Verified Commit fe580970 authored by Alejandro Rodríguez's avatar Alejandro Rodríguez 🌴
Browse files

Add metadata to headers in Rack middleware

parent c4bc58d3

lib/labkit/middleware/rack.rb

+17 −2
Original line number Diff line number Diff line 
# frozen_string_literal: true



require "action_dispatch"

require "json"



module Labkit

  module Middleware

    HEADER = "X-Gitlab-Meta"



    # This is a rack middleware to be inserted in GitLab-rails

    # It makes sure that there's always a root context containing the correlation

    # id.
@@ -15,8 +18,12 @@ module Labkit 
      end



      def call(env)

        Labkit::Context.with_context(Labkit::Context::CORRELATION_ID_KEY => correlation_id(env)) do

          @app.call(env)

        Labkit::Context.with_context(Labkit::Context::CORRELATION_ID_KEY => correlation_id(env)) do |context|

          status, headers, response = @app.call(env)



          headers[HEADER] = context_to_json(context)



          [status, headers, response]

        end

      end
@@ -29,6 +36,14 @@ module Labkit 
      def request(env)

        ActionDispatch::Request.new(env)

      end



      def context_to_json(context)

        context

          .to_h

          .transform_keys { |k| k.delete_prefix("meta.") }

          .merge("version" => "1")

          .to_json

      end

    end

  end

end

spec/labkit/middleware/rack_spec.rb

+21 −6
Original line number Diff line number Diff line
@@ -2,23 +2,38 @@ 


describe Labkit::Middleware::Rack do

  let(:app) { double("app") }

  let(:correlation_id) { "the id" }

  let(:metadata) { { "feature_category" => "issue_tracking" } }

  let(:header_metadata) { metadata.merge({ "version" => "1", Labkit::Context::CORRELATION_ID_KEY => correlation_id }) }

  let(:env) { {} }

  let(:fake_request) { double("request") }



  before do

    allow(ActionDispatch::Request).to receive(:new).with(env).and_return(fake_request)

    allow(fake_request).to receive(:request_id).and_return(correlation_id)

  end



  describe "#call" do

    it "adds the correlation id from the request to the context" do

      fake_request = double("request")



      expect(ActionDispatch::Request).to receive(:new).with(env).and_return(fake_request)

      expect(fake_request).to receive(:request_id).and_return("the id")

      expect(Labkit::Context).to receive(:with_context).with(a_hash_including(Labkit::Context::CORRELATION_ID_KEY => "the id"))

      expect(Labkit::Context).to receive(:with_context).with(a_hash_including(Labkit::Context::CORRELATION_ID_KEY => correlation_id))



      described_class.new(app).call(env)

    end



    it "calls the app" do

      expect(app).to receive(:call).with(env)

      expect(app).to receive(:call).with(env).and_return([nil, {}, nil])



      described_class.new(app).call(env)

    end



    it "injects meta headers" do

      Labkit::Context.push(metadata)



      expect(app).to receive(:call).with(env).and_return([nil, {}, nil])



      _, headers, _ = described_class.new(app).call(env)



      expect(JSON.parse(headers["X-Gitlab-Meta"])).to eq(header_metadata)

    end

  end

end