Asset Host Selection 
A basic pattern for ActionController to select between multiple CDNs.
Supports:
- Multiple asset providers
- Disabling asset providers
- CDN killswitch environment variable to disable all CDNs
Usage
The host application is required to configure the desired asset providers, and handle the selection logic with an object that responds to #select and returns a provider:
# providers = {
# :cloudfront => {
# :subdomain => "example",
# :domain => "cloudfront.net",
# :cdn => true
# },
# :edgecast => {
# :subdomain => "assets",
# :domain => example.com,
# :cdn => true
# },
# :internal => {
# :subdomain => "assets2",
# :domain => example.com,
# :cdn => false
# }
# }
#
#
# provider_pool = ProviderPool.new(providers)
# config.asset_host = AssetHostSelection::AssetHostname.new(provider_pool)
class ProviderPool
attr_reader :providers
def initialize(provider_attributes)
@providers = AssetHostSelection::AssetProvider.build_all(provider_attributes)
end
def select(request)
account = request.env["account"]
provider = account.asset_provider
if provider.try(:enabled?)
provider
else
providers[:internal]
end
end
endCopyright and license
Copyright 2013 Zendesk Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.