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# frozen_string_literal: true
require "opentracing"
require "action_dispatch"
module Labkit
module Tracing
# RackMiddleware is a rack middleware component for
# instrumenting incoming http requests into a Rails/Rack
# server
class RackMiddleware
REQUEST_METHOD = "REQUEST_METHOD"
def initialize(app)
@app = app
end
def call(env)
method = env[REQUEST_METHOD]
context = TracingUtils.tracer.extract(OpenTracing::FORMAT_RACK, env)
tags = { "component" => "rack", "span.kind" => "server", "http.method" => method, "http.url" => self.class.build_sanitized_url_from_env(env) }
TracingUtils.with_tracing(operation_name: "http:#{method}", child_of: context, tags: tags) do |span|
@app.call(env).tap { |status_code, _headers, _body| span.set_tag("http.status_code", status_code) }
end
end
# Generate a sanitized (safe) request URL from the rack environment
def self.build_sanitized_url_from_env(env)
request = ::ActionDispatch::Request.new(env)
original_url = request.original_url
uri = URI.parse(original_url)
uri.query = request.filtered_parameters.to_query if uri.query.present?
uri.to_s
end
end
end
end
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