headers-for-firebase

Transform the headers defined in _headers to the format needed in your firebase.json.

Introduction

Both Netlify sites and Cloudflare Pages support _headers files as a way to define custom headers when serving websites.

If you deploy your website with Firebase Hosting, you may have discovered that it completely ignores _headers files; headers must be defined in a firebase.json file instead, with has a slightly different syntax.

This package grabs your _headers file, parse the rules and convert them into Firebase's format, and insert them within firebase.json's hosting.headers property for you.

Install

npm install headers-for-firebase

Usage

1. Edit your firebase.json to include two comments, where the headers will be included:

   {
       "hosting": {
           "headers": [
   +            /* _headers */
   +            /* end _headers */
           ]
       }
   }

2. Call headers-for-firebase before publishing, either in the CLI or programmatically.

Option 1: Using the CLI

Assuming you have a build script within your package.json that generates your _headers file, write a new postbuild script that calls headers-for-firebase:

{
    "package": "your-package-name",
    "scripts": {
+        "postbuild": "headers-for-firebase"
    }
}

By default headers-for-firebase assumes there are two files: ./_site/_headers and ./firebase.json; you can customize the paths by running

$ headers-for-firebase --headers "./path/to/headers" --firebase "./path/to/firebase.json"

Option 2: Calling it programmatically

Assuming you have a build.js script that generates your _headers file; you can add these two lines:

import { addHeadersToFirebaseConfigFile } from "headers-for-firebase";

// call this function after `_headers` is generated; it will return a Promise
addHeadersToFirebaseConfigFile("./path/to/headers", "./path/to/firebase.json");

API

addHeadersToFirebaseConfigFile(headersPath, firebasePath)

Transform the headers defined in the content of headersPath, and saved them in firebasePath.

Returns a Promise with the number of targets successfully added; rejects if

• any of the paths are unavailable, or
• the content of firebasePath does not include the two required comments.

Author

Carlos Molina Avendaño ©, released under MIT License.