node.js-Invoking GCloud Function without Authentication

DazWilkin 2020-12-07 22:32:15

Following up on my comment, here's the simplest answer that should work.

NOTE I think you must ensure your Cloud Functions returns appropriate CORS headers

Access-Control-Allow-Origin: *

Access-Control-Allow-Methods: GET

I wrote a Cloud Function in Golang:

package p

import (
    "encoding/json"
    "net/http"
)

type Message struct {
    Name string `json:"name"`
}

func WebPage(w http.ResponseWriter, r *http.Request) {
    m := Message{
        Name: "Freddie",
    }
    w.Header().Set("Access-Control-Allow-Origin", "*")
    w.Header().Set("Access-Control-Allow-Methods", "GET")
    w.Header().Set("Content-Type", "application/json")
    err := json.NewEncoder(w).Encode(m)
    if err != nil {
        http.Error(w, err.Error(), 500)
        return
    }
}

I deployed this Function:

PROJECT="<your-project>"
REGION="<your-region>"
FUNCTION="<your-function>"

gcloud projects create ${PROJECT}

BILLING=$(gcloud beta billing accounts list --format="value(name)")
gcloud beta billing projects link ${PROJECT} --billing-account=${BILLING}

for SERVICE in "cloudbuild" "cloudfunctions"
do
  gcloud services enable ${SERVICE}.googleapis.com \
  --project=${PROJECT}
done

gcloud functions deploy ${FUNCTION} \
--entry-point=WebPage \
--source=. \
--project=${PROJECT} \
--allow-unauthenticated \
--region=${REGION} \
--runtime=go113 \
--trigger-http

You can grab your function's endpoint in curl:

URL=$(\
  gcloud functions describe ${FUNCTION} \
  --project=${PROJECT} \
  --format="value(httpsTrigger.url)")

curl \
--silent \
--include \
--header "Accept: application/json" \
--request GET \
${URL}

Yields:

HTTP/2 200 
access-control-allow-methods: GET
access-control-allow-origin: *
content-type: application/json
...

{"name":"Freddie"}

Then you can GET the value and put it into an HTML id:

<!DOCTYPE html>
<html lang="en">

<body>
<div id="result">/div>

<script>
    const PROJECT = "<your-project>";
    const REGION = "<your-region>";
    const FUNCTION = "<your-function>";

    const ID = "result";

    const URL = `https://${REGION}-${PROJECT}.cloudfunctions.net/${FUNCTION}`;

    fetch(URL,{
        method: "GET",
        headers: {
            "Accept": "application/json"
        }
    })
    .then(resp => resp.json())
    .then(json => JSON.stringify(json))
    .then(html => document.getElementById(ID).innerHTML = html);
</script>
</body>
</html>

I tested this (locally) using Caddy:

docker run \
--rm \
--name=caddy \
--interactive --tty \
--publish=80:80 \
--volume=$PWD/index.html:/usr/share/caddy/index.html \
--volume=caddy_data:/data \
caddy

And then browsing http://localhost:80, I get:

{"name":"Freddie"}

Invoking GCloud Function without Authentication

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