Bazel CI |
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https://github.com/bazelbuild/bazel-toolchains is a repository where Google hosts the source code for a CLI tool that can be used to generate Bazel toolchain configs. These configs are required to configure Bazel to issue commands that will execute inside a Docker container via a remote execution environment.
These toolchain configs include:
- C/C++ CROSSTOOL file,
- BUILD file with toolchain rules, and
- wrapper scripts.
rbe_configs_gen is a CLI tool written in Go that can be used to generate toolchain configs for a given combination of Bazel release and docker image. The output of the tool are toolchain configs in one or more of the following formats:
- Tarball
- Config files copied directly to a local directory
rbe_configs_gen requires docker to be installed locally and internet access to work.
Config users are recommended to use the CLI tool to generate and self host their own configs. Pre-generated configs will be provided for new releases of Bazel & the RBE Ubuntu 16.04 without any SLOs. See Pre-generated Configs section below for details.
The rest of this section describes how to use the rbe_configs_gen tool.
Use the official Golang docker image to build the rbe_configs_gen binary using Go 1.16. This avoids having to install the Go toolchain locally but requires docker.
- Clone this repository and set it as the working directory:
$ git clone https://github.com/bazelbuild/bazel-toolchains.git
$ cd bazel-toolchains
- Run the following command:
$ docker run --rm -v $PWD:/srcdir -w /srcdir golang:1.16 go build -o rbe_configs_gen ./cmd/rbe_configs_gen/rbe_configs_gen.go
- Run
rbe_configs_gen
as follows to see the flags it accepts:
$ ./rbe_configs_gen --help
-
Install Go for your platform if necessary. Tested to work with Go 1.16.
-
Clone this repository
$ git clone https://github.com/bazelbuild/bazel-toolchains.git
$ cd bazel-toolchains
- Build the rbe_configs_gen executable
# Use -o rbe_configs_gen.exe on Windows
$ go build -o rbe_configs_gen ./cmd/rbe_configs_gen/rbe_configs_gen.go
- Run
rbe_configs_gen
as follows to see the flags it accepts:
# On Linux
$ ./rbe_configs_gen --help
# On Windows
$ rbe_configs_gen.exe
If you'd like to generate toolchain configs for the latest available Bazel release and the toolchain container l.gcr.io/google/rbe-ubuntu16-04:latest and produce a tarball with the generated configs run:
$ ./rbe_configs_gen \
--toolchain_container=l.gcr.io/google/rbe-ubuntu16-04:latest \
--output_tarball=rbe_default.tar \
--exec_os=linux \
--target_os=linux
The exec_os
and target_os
correspond to the Bazel
execution & target platforms
respectively.
You should see a tarball file rbe_default.tar
locally containing the generated configs.
If you'd like to generate toolchain configs for a specific Bazel release, e.g., Bazel 4.0.0 (tested
for versions >= 3.7.2) and the toolchain container l.gcr.io/google/rbe-ubuntu16-04:latest and
copy the generated configs to path configs/path
relative to a source repository at
/path/to/source/repo
run:
$ ./rbe_configs_gen \
--bazel_version=4.0.0 \
--toolchain_container=l.gcr.io/google/rbe-ubuntu16-04:latest \
--output_src_root=/path/to/source/repo \
--output_config_path=configs/path \
--exec_os=linux \
--target_os=linux
/path/to/source/repo
should be the directory containing a Bazel WORKSPACE
file. The toolchain
configs will be extracted to /path/to/source/repo/configs/path
.
The exec_os
and target_os
correspond to the Bazel
execution & target platforms
respectively.
Copy/import a .bazelrc
file from here.
Pick the file that has the highest Bazel version in the filename that's less than or equal to the
Bazel version you're using.
If you copied the generated configs to the source
repository where the rest of your code lives, and assuming the configs were copied to the path
configs/path
(i.e., the value specified to the flag --output_config_path
when running
rbe_configs_gen
) relative to the directory containing the Bazel WORKSPACE
file, all you need to
do is replace all occurences of @rbe_default//
in your .bazelrc
file with //configs/path
.
If you extract the contents of a
generated toolchain configs tarball into the root of
a Github repository e.g. github.com/example/configs-repo
where this repository hosting the configs
is different from the source repository where you'd like to use the configs, include the following
in your WORKSPACE
:
load("@bazel_tools//tools/build_defs/repo:git.bzl", "git_repository")
git_repository(
name = "rbe_default",
# Replace this with the actual commit id of the Github repo you'd like to pin to.
commit = "471da0273050b88d77529484ff89741ff586f9f5",
remote = "https://github.com/example/configs-repo.git",
)
Then, assuming you've upload the toolchain configs tarball to a remote location available at the
URL https://example.com/rbe-default.tar
, include the following in your WORKSPACE
file:
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
http_archive(
name = "rbe_default",
sha256 = "<replace this with the 64 character sha256 digest of the configs tarball>",
urls = ["https://example.com/rbe-default.tar"],
)
Certain remote execution backends support custom options such as selecting the VM machine type
remote actions run on, configuring certain docker properties if the remote actions are executed in
docker containers such as network access, privileged execution, allocated memory, etc. Bazel passes
on any property specified to the exec_properties
attribute to a
platform definition to the
underlying remote execution system.
If you're using RBE, continue reading to see how to specify custom execution properties.
First, in your WORKSPACE
file, import the latest commit of this repository (replace the commit ID
and sha256 digest with latest commit if necessary):
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
http_archive(
name = "bazel_toolchains",
urls = ["https://github.com/bazelbuild/bazel-toolchains/archive/dac71231098d891e5c4b74a2078fe9343feef510.tar.gz"],
strip_prefix = "bazel-toolchains-dac71231098d891e5c4b74a2078fe9343feef510",
sha256 = "56d5370eb99559b4c74f334f81bc8a298f728bd16d5a4333c865c2ad10fae3bc",
)
load("@bazel_toolchains//repositories:repositories.bzl", bazel_toolchains_repositories = "repositories")
bazel_toolchains_repositories()
Then declare a custom platform in a BUILD
file. For now, let's assume this is the BUILD
file at
the root of your source repository (i.e., the BUILD
file & WORKSPACE
file are in the same
directory):
load("@bazel_toolchains//rules/exec_properties:exec_properties.bzl", "create_rbe_exec_properties_dict")
platform(
name = "custom_platform",
# Inherit from the platform target generated by 'rbe_configs_gen' assuming the generated configs
# were imported as a Bazel external repository named 'rbe_default'. If you extracted the
# generated configs elsewhere in your source repository, replace the following with the label
# to the 'platform' target in the generated configs.
parents = ["@rbe_default//config:platform"],
# Example custom execution property instructing RBE to use e2-standard-2 GCE VMs.
exec_properties = create_rbe_exec_properties_dict(
gce_machine_type = "e2-standard-2",
),
)
See here
for a list of parameters accepted by create_rbe_exec_properties_dict
.
Finally, in your .bazelrc
file, replace all options specifying a platform target with
the above custom platform target instead. So for example, if your .bazelrc
previously looked like
...
build:remote --extra_execution_platforms=@rbe_default//config:platform
build:remote --host_platform=@rbe_default//config:platform
build:remote --platforms=@rbe_default//config:platform
...
It should now look like
build:remote --extra_execution_platforms=//:custom_platform
build:remote --host_platform=//:custom_platform
build:remote --platforms=//:custom_platform
Pre-generated configs tarballs will be generated for every Bazel release starting with 4.0.0 & the latest available Ubuntu 16.04 Clang + JDK container and uploaded to GCS.
IMPORTANT: Ensure you read & agree with the terms of the LICENSE
file included in the
configs tarball before using pre-generated configs.
Basically, never depend directly on any of the URLs mentioned below to download toolchain configs in
production because they may break without warning. Pre-generated configs are only provided as a
convenience for experimenting with configuring Bazel for remote builds. Further, there are no
guarantees on how long after a new release of Bazel or the Ubuntu 16.04 container mentioned above
the corresponding pre-generated configs will be available. It's strongly recommended to generate and
host your own toolchain configs by running the rbe_config_gen
tool and test the functionality and
correctness of the configs yourself before using them in production. Alternatively, you could also
copy pre-generated configs and host it in a location you control after verifying correctness before
using them in production.
See here for instructions on how to initialize your .bazelrc
file.
- Examine the contents of the JSON manifest of the latest configs.
$ curl https://storage.googleapis.com/rbe-toolchain/bazel-configs/rbe-ubuntu1604/latest/manifest.json
{
"bazel_version": "4.0.0",
"toolchain_container": "l.gcr.io/google/rbe-ubuntu16-04:latest",
"image_digest": "f6568d8168b14aafd1b707019927a63c2d37113a03bcee188218f99bd0327ea1",
"exec_os": "Linux",
"configs_tarball_digest": "c0d428774cbe70d477e1d07581d863f8dbff4ba6a66d20502d7118354a814bea",
"upload_time": "2021-02-18T06:02:32.997892223-08:00"
}
- The manifest indicates the configs are for Bazel 4.0.0, generated for the container
l.gcr.io/google/rbe-ubuntu16-04@sha256:f6568d8168b14aafd1b707019927a63c2d37113a03bcee188218f99bd0327ea1
and the sha256 digest of the uploaded configs tarball isc0d428774cbe70d477e1d07581d863f8dbff4ba6a66d20502d7118354a814bea
. To use these configs, add the following to your BazelWORKSPACE
file:
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
http_archive(
name = "rbe_default",
# Change the sha256 digest to the value of the `configs_tarball_digest` in the manifest you
# got when you ran the curl command above.
sha256 = "c0d428774cbe70d477e1d07581d863f8dbff4ba6a66d20502d7118354a814bea",
urls = ["https://storage.googleapis.com/rbe-toolchain/bazel-configs/rbe-ubuntu1604/latest/rbe_default.tar"],
)
-
Say you'd like to use configs for Bazel 4.0.0 specifically.
-
Check if a manifest exists for the Bazel version you're interested in (version should be >= 4.0.0).
# Replace "bazel_4.0.0" in the URL below with whatever "bazel_<version>" you'd like to you.
$ curl https://storage.googleapis.com/rbe-toolchain/bazel-configs/bazel_4.0.0/rbe-ubuntu1604/latest/manifest.json
{
"bazel_version": "4.0.0",
"toolchain_container": "l.gcr.io/google/rbe-ubuntu16-04:latest",
"image_digest": "f6568d8168b14aafd1b707019927a63c2d37113a03bcee188218f99bd0327ea1",
"exec_os": "Linux",
"configs_tarball_digest": "c0d428774cbe70d477e1d07581d863f8dbff4ba6a66d20502d7118354a814bea",
"upload_time": "2021-02-18T06:02:32.997892223-08:00"
}
- The manifest confirms the configs are for Bazel 4.0.0, generated for the container
l.gcr.io/google/rbe-ubuntu16-04@sha256:f6568d8168b14aafd1b707019927a63c2d37113a03bcee188218f99bd0327ea1
and the sha256 digest of the uploaded configs tarball isc0d428774cbe70d477e1d07581d863f8dbff4ba6a66d20502d7118354a814bea
. To use these configs, add the following to your BazelWORKSPACE
file:
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
http_archive(
name = "rbe_default",
# Change the sha256 digest to the value of the `configs_tarball_digest` in the manifest you
# got when you ran the curl command above.
sha256 = "c0d428774cbe70d477e1d07581d863f8dbff4ba6a66d20502d7118354a814bea",
# Change "bazel_4.0.0" in the URL below with whatever "bazel_<version>" you downloaded the
# manifest for in the previous step.
urls = ["https://storage.googleapis.com/rbe-toolchain/bazel-configs/bazel_4.0.0/rbe-ubuntu1604/latest/rbe_default.tar"],
)
The rbe_autoconfig Bazel repository rule used to generate & use toolchain configs has been deprecated with release v4.0.0 of this repository being the last release that supports rbe_autoconfig. Release v4.0.0 supports Bazel versions up to 4.0.0.