How do I upload a gzip object to s3? - php

Question

I am creating a gzip string and uploading it as an object to s3. However when I download the same file from s3 and decompress it locally with gunzip I get this error: gunzip: 111.gz: not in gzip format When I look at the mime_content_type returned in the file downloaded from s3 it is set as: application/zlib
Here is the code I am running to generate the gzip file and push it to s3:
for($i=0;$i<=100;$i++) {
$content .= $i . "\n";
}
$result = $this->s3->putObject(array(
'Bucket' => 'my-bucket-name',
'Key' => '111.gz',
'Body' => gzcompress($content),
'ACL' => 'authenticated-read',
'Metadata' => [
'ContentType' => 'text/plain',
'ContentEncoding' => 'gzip'
]
));
The strange thing is that if I view the gzip content locally before I send it to s3 I am able to decompress it and see the original string. So I must be uploading the file incorrectly, any thoughts?

Answer 1

According to http://docs.aws.amazon.com/aws-sdk-php/v3/api/api-s3-2006-03-01.html#putobject the ContentType and ContentEncoding parameters belong on top level, and not under Metadata. So your call should look like:
$result = $this->s3->putObject(array(
'Bucket' => 'my-bucket-name',
'Key' => '111.gz',
'Body' => gzencode($content),
'ACL' => 'authenticated-read',
'ContentType' => 'text/plain',
'ContentEncoding' => 'gzip'
));
Also it's possible that by setting ContentType to text/plain your file might be truncated whenever a null-byte occurs. I would try with'application/gzip' if you still have problems unzipping the file.

Answer 2

I had a very similar issue, and the only way to make it work for our file was with a code like this (slightly changed according to your example):
$this->s3->putObject(array(
'Bucket' => 'my-bucket-name',
'Key' => '111.gz',
'Body' => gzcompress($content, 9, ZLIB_ENCODING_GZIP),
'ACL' => 'public-read',
'ContentType' => 'text/javascript',
'ContentEncoding' => 'gzip'
));
The relevant part being gzcompress($content, 9, ZLIB_ENCODING_GZIP), as AWS S3 wouldn't recognize the file nor serve it in the right format without the last ZLIB_ENCODING_GZIP parameter.