Debug Functions locally

start the functions emulator

We run the functions on their own (serve), or along other emulated services.

npm run serve
firebase emulators:start --only functions
firebase emulators:start --import emulator-data --export-on-exit

Callable functions are designed to be called from the client SDK. We can bypass this requirement locally:

invoke callable functions outside the client SDK

functions:shell starts the functions emulator and starts an interactive CLI shell from which we invoke callable functions with a payload.

firebase functions:shell
npm run shell # alternative

We provide the mandatory data property. It holds the payload:

requestArticles({ data: { name: "Lena" } })

We can also invoke them with curl

curl -s -H "Content-Type: application/json" \
  -d '{ "data": { } }' \
  http://localhost:5001/imagetale/europe-west1/get_images

wire the client to the emulator

We redirect invocations towards the emulated functions, but only on localhost:

if (location.hostname === "localhost") {
    // ...
    connectFunctionsEmulator(functions, "localhost", 5001)
}

invoke emulated HTTP functions

We invoke HTTP functions with a HTTP request. The URL pattern is specific to the emulator.

http://localhost:5001/imagetale/europe-west1/get_images