Firebase Authentication/Identity Platform integration for Hono

This package allows easily integrate Firebase Authentication/Identity Platform to your Hono API project.

Features

• Hono middleware to decode and verify JWT token issued by Firebase Authentication service
• Hono context variable currentUser for you to access any where in your application
• Allowed to custom currentUser shape

Install

With NPM

npm install @fiboup/hono-firebase-auth

With Yarn

yarn add @fiboup/hono-firebase-auth

With pnpm

pnpm add @fiboup/hono-firebase-auth

Usage

Add authentication middleware to your Hono app

import { Hono } from "hono";
import { validateFirebaseAuth } from "@fiboup/hono-firebase-auth";

const app = new Hono();
app.use(
  "*",
  validateFirebaseAuth({
    projectId: "<your_firebase_project_id>",
  })
);

Note: Go to your Firebase project, then visit Project settings for the project id

Configure to catch Firebase JWT token decoding error for Hono

import { Hono } from "hono";
import { JwtDecodeError } from "@fiboup/hono-firebase-auth";

const app = new Hono();

app.onError((err, c) => {
  if (err instanceof JwtDecodeError) {
    return new Response(err.message, {
      status: 401,
    });
  }
  console.log(err);
  return new Response("Uncaught exception", {
    status: 500,
  });
});

Get current user details which is decoded from Firebase JWT token

You can get the current user from Hono context with the key currentUser

import { Hono } from "hono";
import { validateFirebaseAuth } from "@fiboup/hono-firebase-auth";

const app = new Hono();
app.use(
  "*",
  validateFirebaseAuth({
    projectId: "<your_firebase_project_id>",
  })
);

app.get('/me', (c) => {
  const currentUser = c.get('currentUser')
  return c.json(currentUser)
})

To make it type-safe, you can use DefaultFirebaseAuthInjectedVariables

import type { DefaultFirebaseAuthInjectedVariables } from "@fiboup/hono-firebase-auth";

type Variables = DefaultFirebaseAuthInjectedVariables

const app = new Hono<{ Variables: Variables }>()

If you want to custom the context variable key, you can specify in the middleware config

import { Hono } from "hono";
import { validateFirebaseAuth } from "@fiboup/hono-firebase-auth";

const app = new Hono();
app.use(
  "*",
  validateFirebaseAuth({
    projectId: "<your_firebase_project_id>",
    currentUserContextKey: 'custom_current_user'
  })
);

Leave the currentUserContextKey a blank string to disable current user context

Custom current user context info with transformCurrentUser callback

import { Hono } from "hono";
import { validateFirebaseAuth } from "@fiboup/hono-firebase-auth";
import type { DecodedIdToken } from "@fiboup/firebase-auth";

type MyCustomCurrentUser = {
    userId: string
}

const app = new Hono();
app.use(
  "*",
  validateFirebaseAuth({
    transformCurrentUser: <MyCustomCurrentUser>(decodedToken: DecodedIdToken) => {
        return {
            userId: decodedToken.sub,
        }
    }
  })
);

To make your custom current user context type-safe, don't forget to write your custom Hono variable

type Variables = {
    currentUser?: MyCustomCurrentUser
}

const app = new Hono<{ Variables: Variables }>()

License

MIT © Fiboup