build/bazel/BUILD.gn

# Copyright 2022 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import("//build/assembly/sshd_config.gni")
import("//build/bazel/bazel_inputs.gni")
import("//build/bazel/bazel_workspace.gni")
import("//build/bazel/legacy_ninja_build_outputs.gni")
import("//build/images/vbmeta.gni")
import("//build/info/info.gni")
import("//build/product.gni")
import("//build/toolchain/rbe.gni")
import("//src/connectivity/policy/netcfg/delegated_network_provisioning.gni")

assert(
    current_toolchain == default_toolchain,
    "This BUILD.gn file should only be parsed in the default toolchain, to prevent generating Bazel workspace multiple times.")

# A GN target used to generate at GN-gen time a bazel inputs manifest file
# under the following path which is hard-coded in toplevel.WORKSPACE.bazel:
#
# $BAZEL_TOPDIR/legacy_ninja_build_outputs.inputs_manifest.json
#
# See bazel_inputs.gni comments for details on the manifest file format,
# and repository_rules.bzl:bazel_inputs_repository() to see how it is parsed
# to generate an external repository for the Bazel project.
#
# It is possible to build this target to ensure that all Ninja outputs seen
# by the Bazel workspace are properly generated, as in:
#
#    fx build build/bazel:legacy_ninja_build_outputs
#
# IMPORTANT: Nothing in the GN graph should depend on this directly, except
# the top-level //:root_targets group in //BUILD.gn, to ensure
# that its output is generated at gn-gen time.
#
# Doing so allows breaking the testonly boundary, as required to allow
# non-testonly bazel_action() targets to depend on
# :generate_main_workspace below, without depending on this target.
#
generate_bazel_inputs_manifest("legacy_ninja_build_outputs") {
  testonly = true

  output = bazel_inputs_manifest

  # IMPORTANT: All bazel_input_xxx() targets must be reachable from this
  # dependencies list!
  inputs_deps = gn_labels_for_bazel_inputs + extra_gn_labels_for_bazel_inputs
}

action("generate_main_workspace") {
  script = "//build/bazel/scripts/update_workspace.py"

  # The update script tracks the file and directory entries of FUCHSIA_DIR
  # and will update the workspace if they change (i.e. if a file or
  # directory is added to / removed from FUCHSIA_DIR itself). However,
  # there is no way for Ninja to track these changes, and thus no way
  # to enforce the action to be run when this happens, even though these
  # are rare occurences, that could happen in the following cases:
  #
  # - A developer manually adds or removes a file to/from FUCHSIA_DIR.
  #   In this case, manually calling the script is needed, and this
  #   can be done by invoking any `fx bazel ...` command (even
  #   `fx bazel version`) or `fx build bazel_workspace`.
  #
  # - A `jiri update` modifies the content of FUCHSIA_DIR. Depend on
  #   the top-level //.git/index file to detect this. Note that the
  #   script will not necessarily update the workspace in this case,
  #   this simply ensures that it is run to do its checks.
  #
  # - A manual `git checkout HEAD^ -- .` command will modify the local
  #   workspace without modifying the index, so also depend on
  #   //.git/HEAD to detect this.
  #
  inputs = [
    "//.git/index",
    "//.git/HEAD",

    # The bazel prebuilt is an implicit input for the script.
    "//prebuilt/third_party/bazel/${host_os}-${host_cpu}/bazel",

    # The script expands these templates
    "//build/bazel/templates/template.bazel.sh",
    "//build/bazel/templates/template.bazelrc",
    "//build/bazel/templates/template.remote_services.bazelrc",
    "//build/bazel/templates/template.platform_mappings",

    # The script reads this configuration file
    "//build/bazel/config/main_workspace_top_dir",

    # The script imports these python files
    "//build/bazel/scripts/check_ninja_build_plan.py",
    "//build/bazel/scripts/compute_content_hash.py",

    # The script reads RBE configs
    rewrapper_config_file,
    reproxy_config_file,
  ]

  # This dependency is needed to properly populate the @fuchsia_sdk repository.
  deps = [ "//build/bazel/bazel_sdk:idk" ]

  # This dependency is needed to properly populate the @internal_sdk repository
  # used experimentally to migrate non-SDK GN targets to Bazel
  # (see https://fxbug.dev/42063353).
  deps += [ "//sdk:platform" ]

  depfile = "${target_gen_dir}/${target_name}.d"

  outputs = [
    # LINT.IfChange
    "${bazel_main_top_dir}/bazel",
    "${bazel_main_top_dir}/download_config_file",
    "${bazel_main_top_dir}/generated-info.json",
    "${bazel_main_top_dir}/workspace/.bazelrc",
    "${bazel_main_top_dir}/workspace/fuchsia_build_generated/args.json",
    "${bazel_main_top_dir}/workspace/fuchsia_build_generated/git",
    "${bazel_main_top_dir}/workspace/fuchsia_build_generated/jiri_snapshot.xml",

    # The list of content hash files
    "${bazel_main_top_dir}/workspace/fuchsia_build_generated/bazel_rules_fuchsia.hash",
    "${bazel_main_top_dir}/workspace/fuchsia_build_generated/boringssl.hash",
    "${bazel_main_top_dir}/workspace/fuchsia_build_generated/com_google_googletest.hash",
    "${bazel_main_top_dir}/workspace/fuchsia_build_generated/fuchsia_clang.hash",
    "${bazel_main_top_dir}/workspace/fuchsia_build_generated/fuchsia_sdk.hash",
    "${bazel_main_top_dir}/workspace/fuchsia_build_generated/internal_sdk.hash",
    "${bazel_main_top_dir}/workspace/fuchsia_build_generated/prebuilt_clang.hash",
    "${bazel_main_top_dir}/workspace/fuchsia_build_generated/prebuilt_python.hash",

    # Other files.
    "${bazel_main_top_dir}/workspace/platform_mappings",
    "${bazel_main_top_dir}/workspace/WORKSPACE.bazel",

    # LINT.ThenChange(scripts/update_workspace.py)
  ]

  args = [
    "--gn_output_dir",
    rebase_path(root_build_dir, root_build_dir),
    "--target_arch",
    target_cpu,
    "--depfile",
    rebase_path(depfile, root_build_dir),
  ]

  # The generated wrapper includes the absolute path of the Ninja output
  # directory, which will be read by Bazel repository rules during workspace
  # setup.
  no_output_dir_leaks = false
}

# Generate a symlink to the @fuchsia_sdk repository, after ensuring it was
# properly populated by Bazel. The symlink has a stable path of
# $BAZEL_TOPDIR/fuchsia_sdk while the actual location of the repository
# depends on Bazel internals (e.g. whether BzlMod is enabled or not).
action("generate_fuchsia_sdk_repository") {
  script = "//build/bazel/scripts/generate-fuchsia-sdk-symlink.py"
  outputs = [ "$bazel_main_top_dir/fuchsia_sdk" ]
  deps = [ ":generate_main_workspace" ]
  inputs = get_target_outputs(deps[0])
  args = [
    "--bazel-launcher",
    rebase_path(inputs[0], root_build_dir),
    "--output-symlink",
    rebase_path(outputs[0], root_build_dir),
  ]
  metadata = {
    # Used by the //:bazel_sdk_info build API module target.
    bazel_sdk_info = [
      {
        location = rebase_path(outputs[0], root_build_dir)
      },
    ]
  }

  # This script invokes Bazel directly. Use console pool to prevent
  # concurrent bazel invocations.
  pool = "//:console($default_toolchain)"

  # This cannot be hermetic as well since it creates a ton of
  # files in the output base that cannot be listed in advance.
  hermetic_deps = false
}

# Generate a build_args.bzl file that contains Bazel-specific constant
# declarations that match the current build configuration found in args.gn.
#
# NOTE: This is deprecated, use @fuchsia_build_info//:args.bzl to get the
# same constants now. This GN targets will be removed once the last
# //vendor/... references to it have been removed.
#
# Note that another way to pass configuration information is to add
# specific lines to the project's auto-generated .bazelrc file, or even
# to set specific options in the Bazel launcher script.
#
_build_args_bzl_output = "${target_out_dir}/build_args.bzl"
_build_args_bzl_target = "build_args.bzl.generated"
generated_file(_build_args_bzl_target) {
  output_conversion = "list lines"
  contents = [ "# Auto-generated - DO NOT EDIT" ]

  # Export use_vbmeta boolean flag.
  # Boolean values are capitalized differently in GN and Bazel ...
  if (use_vbmeta) {
    contents += [ "use_vbmeta = True" ]
  } else {
    contents += [ "use_vbmeta = False" ]
  }

  # Pass the authorized_ssh_keys_path GN arg to bazel, if it was set in args.gn
  #
  # This can't be directly specified within Bazel rules as it's really meant to
  # be a configuration argument for the build.
  if (authorized_ssh_keys_label != false) {
    contents +=
        [ "authorized_ssh_keys_label = \"${authorized_ssh_keys_label}\"" ]
  } else {
    contents += [ "authorized_ssh_keys_label = None" ]
  }

  # Pass the delegated_network_provisioning GN arg to bazel.
  if (delegated_network_provisioning) {
    contents += [ "delegated_network_provisioning = True" ]
  } else {
    contents += [ "delegated_network_provisioning = False" ]
  }

  # Pass the product name to Bazel.
  contents += [ "build_info_product = \"${build_info_product}\"" ]

  outputs = [ _build_args_bzl_output ]
}

bazel_input_resource("build_args_bazel_inputs") {
  sources = [ _build_args_bzl_output ]
  outputs = [ "build_args.bzl" ]
  deps = [ ":${_build_args_bzl_target}" ]
}

group("tests") {
  testonly = true
  deps = [
    "bazel_sdk:tests",
    "scripts:tests",
    "tests",
  ]
}