How do I update a batch of S3 objects' metadata using ruby?

Question

I need to change some metadata (Content-Type) on hundreds or thousands of objects on S3. What's a good way to do this with ruby? As far as I can tell there is no way to save only metadata with fog.io, the entire object must be re-saved. Seems like using the official sdk library would require me rolling a wrapper environment just for this one task.

Answer 1

Using the sdk to change the content type will result in x-amz-meta- prefix. My solution was to use ruby + aws cli. This will directly write to the content-type instead of x-amz-meta-content-type.

ids_to_copy = all_object_ids
ids_to_copy.each do |id|
    object_key = "#{id}.pdf"
    command = "aws s3 cp s3://{bucket-name}/#{object_key} s3://{bucket-name}/#{object_key} --no-guess-mime-type --content-type='application/pdf' --metadata-directive='REPLACE'"
    system(command)
end

Answer 2

after some search this seems to work for me

obj.copy_to(obj, :metadata_directive=>"REPLACE", :acl=>"public-read",:content_type=>"text/plain")