How does Shopify app access external networks?

[ben199265]

We are a Shopify Plus merchant. I followed the official case
https://shopify.dev/docs/apps/build/discounts/network-access?extension=javascript
and wanted to build a service network that accesses the external service network to do discount-related functions. However, I built the Shopify application according to the document linked above, and also used remix and ngrok to build local services. However, when I started the Shopify app dev to apply it, the plug-in application did not send any http request at all. Why is this? Has anyone encountered this? Can you teach me what is going on? How can I access the external network?

[ben199265]

This is my shopify.extension.toml configuration
The ngrok URL is normal, I use postman to request everything is normal, the plug-in is not on the market, it is installed in the test store for testing, I don't know if this has any impact, the problem I am facing now is that when I go to add to cart or check out, I can see the log in the local environment, but the http request does not reach ngrok at all, which means there is no request at all, can you help me find out why? Give me some experience, I have done it completely according to the official website's document demo

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api_version = "2025-04"

[[extensions]]

name = "t:name"

handle = "discount-function-js"

type = "function"

description = "t:description"

  [[extensions.targeting]]

  target = "cart.lines.discounts.generate.run"

  input_query = "src/cart_lines_discounts_generate_run.graphql"

  export = "cart-lines-discounts-generate-run"

  [[extensions.targeting]]

  target = "cart.delivery-options.discounts.generate.run"

  input_query = "src/cart_delivery_options_discounts_generate_run.graphql"

  export = "cart-delivery-options-discounts-generate-run"

  [[extensions.targeting]]

  target = "cart.lines.discounts.generate.fetch"

  input_query = "src/cart_lines_discounts_generate_fetch.graphql"

  export = "cart-lines-discounts-generate-fetch"

  [[extensions.targeting]]

  target = "cart.delivery-options.discounts.generate.fetch"

  input_query = "src/cart_delivery_options_discounts_generate_fetch.graphql"

  export = "cart-delivery-options-discounts-generate-fetch"

  [extensions.network_access]

  url = "https://47a7-103-177-222-0.ngrok-free.app/api"

  [extensions.build]

  command = ""

  path = "dist/function.wasm"

[SamDTCSupport]

Hey!

I’ve seen similar issues pop up with Shopify Plus apps trying to connect to external services. A few things I’d check:

• Shopify’s extensions usually can’t make HTTP calls directly from the frontend because of sandbox limits. It’s often better to route those requests through your backend or use an app proxy.

• Make sure your ngrok tunnel is up and the URL hasn’t changed. Even if Postman works, your app might not reach it if the setup isn’t quite right.

• Your config looks good, but sometimes caching or delayed updates can cause issues. Try restarting your dev server and clearing caches to be sure.

• Since you see logs locally but no requests hitting ngrok, maybe the frontend isn’t triggering those calls properly. Adding some debug logs where the calls start can help.

• Also, test in a real or staging store if you can—sometimes test store restrictions affect this.

If this still feels tricky, working with a Shopify Plus agency that’s used to these setups can really speed things up.

Hope this helps!