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Environment variables are now considered as higher-precedence than configuration by our build system. This means that if the same value is set in `.metamaskrc` and in an environment variable, the environment variable is what will be used. Previously the reverse was true, the configuration would take precedence. It is conventional for CLI tools to consider environment variables as higher precedence than configuration. This makes our build system less surprising for most people.
The MetaMask Build System
tl;dr
yarn distfor prod,yarn startfor local development. Add--build-type flaskto build Flask, our canary distribution with more experimental features.
This directory contains the MetaMask build system, which is used to build the MetaMask Extension such that it can be used in a supported browser.
From the repository root, the build system entry file is located at ./development/build/index.js.
Several package scripts invoke the build system.
For example, yarn start creates a watched development build, and yarn dist creates a production build.
Some of these scripts applies lavamoat to the build system, and some do not.
For local development, building without lavamoat is faster and therefore preferable.
The build system is not a full-featured CLI, but rather a script that expects some command line arguments and environment variables. For instructions regarding environment variables, see the main repository readme.
Generally speaking, the build system consists of gulp tasks that either manipulate static assets or bundle source files using Browserify.
Production-ready zip files are written to the ./builds directory, while "unpacked" extension builds
are written to the ./dist directory.
Our JavaScript source files are transformed using Babel, specifically using
the babelify Browserify transform.
Source file bundling tasks are implemented in the ./development/build/scripts.js.
Locally implemented Browserify transforms, some of which affect how we write JavaScript, are listed and documented here.
Usage
See node ./development/build/index.js --help