rules_devserver: Web Development Server Bazel Rule

This repository contains a Bazel rule for running a development server. It is intended to be used for local development, and is not intended for production use.

Features

• Live-reload via ibazel and a custom live-reload script.
• Hot swappable JavaScript modules.
• Custom routes for any dependency in the BUILD rule's data attribute.

Pre-requisites

• Bazel 6.0.0 or higher
• ibazel for live-reload
• Linux. This rule has not been tested on other operating systems.

Setup

Workspace

workspace(name = "test_rules_devserver")

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
http_archive(
    name = "rules_devserver",
    strip_prefix = "rules_devserver-0.2.0",
    urls = ["https://github.com/ryanmcdermott/rules_devserver/archive/refs/tags/0.2.0.tar.gz"],
)

Example BUILD file

load("@rules_devserver//devserver:defs.bzl", "devserver")

filegroup(
    name = "index",
    srcs = ["index.html"],
    visibility = ["//visibility:public"]
)

filegroup(
    name = "bundle"
    srcs = ["bundle.js"],
    visibility = ["//visibility:public"]
)

devserver(
    name = "serve",
    port = 8081,
    workspace_name = "test_rules_devserver",
    static_files = {
        "/": [":index", "index.html"],
        "/scripts/bundle.js": [":bundle", "bundle.js"]
    },
    data = [":index", ":bundle"]
)

The static_files attribute is a dictionary of routes to files. The key is the route and the value is a tuple of the [filegroup target, file name]. All targets in the static_files attribute must also be in the data attribute.

Usage of Example BUILD file

ibazel run //:serve

Whenever a file in the data attribute is changed, the server will be live-reloaded.

Hot Swap JavaScript Modules

To hot swap a JavaScript module, add the a data attribute on the <script> tag in the HTML file. For example:

<script type="module" data-hot-swap="true" src="/scripts/bundle.js"></script>

When the server is live-reloaded, the browser will hot swap the JavaScript module, and the host page itself will not reload.