94 lines
3.4 KiB
Ruby
94 lines
3.4 KiB
Ruby
# frozen_string_literal: true
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require 'faraday'
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require 'roda/proxy/version'
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# :nodoc:
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class Roda
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# :nodoc:
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module RodaPlugins
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# Roda plugin for simple API proxying
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module Proxy
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# Respond to the configure method to set the destination when proxying
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# Expects the following options:
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# [to] Required. The scheme and host of the proxy. Should not end with a slash.
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# [path] Optional. The path to append to the above for proxying.
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# Should begin with a +/+. Defaults to +/+.
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# Example:
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# plugin :proxy, to: 'https://foo.bar', path: '/my/api'
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def self.configure(app, opts = {})
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app.opts[:proxy_to] = opts.fetch(:to, nil)
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app.opts[:proxy_path] = opts.fetch(:path, '/')
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raise 'Proxy host not set, use "plugin :proxy, to: http://example.com"' unless app.opts[:proxy_to]
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end
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# :nodoc:
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module RequestMethods
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# Proxies the request, forwarding all headers except +Host+ which is
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# rewritten to be the destination host. The response headers, body and
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# status are returned to the client.
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def proxy
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method = Faraday.method(env['REQUEST_METHOD'].downcase.to_sym)
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f_response = method.call(_proxy_url) { |req| _proxy_request(req) }
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_respond(f_response)
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end
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# Conditionally proxies when +condition+ is true and with selective probability.
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# For instance, to proxy 50% of the time:
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# r.proxy_when(probability: 0.5)
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# Condition can be a truthy value or a block / lambda, in which case
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# the result from the +#call+ is expected to be truthy.
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# r.proxy_when( r.env['HTTP_PROXY_ME'] == 'true' )
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# The two parameters can be combined, the probability is evaluated first.
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# r.proxy_when( r.env['HTTP_PROXY_ME'] == 'true', probability: 0.8 )
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# If and only if this method choses not to proxy is the block evaluated.
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# The block is then expected to return a meaningful response to Roda.
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def proxy_when(condition = true, probability: 1.0)
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shall_proxy = Random.rand(0.0..1.0) <= probability
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if shall_proxy && ( condition.respond_to?(:call) ? condition.call : condition )
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yield(self)
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else
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proxy
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end
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end
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private
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def _proxy_url
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@_proxy_url ||= URI(roda_class.opts[:proxy_to])
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.then { |uri| uri.path = roda_class.opts[:proxy_path]; uri }
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.then { |uri| uri.query = env['QUERY_STRING']; uri }
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end
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def _proxy_headers
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env
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.select { |k, _v| k.start_with? 'HTTP_' }
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.reject { |k, _v| k == 'HTTP_HOST' }
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.transform_keys do |k|
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k.sub(/^HTTP_/, '')
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.split('_')
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.map(&:capitalize)
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.join('-')
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end.merge({ 'Host' => "#{_proxy_url.host}:#{_proxy_url.port}" })
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end
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def _proxy_request(req)
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req.headers = _proxy_headers
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end
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def _respond(proxied_response)
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response.status = proxied_response.status
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proxied_response.headers.each { |k, v| response[k] = v }
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response.write(proxied_response.body)
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end
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end
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end
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register_plugin :proxy, Proxy
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end
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end
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