CONTRIBUTING.md

Firebase CLI Contributing Guide

Overview

The Firebase CLI is a command-line tool to allow developers simple access to Firebase services. The CLI is built to be a general-purpose tool for interacting with Firebase, but it is particularly concerned with tasks related to deployment and interaction between a developer's local project directory and Firebase.

Audience

If you are a developer interested in contributing to the CLI, this is the documentation for you! This guide describes how to be successful in contributing to our repository.

Getting Started

The Firebase CLI is generally developed in the open on GitHub in the firebase/firebase-tools repo. We at Firebase even do our work on the CLI directly within this repo whenever possible.

If you're interested in contributing code, get started by making a fork of the repository for your GitHub account.

Contribution Process

The preferred means of contribution to the CLI is by creating a branch in your own fork, pushing your changes there, and submitting a Pull Request to the master branch of firebase/firebase-tools.

If you believe that your change should be noted in the changelog, please also add an entry to the CHANGELOG.md file. This log is emptied after every release and is used to generate the release notes posted in the Releases page. Markdown formatting is respected (using the GitHub style).

NOTE: Any new files added to the repository must be written in TypeScript and must include unit tests. There are very few exceptions to this rule.

After your Pull Request passes the tests and is approved by a Firebase CLI team member, they will merge your PR. Thank you for your contribution!

Setting up your development environment

When working on the Firebase CLI, you want to work using a clone of the project.

Link your local repository to your environment

After cloning the project, use npm link to globally link your local repository:

git clone git@github.com:firebase/firebase-tools.git
cd firebase-tools
npm install # must be run the first time you clone
npm link  # installs dependencies, runs a build, links it into the environment

This link makes the firebase command execute against the code in your local repository, rather than your globally installed version of firebase-tools. This is great for manual testing.

Test locally while making changes

After you link your local repository to your environment, you may want to run npm run build:watch in a separate terminal window to watch your local repository for any changes and rebuild your source code when it does. These updates will continue to work without having to run npm link repeatedly.

Detect what version of firebase-tools is being used

To determine if your version of firebase-tools is executing against your npm link’d repository, run npm ls to print out global linked modules:

npm ls -g --depth=0 --link=true

# The output might resemble:
# /Users/{user}/.nvm/versions/node/v8.16.0/lib
# └── firebase-tools@7.14.0 -> /Users/{user}/Repositories/firebase-tools

Unlink your local repository

To un-link firebase-tools from your local repository, you can do any of the following:

• run npm uninstall -g firebase-tools
• run npm unlink in your local repository
• re-install firebase-tools globally using npm i -g firebase-tools

Lint, Build, and Tests

While you're working on changes (and especially when preparing a Pull Request), make sure all the applicable tests will pass with your changes.

The short version: run npm test in your local repository to run the majority of the tests that are run by Firebase's CI systems.

Lint

We use eslint to do static analysis of all JavaScript and TypeScript files. Generally speaking, eslint generates a lot of warnings, especially when it comes to JavaScript files (because most of them are older code). A long-term goal for Firebase is to eliminate most of these warnings in the codebase, but it's a long process.

Note that npm test only errors if the linter finds errors in your codebase. So, if you want to fix warnings for your changed files, you can run either of the following commands:

• Run npm run lint to view all warnings in your codebase.
• Run npm run lint:changed-files to view only the warnings of files changed between your working branch and your copy of master. For this reason, it’s important to keep your master up-to-date; otherwise, you might see unnecessary warnings.

We also support an ongoing effort to convert existing JavaScript into TypeScript. If you do a conversion of this nature, the new TypeScript file should be as devoid of any lint warnings as possible. When you send your Pull Request for review, you might be asked to run npm run lint:changed-files and clean up any issues that arise.

Build

Since we use TypeScript, we compile our codebase to JavaScript in our deployment process.

• To do a development build, run npm run build.
• To trigger the production build, run npm run prepare. The production build has several differences from the development build (for example, it doesn't include source maps).

Tests

Firebase runs a number of tests on pushes to the repository as well as on Pull Requests. The majority of these tests are invoked via npm run mocha, and we recommend that you run them locally with the same command.

However, some integration tests require a little more setup, so it’s best to allow them to be run by the GitHub CI testing. There are additional integration tests that GitHub CI will run when code is pushed to GitHub, but some of them are unavailable to Pull Requests coming from forks of the repository.

Repo structure

path	description
src	Contains shared/support code for the commands
src/bin	Contains the runnable script. You shouldn't need to touch this content.
src/commands	Contains code for the commands, organized by one-file-per-command with dashes.
src/test	Contains test helpers. Actual tests (*.spec.ts) should be colocated with source files.
templates	Contains static files needed for various reasons (init templates, login success HTML, etc.)

Building CLI commands

IMPORTANT: The Firebase CLI is subject to Firebase API Council review and approval. Any major new functionality must go through API review. The Firebase CLI team will spearhead this process internally for external contributions; this process can take a few weeks for large API changes.

Setting up a new command

Create a file for your command

First, create a new file in src/commands for your new command, replacing colons with dashes where appropriate. Populate the file with this basic content:

import { Command } from "../command";

// `export default` is used for consistency in command files.
export const command = new Command("your:command")
  .description("a one-line description of your command")
  // .option("-e, --example <requiredValue>", "describe the option briefly")
  // .before(requireConfig) // add any necessary filters and require them above
  // .help(text) // additional help to be visible with --help or the help command
  .action(async (options) => {
    // options will be available at e.g. options.example
    // this should return a Promise that resolves to a reasonable result
  });

Here are a few style notes:

• Command names
  • may be namespaced using colons
  • should be all lower-case letters
• Arguments (in the command or an option)
  • should be lowerCamelCase
• Descriptions (of the command or an option)
  • must be a single brief statement
  • should not start with a capital letter
  • must not end with a punctuation mark

If you want to provide more descriptive help than one line can generally provide, the Command.help method accepts a long-form string to display for the --help flag or the help command.

Build the Command object

Command provides a number of features to implement a command:

• Options: To add an option, use .option() as in the example above. All options should have a short name and a long name, with multiple words in the long name separated by dashes. Options will be made available directly on the options object passed into the command's action.
• Arguments: If your command takes an argument, you can append <argName> (required) or [argName] (optional) to the declaration in new Command(). This pattern works for options too.
• Befores: The Firebase CLI comes with a number of ready-made .before() filters to do things like require a Firebase project directory, require authentication, require access to the current project, etc. To use these filters, require them from the src directory and add a .before(fnName) to your command declaration.

Load the command

Next, go to command/index.js, then add a line to load the command, for example:

client.use = loadCommand("use");

NOTE: loadCommand handles commands written in either JavaScript or TypeScript; no special handling should be required.

Making authenticated API calls

Your command likely needs to make authenticated API calls. The Firebase CLI uses standard Google OAuth access tokens for all requests and is built for direct REST calls (as opposed to using, for example, the googleapis wrapper module). Before you can make an authenticated call, you need to declare some level of authorization. There are two .before() filters that you can use:

• requireAuth: generally requires a user to be logged in to run the command, but does not require project-specific authorization. It is used in commands like firebase projects:list for account-level calls.
• requirePermissions: requires that the authorized account have certain roles on the active project specified either by firebase use in a project directory or with the --project flag on the command itself. The second argument should be an array of granular IAM permissions, such as firebasehosting.sites.update.

Designing scriptable commands

The Firebase CLI is designed to be require-able as a standard Node module. Commands are namespaced functions:

import * as cli from "firebase-tools";
cli.projects.list();
cli.functions.log();

You don't need to do anything special to support scriptability, simply ensure that your action returns or resolves a useful value. For instance, a list command should return an array of objects.

Logging and terminal formatting

The Firebase CLI has a central logger available in src/logger. You should never use console.log() when displaying output to the user.

import { logger } from "../logger";

logger.info("This text will be displayed to the end user.");
logger.debug("This text will only show up in firebase-debug.log or running with --debug.");

In addition, the colorette Node.js library should be used for color/formatting of the output:

import { green, bold, underline } from "colorette";

// Generally, prefer template strings (using `backticks`), but this is a formatting example:
const out = "Formatting is " + bold(underline("fun")) + " and " + green("easy") + ".";

Colors will automatically be stripped from environments that do not support them, so you should feel free to include output formatting. A few conventions exist for output formatting:

• Use the color red only for error text.
• Use bold to call out identifiers (such as product IDs).
• Use the color cyan as a prefix color to categorize output.

Handling errors

By default, the Firebase CLI will handle all unrecognized errors by displaying an "Unknown Error" to the user and logging information to firebase-debug.log. These also return exit code 2.

To handle "expected" errors (for instance, a parse error in a user-provided file), throw a FirebaseError with a friendly error message. The original error may be provided as well. Here's an example:

import { bold } from "colorette";
import { FirebaseError } from "../error";

async function myFunc(projectId: string): void {
  try {
    return await somethingThatMayFail(projectId);
  } catch (err: any) {
    throw FirebaseError(`Project ${bold(projectId)} caused an issue.', { original: err });
  }
}

Testing

Testing your command

You can manually test your new command by globally linking any firebase commands to the local copy of the CLI rather than the public copy. Refer to "Development Setup" for how to do this.

It might also be helpful to run commands with the --debug flag for more verbose output. This output will be streamed to the terminal and saved inside a firebase-debug.log file that is created in your local repository.

cd firebase-tools
npm link

cd path/to/test/project
firebase <command> --debug