Proxy as a service

Azure Functions is a lightweight way to quickly expose an API, the “serverless” way.

Now I wanted to proxy another API to clients (to avoid having to expose the API key and have a future extension point), so I reached for Azure Functions again. Just create an HTTP trigger to act as the proxy and forward calls to the other API, right?

Apparently this use case is already handled by Azure Functions Proxies

You literally just declare the proxy and it works, nice.
Add a proxies.json in the root of your Azure Functions app (assuming you are programming it, if you use the portal, just go to the Proxies node and follow the self -explanatory UI)

{
  "$schema": "http://json.schemastore.org/proxies",
  "proxies": {
    "name_your_proxy": {
      "matchCondition": {
        "methods": [ "POST" ],
        "route": "/api/proxy_call"
      },
      "backendUri": "https://the-api-you-want-to-proxy.com",
      "requestOverrides": {
        "backend.request.headers.example-secret": "dummy-secret" 
      }
    }
  }
}

Publish this and you can call your Azure Functions app on /api/proxy_call, which forwards the call to https://the-api-you-want-to-proxy.com while adding the header with the secret you don’t want to expose to your clients. Simple!

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