Module: S3Sign::Helper

Defined in:
lib/s3_sign/helper.rb

Overview

The S3Sign::Helper module provides two methods for generating S3 signed URLs with different caching strategies, designed to be included in Rails controllers.

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.included(base) ⇒ Object 



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# File 'lib/s3_sign/helper.rb', line 9

def self.included(base)
  if base.respond_to?(:helper_method)
    base.helper_method :stable_s3_signed_url
    base.helper_method :s3_signed_url_for_key
  end

  return unless base.respond_to?(:hide_action)

  base.hide_action :stable_s3_signed_url
  base.hide_action :s3_signed_url_for_key
end

Instance Method Details

#s3_signed_url_for_key(key, options = {}) ⇒ Object

A pure “time from now” signed s3 asset url. Good for non-visual elements like attachments, and not thumbnails, that don’t have the same caching concerns



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# File 'lib/s3_sign/helper.rb', line 23

def s3_signed_url_for_key(key, options = {})
  options[:expires] ||= 86_400
  S3Sign.url key, options
end

#stable_s3_signed_url(url, options = {}) ⇒ Object

Uses a far-future date so that the expires and signature on the url doesn’t change for every request. This lets us still protect assets but the browser can cache them because the url isn’t constantly changing.

Use for assets we want browser cached that don’t need higher level protection, such as thumbnails. Other more central assets like downloads for a course or videos should have short expiration because they generally don’t benefit as much from caching and need better time-based protection.

If a reference_time is given, that will use the time given but in the far future stable year. This is useful to cache-bust the url from an updated_at timestamp where some browsers/proxies may try to use the cached asset even though it was updated.



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# File 'lib/s3_sign/helper.rb', line 43

def stable_s3_signed_url(url, options = {})
  @stable_s3_expire_at ||= Time.parse("2036-1-1 00:00:00 UTC")

  if (reference_time = options.delete(:expires))
    # The time given but in the year 2036
    year       = @stable_s3_expire_at.year
    expires_at = Time.parse(reference_time.utc.strftime("#{year}-%m-%d %T UTC"))
  else
    expires_at = @stable_s3_expire_at
  end

  s3_signed_url_for_key(url, expires: expires_at)
end