Firebase | Creating a Cloud Function Using Firebase CLI and TypeScript

Overview

Firebase cloud functions let’s you run a piece of code in cloud without managing the servers. This is quite helpful when you just want to manage your code and not to worry about the servers executing the code. This pattern is also known as serverless architecture.

These cloud functions can be triggered by multiple events such as an http request, scheduled time or in response to changes in Realtime Database and perform the intended job.

In this post we will see how we can create a simple Firebase cloud function using Firebase CLI and then deploy it to Firebase. We will use TypeScript to write the function.

Steps for creating the Cloud Function

Let’s create and deploy a Firebase cloud function.

Installing Firebase CLI

Firebase cloud functions are created and deployed using Firebase CLI, so let’s install the Firebase CLI globally. Type following command on command prompt.

npm install -g firebase-tools

Login to Firebase CLI

We need to authenticate to Firebase to create and deploy cloud functions, authenticate to Firebase using following command.

firebase login

This will open a browser window to authenticate.

If you are logged in with another account then you can logout first using following.

firebase logout

Choose the account to login.

Allow, to grant permissions to Firebase CLI.

On Allow following success screen will be presented.

And in command prompt message like following will be logged.

Creating a Firebase Cloud Function Project

Create a directory for the project.

mkdir firebase-function-demo

Change to project directory.

cd firebase-function-demo

Open the directory with Visual Studio code or any other editor.

code .

Initialize Firebase functions project

firebase init functions

Accept the confirmation.

Choose the appropriate option for you. In my case I chose “Use an existing project“, because I have already created the Firebase project.

Next I chose the project from the presented list.

For this example we are going to use the TypeScript, so choose the TypeScript.

Choose Y if you want to use ESLint.

Select Y to install the dependencies.

Your project structure should appear like this so far.

Creating a Cloud Function

We will use the sample helloworld cloud function created by the Firebase CLI for this example.

Open selected index.ts.

index.ts contains commented sample function.

Uncomment the code, and save the file.

File contains one sample http request based cloud function. Which will log following.

"Hello logs!", {structuredData: true}

and return following response.

"Hello from Firebase!"

In the same file more functions can be added, for example we can add another scheduled function like following.

export const scheduledJob = functions.pubsub.schedule("every 5 minutes")
    .onRun(()=>{
      console.log("This will be run every 5 minutes.");
      return null;
    });

This scheduled function will run every five minutes,

cron expression can be added like following to define trigger time for scheduled functions.

export const  scheduledFunctionCrontab = functions.pubsub.schedule('5 11 * * *')
  .timeZone('America/New_York') // Users can choose timezone - default is America/Los_Angeles
  .onRun((context) => {
  console.log('This will be run every day at 11:05 AM Eastern!');
  return null;
});

Deploying cloud function

Let’s deploy the sample code in index.ts to cloud.

Execute the following command on command prompt.

firebase deploy

On successful function deployment, function url will be provided.

Paste the URL in the browser.

and you will get the response like below from cloud function.

Great! Our cloud function is successfully deployed and responding to http request.

Navigate to Firebase project and select functions.

and you should be able to see your cloud function.

You can switch to Logs tab to see the logs of the cloud function.

Congratulations! We have just deployed our first simple cloud function.

Conclusion

In this post we learned how we can create a Firebase Cloud Function and deploy to Firebase. We started with how to install the Firebase CLI globally, and how to authenticate to it. Then we created a template project for cloud function using Firebase CLI and then deployed and tested the cloud function.

Hope you like this!

Please leave your feedback or any query you have.

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