esbuild rules for Bazel
The esbuild rules runs the esbuild bundler tool with Bazel. esbuild is an extremely fast JavaScript bundler written in Go, its current benchmarks show it can be 320x faster that other bundlers
Installation
Add the @bazel/esbuild npm packages to your devDependencies in package.json.
npm install --save-dev @bazel/esbuild
or using yarn
yarn add -D @bazel/esbuild
The esbuild binary is fetched automatically for your platform and is exposed via Bazel toolchains.
To do this, add the esbuild_repositories rule to your WORKSPACE.
You'll need to point it to the repository created by npm_install or yarn_install where the @bazel/esbuild
package is fetched. (Typically, this is npm).
Set the npm_repository attribute to the name of that repository.
npm_install(
name = "npm",
# @bazel/esbuild is a dependency in this package.json
package_json = "//:package.json",
package_lock_json = "//:package-lock.json",
)
load("@build_bazel_rules_nodejs//toolchains/esbuild:esbuild_repositories.bzl", "esbuild_repositories")
esbuild_repositories(npm_repository = "npm")To avoid eagerly fetching all the npm dependencies, this load statement comes from the "Built-in"
@build_bazel_rules_nodejsrepository rather than from@npm. In rules_nodejs 5.0 we intend to fix this layering violation by having the whole esbuild support distributed independently of rules_nodejs, and not require any package to be installed from npm.
See the API docs for esbuild_repositories for ways to customize how Bazel downloads the esbuild package
from npm. Alternatively, advanced users can override the download altogether by defining the esbuild repository
earlier in your WORKSPACE file, so that the maybe inside esbuild_repositories is skipped.
Overview
The esbuild rule can take a JS or TS dependency tree and bundle it to a single file, or split across multiple files, outputting a directory.
load("@npm//@bazel/esbuild:index.bzl", "esbuild")
load("@npm//@bazel/typescript:index.bzl", "ts_project")
ts_project(
name = "lib",
srcs = ["a.ts"],
)
esbuild(
name = "bundle",
entry_point = "a.ts",
deps = [":lib"],
)The above will create three output files, bundle.js, bundle.js.map and bundle_metadata.json which contains the bundle metadata to aid in debugging and resoloution tracing.
To create a code split bundle, set splitting = True on the esbuild rule.
load("@npm//@bazel/esbuild:index.bzl", "esbuild")
load("@npm//@bazel/typescript:index.bzl", "ts_project")
ts_project(
name = "lib",
srcs = ["a.ts"],
deps = [
"@npm//foo",
],
)
esbuild(
name = "bundle",
entry_point = "a.ts",
deps = [":lib"],
splitting = True,
)This will create an output directory containing all the code split chunks, along with their sourcemaps files
esbuild
USAGE
esbuild(name, args, args_json, config, define, define_settings, deps, entry_point, entry_points, external, format, launcher, link_workspace_root, max_threads, metafile, minify, output, output_css, output_dir, output_map, platform, sourcemap, sources_content, splitting, srcs, stamp, target)
Runs the esbuild bundler under Bazel
For further information about esbuild, see https://esbuild.github.io/
ATTRIBUTES
name
(Name, mandatory): A unique name for this target.
args
(Dictionary: String -> String): A dict of extra arguments that are included in the call to esbuild, where the key is the argument name. Values are subject to $(location ...) expansion
Defaults to {}
args_json
(String): Internal use only
Defaults to ""
config
(Label): Configuration file used for esbuild, from the esbuild_config macro. Note that options set in this file may get overwritten. See https://github.com/bazelbuild/rules_nodejs/tree/stable/packages/esbuild/test/plugins/BUILD.bazel for examples of using esbuild_config and plugins. The dependencies of this attribute must provide: Unknown Provider
Defaults to None
define
(Dictionary: String -> String): A dict of global identifier replacements. Values are subject to $(location ...) expansion. Example:
esbuild(
name = "bundle",
define = {
"process.env.NODE_ENV": "production"
},
)See https://esbuild.github.io/api/#define for more details
Defaults to {}
define_settings
(Dictionary: Label -> String): A dict of labels of Starlark build settings and identifiers to be replaced with their values. Example:
load("@bazel_skylib//rules:common_settings.bzl", "string_flag")
string_flag(
name = "api_endpoint",
build_setting_default = "https://example.com/v1",
)
esbuild(
name = "bundle",
define_settings = {
":api_endpoint": "API_ENDPOINT",
},
)The build setting has to provide BuildSettingInfo.
The value is automatically converted to a JS literal.
See https://docs.bazel.build/versions/main/skylark/config.html#predefined-settings for more details on Starlark build settings. The dependencies of this attribute must provide: Unknown Provider
Defaults to {}
deps
(List of labels): A list of direct dependencies that are required to build the bundle
Defaults to []
entry_point
(Label): The bundle's entry point (e.g. your main.js or app.js or index.js)
This is a shortcut for the entry_points attribute with a single entry.
Specify either this attribute or entry_point, but not both.
Defaults to None
entry_points
(List of labels): The bundle's entry points (e.g. your main.js or app.js or index.js)
Specify either this attribute or entry_point, but not both.
Defaults to []
external
(List of strings): A list of module names that are treated as external and not included in the resulting bundle
See https://esbuild.github.io/api/#external for more details
Defaults to []
format
(String): The output format of the bundle, defaults to iife when platform is browser and cjs when platform is node. If performing code splitting or multiple entry_points are specified, defaults to esm.
See https://esbuild.github.io/api/#format for more details
Defaults to ""
launcher
(Label, mandatory): Internal use only
link_workspace_root
(Boolean): Link the workspace root to the bin_dir to support absolute requires like 'my_wksp/path/to/file'. If source files need to be required then they can be copied to the bin_dir with copy_to_bin.
Defaults to False
max_threads
(Integer): Sets the GOMAXPROCS variable to limit the number of threads that esbuild can run with.
This can be useful if running many esbuild rule invocations in parallel, which has the potential to cause slowdown.
For general use, leave this attribute unset.
Defaults to 0
metafile
(Boolean): if true, esbuild creates a metafile along the output
Defaults to True
minify
(Boolean): Minifies the bundle with the built in minification. Removes whitespace, shortens identifieres and uses equivalent but shorter syntax.
Sets all --minify-* flags
See https://esbuild.github.io/api/#minify for more details
Defaults to False
output
(Label): Name of the output file when bundling
output_css
(Label): Declare a .css file will be output next to output bundle.
If your JS code contains import statements that import .css files, esbuild will place the content in a file next to the main output file, which you'll need to declare. If your output file is named 'foo.js', you should set this to 'foo.css'.
output_dir
(Boolean): If true, esbuild produces an output directory containing all output files
Defaults to False
output_map
(Label): Name of the output source map when bundling
platform
(String): The platform to bundle for.
See https://esbuild.github.io/api/#platform for more details
Defaults to "browser"
sourcemap
(String): Defines where sourcemaps are output and how they are included in the bundle. By default, a separate .js.map file is generated and referenced by the bundle. If 'external', a separate .js.map file is generated but not referenced by the bundle. If 'inline', a sourcemap is generated and its contents are inlined into the bundle (and no external sourcemap file is created). If 'both', a sourcemap is inlined and a .js.map file is created.
See https://esbuild.github.io/api/#sourcemap for more details
Defaults to ""
sources_content
(Boolean): If False, omits the sourcesContent field from generated source maps
See https://esbuild.github.io/api/#sources-content for more details
Defaults to False
splitting
(Boolean): If true, esbuild produces an output directory containing all the output files from code splitting for multiple entry points
See https://esbuild.github.io/api/#splitting and https://esbuild.github.io/api/#entry-points for more details
Defaults to False
srcs
(List of labels): Source files to be made available to esbuild
Defaults to []
stamp
(Label): Whether to encode build information into the output. Possible values:
- @rules_nodejs//nodejs/stamp:always:
Always stamp the build information into the output, even in [--nostamp][stamp] builds.
This setting should be avoided, since it potentially causes cache misses remote caching for
any downstream actions that depend on it.
- @rules_nodejs//nodejs/stamp:never:
Always replace build information by constant values. This gives good build result caching.
- @rules_nodejs//nodejs/stamp:use_stamp_flag:
Embedding of build information is controlled by the [--[no]stamp][stamp] flag.
Stamped binaries are not rebuilt unless their dependencies change.
[stamp]: https://docs.bazel.build/versions/main/user-manual.html#flag--stamp The dependencies of this attribute must provide: StampSettingInfo
Defaults to @rules_nodejs//nodejs/stamp:use_stamp_flag
target
(String): Environment target (e.g. es2017, chrome58, firefox57, safari11, edge16, node10, esnext). Default es2015.
See https://esbuild.github.io/api/#target for more details
Defaults to "es2015"
configure_esbuild_toolchain
USAGE
configure_esbuild_toolchain(name, binary, exec_compatible_with)
Defines a toolchain for esbuild given the binary path and platform constraints
PARAMETERS
name
unique name for this toolchain, generally in the form "esbuild_platform_arch"
binary
label for the esbuild binary
exec_compatible_with
list of platform constraints
esbuild_config
USAGE
esbuild_config(name, config_file, srcs, deps, kwargs)
Macro for an esbuild configuration file and its assoicated dependencies
PARAMETERS
name
Unique name for this rule
config_file
The configuration file / entrypoint
srcs
List of source files referenced by the configuration
Defaults to []
deps
List of dependencies required for this configuration
Defaults to []
kwargs
Any other common attributes
esbuild_repositories
USAGE
esbuild_repositories(npm_repository, name, npm_args, kwargs)
Helper for fetching and setting up the esbuild versions and toolchains
This uses Bazel's downloader (via http_archive) to fetch the esbuild package
from npm, separately from any npm_install/yarn_install in your WORKSPACE.
To configure where the download is from, you make a file containing a rewrite rule like
rewrite (registry.nodejs.org)/(.*) artifactory.build.internal.net/artifactory/$1/$2
You can find some documentation on the rewrite patterns in the Bazel sources: UrlRewriterConfig.java
Then use the --experimental_downloader_config Bazel option to point to your file.
For example if you created .bazel_downloader_config you might add to your .bazelrc file:
common --experimental_downloader_config=.bazel_downloader_config
PARAMETERS
npm_repository
the name of the repository where the @bazel/esbuild package is installed by npm_install or yarn_install.
name
currently unused
Defaults to ""
npm_args
additional args to pass to the npm install rule
Defaults to []
kwargs
additional named parameters to the npm_install rule