rules_oci_bootstrap - Bazel rules to bootstrap from an OCI registry

These rules implement repository rules to pull blobs from an oci registry, including authentication from docker credential helpers. Serving the primary use-case of bootstrapping a Bazel WORKSPACE solely from a OCI artifact registry.

Motivation

At Datadog we have a globally distributed OCI artifact registry that we pull artifacts to be used at build time from.

In the past we checked in large Go binaries into source control that knew how to pull from the registry, however this binary became quickly disconnected from the actual source, slowed down pulling times and was unable to be cached by Bazel because it wasn't using rctx.download.

This implementation is purely Bazel Starlark-based, using the repository_ctx apis so that blobs pulled by these rules can be cached by Bazel.

In addition to issues mentioned above, we have multiple network partitions where the registry defined in the WORKSPACE file is not always available. In this case, a script that wraps the bazel command can override the registry host via the OCI_REGISTRY_HOST environment variable.

Setup

To import this repository while on MacOS, run the following and then paste into your WORKSPACE file:

echo """
git_repository(
    name = \"rules_oci_bootstrap\",
    remote = \"https://github.com/DataDog/rules_oci_bootstrap.git\",
    commit = \"$(git ls-remote ssh://git@github.com/DataDog/rules_oci_bootstrap | head -1 | cut -f 1)\",
)
""" | pbcopy

On Linux run the following command to get the latest commit:

git ls-remote ssh://git@github.com/DataDog/rules_oci_bootstrap | head -1 | cut -f 1

Then substitiute $COMMIT in the following block, which you can paste in your WORKSPACE file:

git_repository(
    name = "rules_oci_bootstrap",
    remote = "https://github.com/DataDog/rules_oci_bootstrap.git",
    commit = "$COMMIT",
)

Usage

To pull a single file, which can be referenced at @test_blob//:blob, you can add something like the following to your WORKSPACE:

load("@rules_oci_bootstrap//:defs.bzl", "oci_blob_pull")

oci_blob_pull(
    name = "test_blob",
    registry = "registry.example.com",
    repository = "my/repository",
    digest = "sha256:abcd...",
)

To pull a .tar.gz (or any other archive), you can do something like this, however you may want to provide your own BUILD file via build_file_content:

load("@rules_oci_bootstrap//:defs.bzl", "oci_blob_pull")

oci_blob_pull(
    name = "test_blob",
    registry = "registry.example.com",
    repository = "my/repository",
    digest = "sha256:abcd...",
    extract = True,
    type = "tar.gz",
)

NOTE: The registry can be overriden by setting OCI_REGISTRY_HOST, which will override the registry parameter. This should be done by a script that wraps bazel when the user is in a different network partition, when not provided the registry attribute will serve as the default.