Change metadata on existing S3 files

change_s3_metadata.rb

# Using v1 of Ruby aws-sdk as currently v2 seems not able to do this (broken?).
require 'aws-sdk-v1'

key = YOUR_AWS_KEY
secret = YOUR_AWS_SECRET
region = YOUR_AWS_REGION

AWS.config(access_key_id: key, secret_access_key: secret, region: region)
s3 = AWS::S3.new
bucket = s3.buckets[bucket_name]
bucket.objects.with_prefix('images/').each do |obj|
  puts obj.key
  # Add  metadata: {} to next line for more metadata.
  obj.copy_from(obj.key, content_type: obj.content_type, cache_control: 'max-age=1576800000',  acl: :public_read)
end

change_s3_metadata_sdk2.rb

# Using aws-sdk version 2.
# NOTE: This currently does NOT seem to work.

require 'aws-sdk'
credentials = Aws::Credentials.new(aws_key, aws_secret)
# s3 = Aws::S3::Client.new(credentials: credentials, region: aws_region)
# s3.list_objects(bucket: bucket_name, prefix: "images/").each do |response|
#   puts response.contents.first
#   puts response.contents.map(&:key)
# end

# operation_names
s3resource = Aws::S3::Resource.new(credentials: credentials, region: Rails.configuration.aws_region)
bucket = s3resource.bucket(bucket_name)
# obj = bucket.objects.first

bucket.objects.each do |obj|
  puts "#{obj.key} => #{obj.etag}"
  # obj.copy_from(obj.key) # FIXME: Using aws-sdk v2.0.27 this currently does not work :S
end

Yeah so #copy_from either #copy_to doesn't work/exists, although documentations mentions them. here's what I did (down&up-loading each file):

s3o = bucket.object key
IO.copy_stream s3o.get.body, tmp_file
s3o.upload_file tmp_file, content_type: 'image/jpeg'

#copy_from and #copy_to work fine; see my Stack Overflow answer: http://stackoverflow.com/a/39156978