Bazel rules for deno

This is very early experimental code to provide basic Deno support under Bazel. This project comes with no guarantees about support, maintenance, or viability, and might be archived at any time.

Depend on this at your own risk!

If we find interest in developing the rules further, we'll fund the project and provide a roadmap of when you could expect a stable release with a minimal viable feature set.

Installation

From the release you wish to use: https://github.com/aspect-build/rules_deno/releases copy the WORKSPACE snippet into your WORKSPACE file.

Now you can use the deno toolchain fetched for your platform.

Usage

Deno binaries

The deno_binary rule creates executable Bazel targets from Deno script files.

load("@aspect_rules_deno//deno:defs.bzl", "deno_binary")

deno_binary(
    name = "example",
    allow = ["write"],
    main = "main.ts",
    unstable_apis = True,
    deps = [
        "helper.ts",
        ":deno_utils",
    ],
)

If executed using bazel run, a Deno script can also make use of Bazel runtime environment variables like $BUILD_WORKSPACE_DIRECTORY and $BUILD_WORKING_DIRECTORY.

Deno libraries

There's no need for a deno_library rule, since Deno will just access imported script files at runtime. If you'd like to make file bundles to include in your deps, just use a filegroup.

filegroup(
    name = "deno_utils",
    srcs = [
        "bazel.ts",
        "console.ts",
    ],
)

Generating outputs

Bazel incrementally transforms the source tree to a bazel-out folder, by spawning subprocesses to run tools. These are called actions and the simplest way to define one is with the "generic rule" genrule

See the examples/genrule folder for the simplest usage: we run deno in a genrule where you fully control the command line used to spawn deno, transforming declared inputs into declared outputs using the toolchain provided by these rules to select the deno runtime for the host and target platform.

Running programs

Both binaries and tests are spawned by Bazel, but without expecting output files. In the case of tests, Bazel treats these as arbitrary programs that exit zero or non-zero.

See the example in the tests/ folder where we use Bazel's sh_test rule to wrap a Deno program. You could similarly use an sh_binary to make a standalone program that can be used with bazel run.