @stobrien89

Thanks for the replies. The use case is indeed when copying files from bucket to bucket. The source and target buckets are the same in this case, the idea is to use aws cp to inject the --cache-control 'no-cache' header to a HTML file, after an aws s3 sync.

[stobrien89]

Hi @bersalazar,

I may be missing something here, but I did some testing with aws s3 sync s3://src-bucket s3://dest-bucket --cache-control no-cache and that appears to copy over the correct content-type, as well as the no-cache header. Have you tried this as well?

[bersalazar]

hey @stobrien89, aws sync probably works correctly. The issue is on aws cp. The workflow is as follows:

• aws sync from local to bucketA a big directory of static files
• aws cp from bucketA to bucketA to set --cache-control no-cache --metadata-directive REPLACE to one specific file

Content-Type is correctly set on sync, however on cp it doesn't carry over the correct Content-Type for that one file, it replaces with binary/octet-stream.

I understand --metadata-directive REPLACE would only set the values specified in the command's parameters, but maybe the ones that are NOT specified should be guessed, or copied? Trying to understand what the correct behavior should be here.

[stobrien89]

Hi @bersalazar,

My apologies— I almost forgot you were needing to copy a single file rather than an entire directory.

So the 'correct' behavior is actually found in v2 for reasons I mentioned before— if you compare debug logs between v1 and v2 for aws s3 cp s3://src-bucket s3://dest-bucket --cache-control 'no-cache' --metadata-directive REPLACE, v1 actually sends the content-type header as a part of the copy request. REPLACE, in theory, should only have the metadata values that were specified by the CLI command.

In this case, you may be better off not specifying --metadata-directive REPLACE in v2, as the correct content-type is retained during the copy, or manually specify --content-type as text/html if there are other metadata values that you need to replace.

To test, you can create a blank index.html file (or something to that effect), use cp to upload to your source bucket, call s3api head-object on the uploaded object, copy the file to the destination bucket using cp with cache-control and then call s3api head-object on the file in the destination bucket to display the content-type and cache-control metadata.

Hope this helps!

[bersalazar]

OK, thanks for the help and clarification @stobrien89, really appreciated!

[stobrien89]

Of course— Hope this works for you! Please feel free to reach out at any time if you have any additional questions.