Hack to make the Ruby gem aws-sdk-s3 work with Backblaze B2

storage_client.rb

module Vidjo
  # Factory for Aws::S3::Client so we only have to configure it in one place
  module StorageClient
    def self.new_s3_client
      # The B2 client doesn't work with stubbing for some reason, whatever
      stub_responses = ENV.fetch('S3_CLIENT_STUB_RESPONSES', nil) == 'yes'
      if stub_responses
        Aws::S3::Client.new(
          access_key_id: ENV.fetch('B2_KEY_ID'),
          secret_access_key: ENV.fetch('B2_APP_KEY'),
          endpoint: ENV.fetch('B2_ENDPOINT'),
          region: ENV.fetch('B2_REGION'),
          force_path_style: true,
          stub_responses: true
        )
      else
        B2S3Client.new(
          access_key_id: ENV.fetch('B2_KEY_ID'),
          secret_access_key: ENV.fetch('B2_APP_KEY'),
          endpoint: ENV.fetch('B2_ENDPOINT'),
          region: ENV.fetch('B2_REGION'),
          force_path_style: true
        )
      end
    end
  end

  # Subclass that strips checksums because B2 isn't compatible with them
  class B2S3Client < Aws::S3::Client
    # Plugin to strip checksum headers from requests
    class StripChecksumHeaders < Seahorse::Client::Plugin
      def add_handlers(handlers, _config)
        handlers.add(Handler, step: :build, priority: 0)
      end

      # Deletes all checksum headers from requests
      class Handler < Seahorse::Client::Handler
        def call(context)
          headers = context.http_request.headers
          headers.keys.grep(/^x-amz(-sdk)?-checksum-/i).each do |key|
            headers.delete(key)
          end
          @handler.call(context)
        end
      end
    end

    add_plugin(StripChecksumHeaders)
    define_singleton_method(:api) { Aws::S3::Client.api }
  end
end