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metamask-extension/development/build/README.md
Mark Stacey 9fd42f1bc2 Fix LavaMoat background policy generation (#12844)
The LavaMoat policy generation script would sporadically fail because
it ran the build concurrently three times, and the build includes
steps that delete the `dist` directory and write to it. So if one build
process tried to write to the directory after another deleted it, it
would fail.

This was solved by adding a new `--policy-only` flag to the build
script, and a new `scripts:prod` task. The `scripts:prod` task only
runs the script tasks for prod, rather than the entire build process.
The `--policy-only` flag stops the script tasks once the policy has
been written, and stops any other files from being written to disk.

This prevents the three concurrent build processes from getting in each
others way, and it dramatically speeds up the process.
2021-11-26 17:14:24 -03:30

62 lines
3.5 KiB
Markdown

# The MetaMask Build System
> _tl;dr_ `yarn dist` for prod, `yarn start` for local development
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`](https://github.com/MetaMask/metamask-extension/blob/develop/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](../../README.md#building-locally).
Generally speaking, the build system consists of [`gulp`](https://npmjs.com/package/gulp) tasks that either manipulate static assets or bundle source files using [Browserify](https://browserify.org/).
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](https://babeljs.io/), specifically using
the [`babelify`](https://npmjs.com/package/babelify) Browserify transform.
Source file bundling tasks are implemented in the [`./development/build/scripts.js`](https://github.com/MetaMask/metamask-extension/blob/develop/development/build/scripts.js).
> Locally implemented Browserify transforms, _some of which affect how we write JavaScript_, are listed and documented [here](./transforms/README.md).
## Usage
```text
Usage: yarn build <entry-task> [options]
Commands:
yarn build prod Create an optimized build for production environments.
yarn build dev Create an unoptimized, live-reloaded build for local
development.
yarn build test Create an optimized build for running e2e tests.
yarn build testDev Create an unoptimized, live-reloaded build for running
e2e tests.
Options:
--build-type The "type" of build to create. One of: "beta", "main"
[string] [default: "main"]
--lint-fence-files Whether files with code fences should be linted after
fences have been removed by the code fencing transform.
The build will fail if linting fails.
Defaults to `false` if the entry task is `dev` or
`testDev`, and `true` otherwise.
[boolean] [default: <varies>]
--lockdown Whether to include SES lockdown files in the extension
bundle. Setting this to `false` is useful e.g. when
linking dependencies that are incompatible with lockdown.
[boolean] [default: true]
--policy-only Stops the build after generating the LavaMoat policy,
skipping any writes to disk.
[boolean] [deafult: false]
--skip-stats Whether to refrain from logging build progress. Mostly
used internally.
[boolean] [default: false]
```