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Prerequisites:

  • A GCP account for Google Cloud functions.
  • Install Google Cloud SDK.
  • An Upstash account for Serverless Redis.

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Step 1: Init the Project

  • Create a folder, then run npm init inside the folder.

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Step 2: Install a Redis Client

Our only dependency is redis client. Install go-redis via npm install ioredis

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Step 3: Create a Redis Database

Create a Redis database from Upstash console. Select the GCP US-Central-1 as the region. Free tier should be enough. It is pretty straight forward but if you need help, check getting started guide. In the database details page, click the Connect button. You will need the endpoint and password in the next step.

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Step 4: The function Code

Create index.js as below: 
var Redis = require("ioredis");

if (typeof client === "undefined") {
  var client = new Redis("rediss://:YOUR_PASSWORD@YOUR_ENDPOINT:YOUR_PORT");
}

exports.helloGET = async (req, res) => {
  let count = await client.incr("counter");
  res.send("Page view:" + count);
};
This example uses ioredis, you can copy the connection string from the Node tab in the console.
The code simply increments a counter in Redis database and returns its value in json format.

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Step 5: Deployment

Now we are ready to deploy our API. Deploy via: 
gcloud functions deploy helloGET \
--runtime nodejs14 --trigger-http --allow-unauthenticated
You will see the URL of your Cloud Function. Click to the URL to check if it is working properly. 
httpsTrigger:
securityLevel: SECURE_OPTIONAL
url: https://us-central1-functions-317005.cloudfunctions.net/helloGET
In case of an issue, you can check the logs of your Cloud Function in the GCP console as below.