Add support for additional metadata headers.

[harshavardhana]

This is implemented since we have already implemented
PutObjectWithMetadata() in minio-go. So following the
logic here.

This adds support to be able to specify x-amz-storage-class etc.

Fixes #482

[hashbackup]

Took a brief look at this. At line 585, don't you mean "if not content_type"? And since there is already a default in the arg list, the only way this could happen is if fput is called with an explicit content_type=None or null string, which seems a little strange.

[harshavardhana]

Took a brief look at this. At line 585, don't you mean "if not content_type"? And since there is already a default in the arg list, the only way this could happen is if fput is called with an explicit content_type=None or null string, which seems a little strange.

Oh yes good catch @hashbackup

[harshavardhana]

Oh yes good catch @hashbackup

Can you validate @hashbackup this new API change?

[hashbackup]

Looks okay to me, without running it. I'm a dumbass and can't figure out how to get a copy of the changes, sorry. Duh.

The keyword issue (case sensitive) is still a problem I think. It's not a big deal for minio devs to follow a case convention, but will likely trip up others when they start adding their own keywords / metadata. See the change I made to signer.py

Another way would be a case-insensitive dict. Not sure you want to go to the trouble, but I believe it is the most correct solution since http headers actually are case-insensitive.

[harshavardhana]

Another way would be a case-insensitive dict. Not sure you want to go to the trouble, but I believe it is the most correct solution since http headers actually are case-insensitive.

HTTP headers are case insensitive so it doesn't matter what they are really. So you don't have to worry about it on client.

[hashbackup]

True, it doesn't matter. But if you do this:

headers['A'] = 'xyz'
headers['a'] = 'abc'

and pass that as metadata, the minio signing procedure fails because it does a header.title() thing. That fails for the lowercase header. When I initially implemented headers, I ran into this because I used 'x-aws-storage-class' as the header name. Try it.

Update: this is a bad test case that actually works. Just use the lowercase header and it fails.

[harshavardhana]

headers['A'] = 'xyz'
headers['a'] = 'abc'

Ah i see what you mean let me see how to avoid a scenario.

[harshavardhana]

and pass that as metadata, the minio signing procedure fails because it does a header.title() thing. That fails for the lowercase header. When I initially implemented headers, I ran into this because I used 'x-aws-storage-class' as the header name. Try it.

Fixed it

---------START-HTTP---------
PUT /d3259f44-3cc3-49f0-aa4d-28dcaebc27f4-f HTTP/1.1
X-Amz-Content-Sha256: UNSIGNED-PAYLOAD
Content-Length: 136
X-Amz-Storage-Class: STANDARD_IA
Content-Md5: GdUHuO2I7Ong4SXepUs4Rw==
Host: minio-pytest.s3.amazonaws.com
X-Amz-Date: 20170224T203439Z
User-Agent: Minio (Linux; x86_64) minio-py/2.1.0
Authorization: AWS4-HMAC-SHA256 Credential=AKIAJY2EP7JTV2SUOH4Q/20170224/us-east-1/s3/aws4_request, SignedHeaders=content-length;content-md5;host;user-agent;x-amz-content-sha256;x-amz-date;x-amz-storage-class, Signature=bd1ca72b011e96078cb431c4d0b3d717718322d9e502f7ba0b5f8df6470ebdb4

HTTP/1.1 200
X-Amz-Id-2: Q+rs7cnD4pYbRpzPrTAiSsN7pFGR8gYDO3v+JyUXNFyI5btlCDWB9om6kzmKeUtSAYQ4TJimRZI=
X-Amz-Request-Id: 78CC40C83B527E89
Date: Fri, 24 Feb 2017 20:34:40 GMT
Etag: "19d507b8ed88ece9e0e125dea54b3847"
X-Amz-Storage-Class: STANDARD_IA
Content-Length: 0
Server: AmazonS3
---------END-HTTP---------

Works fine either way, picks one of the duplicated elements using a case insensitive dictionary helped.