Log when rate limit is hit

services/web/app/coffee/Features/Security/RateLimiterMiddlewear.coffee

@@ -1,4 +1,5 @@
 RateLimiter = require "../../infrastructure/RateLimiter"
+logger = require "logger-sharelatex"
 
 module.exports = RateLimiterMiddlewear =
 	###
@@ -22,16 +23,18 @@ module.exports = RateLimiterMiddlewear =
 			params.push user_id
 			if !opts.endpointName?
 				throw new Error("no endpointName provided")
-			RateLimiter.addCount {
+			options = {
 				endpointName: opts.endpointName
 				timeInterval: opts.timeInterval or 60
 				subjectName:  params.join(":")
 				throttle:     opts.maxRequests or 6
-			}, (error, canContinue)->
+			}
+			RateLimiter.addCount options, (error, canContinue)->
 				return next(error) if error?
 				if canContinue
 					next()
 				else
+					logger.warn options, "rate limit exceeded"
 					res.status(429) # Too many requests
 					res.write("Rate limit reached, please try again later")
 					res.end()

services/web/test/UnitTests/coffee/Security/RateLimiterMiddlewearTests.coffee

@@ -7,6 +7,7 @@ describe "RateLimiterMiddlewear", ->
 	beforeEach ->
 		@RateLimiterMiddlewear = SandboxedModule.require modulePath, requires:
 			'../../infrastructure/RateLimiter' : @RateLimiter = {}
+			"logger-sharelatex": @logger = {warn: sinon.stub()}
 		@req =
 			params: {}
 			session: {}
@@ -79,4 +80,14 @@ describe "RateLimiterMiddlewear", ->
 				
 			it "should not continue", ->
 				@next.called.should.equal false
+				
+			it "should log a warning", ->
+				@logger.warn
+					.calledWith({
+						endpointName: "test-endpoint"
+						timeInterval: 42
+						throttle: 12
+						subjectName: "#{@project_id}:#{@doc_id}:#{@user_id}"
+					}, "rate limit exceeded")
+					.should.equal true