Rack
VCR provides a rack middleware that uses a cassette for the duration of a request. Simply provide VCR::Middleware::Rack
with a block that sets the cassette name and options. You can set these based on the rack env if your block accepts two arguments.
This is useful in a couple different ways:
In a rails app, you could use this to log all HTTP API calls made by
the rails app (using the
:all
record mode). Of course, this will onlyrecord HTTP API calls made in the request-response cycle--API calls that
are offloaded to a background job will not be logged.
This can be used as middleware in a simple rack HTTP proxy, to record
and replay the proxied requests.
Background ()
Given a file named "remote_server.rb" with:
request_count = 0
$server = start_sinatra_app do
get('/:path') { "Hello #{params[:path]} #{request_count += 1}" }
end
And a file named "client.rb" with:
require 'remote_server'
require 'proxy_server'
require 'cgi'
url = URI.parse("http://localhost:#{$proxy.port}?url=#{CGI.escape("http://localhost:#{$server.port}/foo")}")
puts "Response 1: #{Net::HTTP.get_response(url).body}"
puts "Response 2: #{Net::HTTP.get_response(url).body}"
And the directory "cassettes" does not exist.
Use VCR rack middleware to record HTTP responses for a simple rack proxy app
Given a file named "proxy_server.rb" with:
require 'vcr'
$proxy = start_sinatra_app do
use VCR::Middleware::Rack do |cassette|
cassette.name 'proxied'
cassette.options :record => :new_episodes
end
get('/') { Net::HTTP.get_response(URI.parse(params[:url])).body }
end
VCR.configure do |c|
c.cassette_library_dir = 'cassettes'
c.hook_into :webmock
c.allow_http_connections_when_no_cassette = true
end
When I run ruby client.rb
Then the output should contain:
Response 1: Hello foo 1
Response 2: Hello foo 1
And the file "cassettes/proxied.yml" should contain "Hello foo 1".
Set cassette name based on rack request env
Given a file named "proxy_server.rb" with:
require 'vcr'
$proxy = start_sinatra_app do
use VCR::Middleware::Rack do |cassette, env|
cassette.name env['SERVER_NAME']
end
get('/') { Net::HTTP.get_response(URI.parse(params[:url])).body }
end
VCR.configure do |c|
c.cassette_library_dir = 'cassettes'
c.hook_into :webmock
c.allow_http_connections_when_no_cassette = true
end
When I run ruby client.rb
Then the output should contain:
Response 1: Hello foo 1
Response 2: Hello foo 1
And the file "cassettes/localhost.yml" should contain "Hello foo 1".
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