--- title: Debug traffic flows with cloud endpoints and custom... description: Ngrok's Traffic Policy engine offers a custom-response action that returns a hardcoded, terminating response directly from the ngrok network, without needing... canonical: https://daily.dev/posts/debug-traffic-flows-with-cloud-endpoints-and-custom-responses-fb0wmv4ev twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Debug traffic flows with cloud endpoints and custom responses | daily.dev og:description: Ngrok's Traffic Policy engine offers a custom-response action that returns a hardcoded, terminating response directly from the ngrok network, without needing... og:url: https://daily.dev/posts/debug-traffic-flows-with-cloud-endpoints-and-custom-responses-fb0wmv4ev og:image: https://api.daily.dev/og/posts/FB0wmV4EV.png og:image:alt: Debug traffic flows with cloud endpoints and custom responses og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Debug traffic flows with cloud endpoints and custom responses **[ngrok Blog](https://daily.dev/sources/ngrok)** · 4 min read · 0 upvotes · 0 comments ## Summary Ngrok's Traffic Policy engine offers a custom-response action that returns a hardcoded, terminating response directly from the ngrok network, without needing an upstream service. This trick lets developers use a cloud endpoint as a lightweight sandbox to write and test Traffic Policy rules quickly, including examples like a maintenance page or testing load balancing with the rand.int() macro before wiring up real backend actions like JWT validation or rate limiting. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How can I test ngrok Traffic Policy rules without setting up a real backend service? Use the custom-response action on the on_http_request phase to return a hardcoded response directly from the ngrok network, with no upstream service or agent required. Because it is a terminating action, it can stand in as a fake upstream so you can develop and validate rules like load balancing or header rewriting before wiring up real infrastructure. _daily.dev surfaces practical gateway configuration workflows like this for engineers refining traffic routing._ ### How do I simulate load balancing between two endpoints using ngrok's rand.int() macro? Write a Traffic Policy rule that generates a random integer between 0 and 10 with rand.int(), routing to a second endpoint when the value is 5 or below and falling back to a custom response otherwise. Saving and repeatedly hitting the endpoint shows the response vary between the two paths, validating the load-balancing logic before production use. _Developers weighing traffic-splitting approaches can track gateway feature examples on daily.dev._ --- Tags: [#devtools](https://daily.dev/tags/devtools), [#api-gateway](https://daily.dev/tags/api-gateway) [View this post on daily.dev](https://daily.dev/posts/debug-traffic-flows-with-cloud-endpoints-and-custom-responses-fb0wmv4ev) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Debug traffic flows with cloud endpoints and custom responses","url":"https://daily.dev/posts/debug-traffic-flows-with-cloud-endpoints-and-custom-responses-fb0wmv4ev","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/debug-traffic-flows-with-cloud-endpoints-and-custom-responses-fb0wmv4ev"},"datePublished":"2026-08-23T07:21:08.671Z","dateModified":"2026-08-23T07:23:57.821Z","description":"Ngrok's Traffic Policy engine offers a custom-response action that returns a hardcoded, terminating response directly from the ngrok network, without needing...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/4c7a4ee4c6b73f291e08282eb102bdce?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/4c7a4ee4c6b73f291e08282eb102bdce?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"ngrok Blog","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"ngrok Blog","logo":"https://media.daily.dev/image/upload/s--718XXxvE--/f_auto,q_auto/v1787469610/logos/ngrok?_a=BAMAMicg0","url":"https://daily.dev/sources/ngrok"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/debug-traffic-flows-with-cloud-endpoints-and-custom-responses-fb0wmv4ev","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"devtools,api-gateway","timeRequired":"PT4M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"ngrok Blog","item":"https://daily.dev/sources/ngrok"},{"@type":"ListItem","position":3,"name":"Debug traffic flows with cloud endpoints and custom responses"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/debug-traffic-flows-with-cloud-endpoints-and-custom-responses-fb0wmv4ev#faq","mainEntity":[{"@type":"Question","name":"How can I test ngrok Traffic Policy rules without setting up a real backend service?","acceptedAnswer":{"@type":"Answer","text":"Use the custom-response action on the on_http_request phase to return a hardcoded response directly from the ngrok network, with no upstream service or agent required. 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