bazel/platform/BUILD.bazel

# https://github.com/bazelbuild/bazel-toolchains/blob/master/rules/exec_properties/exec_properties.bzl
load("@bazel_toolchains//rules/exec_properties:exec_properties.bzl", "create_rbe_exec_properties_dict")

# https://bazel.build/concepts/platforms-intro
# https://bazel.build/docs/platforms
platform(
    name = "linux_x64_hermetic",
    constraint_values = [
        "@platforms//os:linux",  # https://github.com/bazelbuild/platforms/blob/main/os/BUILD
        "@platforms//cpu:x86_64",  # https://github.com/bazelbuild/platforms/blob/main/cpu/BUILD
        ":use_hermetic_toolchain",
    ],
    # We specify exec_properties because we have an RBE instance that matches this platform.
    # exec_properties specify some information that is passed along the Remote Execution API
    # (REAPI) to the dispatcher which will use it to direct the request to the appropriate
    # machine/worker, using the Remote Worker API (RWAPI).
    # http://go/skolo-rbe
    # These properties will be ignored when running locally, but we must specify them if we want
    # the action cache to treat things built on a local Linux machine to be the same as built on
    # a Linux RBE worker (which they should, assuming our hermetic toolchain *is* hermetic).
    # See https://github.com/bazelbuild/bazel/blob/f28209df2b0ebeff1de0b8b7f6b9e215d890e753/src/main/java/com/google/devtools/build/lib/actions/ActionKeyCacher.java#L67-L73
    # for how the exec_properties and execution platform impact the action cache.
    exec_properties = create_rbe_exec_properties_dict(
        container_image = "docker://gcr.io/skia-public/rbe_linux@sha256:654139e5cecb163f80a7d18e2b2da6c758ebe6325d2d9c41d9facf58e1b3f799",
        os_family = "Linux",
        pool = "gce_linux",
    ),
)

platform(
    name = "mac_x64_hermetic",
    constraint_values = [
        "@platforms//os:macos",
        "@platforms//cpu:x86_64",
        ":use_hermetic_toolchain",
    ],
)

platform(
    name = "mac_arm64_hermetic",
    constraint_values = [
        "@platforms//os:macos",
        "@platforms//cpu:arm64",
        ":use_hermetic_toolchain",
    ],
)

platform(
    name = "host_with_hermetic_toolchain",
    constraint_values = [
        ":use_hermetic_toolchain",
    ],
    parents = ["@local_config_platform//:host"],
)

# This constraint allows us to force Bazel to resolve our hermetic toolchain to build
# the target and not a default one (e.g. on the Linux RBE instance). We do this by
# adding the constraint to our platforms that describe the target we want Bazel to build for.
# https://bazel.build/reference/be/platform#constraint_setting
constraint_setting(name = "skia_hermetic_toolchain")

constraint_value(
    name = "use_hermetic_toolchain",
    constraint_setting = ":skia_hermetic_toolchain",
    visibility = ["//visibility:public"],
)