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Building Envoy with Bazel

Installing Bazelisk as Bazel

It is recommended to use Bazelisk installed as bazel, to avoid Bazel compatibility issues. On Linux, run the following commands:

sudo wget -O /usr/local/bin/bazel https://github.com/bazelbuild/bazelisk/releases/download/v0.0.8/bazelisk-linux-amd64
sudo chmod +x /usr/local/bin/bazel

On macOS, run the follwing command:

brew install bazelbuild/tap/bazelisk

If you're building from an revision of Envoy prior to August 2019, which doesn't contains a .bazelversion file, run ci/run_envoy_docker.sh "bazel version" to find the right version of Bazel and set the version to USE_BAZEL_VERSION environment variable to build.

Production environments

To build Envoy with Bazel in a production environment, where the Envoy dependencies are typically independently sourced, the following steps should be followed:

  1. Configure, build and/or install the Envoy dependencies.
  2. bazel build -c opt //source/exe:envoy-static from the repository root.

Quick start Bazel build for developers

As a developer convenience, a WORKSPACE and rules for building a recent version of the various Envoy dependencies are provided. These are provided as is, they are only suitable for development and testing purposes. The specific versions of the Envoy dependencies used in this build may not be up-to-date with the latest security patches. See this doc for how to update or override dependencies.

  1. Install external dependencies libtool, cmake, ninja, realpath and curl libraries separately. On Ubuntu, run the following command:

    sudo apt-get install \
   libtool \
   cmake \
   automake \
   autoconf \
   make \
   ninja-build \
   curl \
   unzip \
   virtualenv

    On Fedora (maybe also other red hat distros), run the following:

    dnf install cmake libtool libstdc++ libstdc++-static libatomic ninja-build lld patch aspell-en

    On Linux, we recommend using the prebuilt Clang+LLVM package from LLVM official site. Extract the tar.xz and run the following:

    bazel/setup_clang.sh <PATH_TO_EXTRACTED_CLANG_LLVM>

    This will setup a clang.bazelrc file in Envoy source root. If you want to make clang as default, run the following:

    echo "build --config=clang" >> user.bazelrc

    On macOS, you'll need to install several dependencies. This can be accomplished via Homebrew:

    brew install coreutils wget cmake libtool go bazel automake ninja clang-format autoconf aspell

    notes: coreutils is used for realpath, gmd5sum and gsha256sum

    Xcode is also required to build Envoy on macOS. Envoy compiles and passes tests with the version of clang installed by Xcode 11.1: Apple clang version 11.0.0 (clang-1100.0.33.8).

    In order for bazel to be aware of the tools installed by brew, the PATH variable must be set for bazel builds. This can be accomplished by setting this in your user.bazelrc file:

    build --action_env=PATH="/usr/local/bin:/opt/local/bin:/usr/bin:/bin"

    Alternatively, you can pass --action_env on the command line when running bazel build/bazel test.

    Having the binutils keg installed in Brew is known to cause issues due to putting an incompatible version of ar on the PATH, so if you run into issues building third party code like luajit consider uninstalling binutils.

  2. Install Golang on your machine. This is required as part of building BoringSSL and also for Buildifer which is used for formatting bazel BUILD files.

  3. go get -u github.com/bazelbuild/buildtools/buildifier to install buildifier. You may need to set BUILDIFIER_BIN to $GOPATH/bin/buildifier in your shell for buildifier to work.

  4. go get -u github.com/bazelbuild/buildtools/buildozer to install buildozer. You may need to set BUILDOZER_BIN to $GOPATH/bin/buildozer in your shell for buildozer to work.

  5. bazel build //source/exe:envoy-static from the Envoy source directory.

Building Envoy with the CI Docker image

Envoy can also be built with the Docker image used for CI, by installing Docker and executing:

./ci/run_envoy_docker.sh './ci/do_ci.sh bazel.dev'

See also the documentation for developer use of the CI Docker image.

Building Envoy with Remote Execution

Envoy can also be built with Bazel Remote Execution, part of the CI is running with the hosted GCP RBE service.

To build Envoy with a remote build services, run Bazel with your remote build service flags and with --config=remote-clang. For example the following command runs build with the GCP RBE service used in CI:

bazel build //source/exe:envoy-static --config=remote-clang \
    --remote_cache=grpcs://remotebuildexecution.googleapis.com \
    --remote_executor=grpcs://remotebuildexecution.googleapis.com \
    --remote_instance_name=projects/envoy-ci/instances/default_instance

Change the value of --remote_cache, --remote_executor and --remote_instance_name for your remote build services. Tests can be run in remote execution too.

Note: Currently the test run configuration in .bazelrc doesn't download test binaries and test logs, to override the behavior set --experimental_remote_download_outputs accordingly.

Building Envoy with Docker sandbox

Building Envoy with Docker sandbox uses the same Docker image used in CI with fixed C++ toolchain configuration. It produces more consistent output which is not depending on your local C++ toolchain. It can also help debugging issues with RBE. To build Envoy with Docker sandbox:

bazel build //source/exe:envoy-static --config=docker-clang

Tests can be run in docker sandbox too. Note that the network environment, such as IPv6, may be different in the docker sandbox so you may want set different options. See below to configure test IP versions.

Linking against libc++ on Linux

To link Envoy against libc++, follow the quick start to setup Clang+LLVM and run:

bazel build --config=libc++ //source/exe:envoy-static

Or use our configuration with Remote Execution or Docker sandbox, pass --config=remote-clang-libc++ or --config=docker-clang-libc++ respectively.

If you want to make libc++ as default, add a line build --config=libc++ to the user.bazelrc file in Envoy source root.

Using a compiler toolchain in a non-standard location

By setting the CC and LD_LIBRARY_PATH in the environment that Bazel executes from as appropriate, an arbitrary compiler toolchain and standard library location can be specified. One slight caveat is that (at the time of writing), Bazel expects the binutils in $(dirname $CC) to be unprefixed, e.g. as instead of x86_64-linux-gnu-as.

Note: this configuration currently doesn't work with Remote Execution or Docker sandbox, you have to generate a custom toolchains configuration for them. See bazelbuild/bazel-toolchains for more details.

Supported compiler versions

We now require Clang >= 5.0 due to known issues with std::string thread safety and C++14 support. GCC >= 7 is also known to work. Currently the CI is running with Clang 9.

Clang STL debug symbols

By default Clang drops some debug symbols that are required for pretty printing to work correctly. More information can be found here. The easy solution is to set --copt=-fno-limit-debug-info on the CLI or in your .bazelrc file.

Testing Envoy with Bazel

All the Envoy tests can be built and run with:

bazel test //test/...

An individual test target can be run with a more specific Bazel label, e.g. to build and run only the units tests in test/common/http/async_client_impl_test.cc:

bazel test //test/common/http:async_client_impl_test

To observe more verbose test output:

bazel test --test_output=streamed //test/common/http:async_client_impl_test

It's also possible to pass into an Envoy test additional command-line args via --test_arg. For example, for extremely verbose test debugging:

bazel test --test_output=streamed //test/common/http:async_client_impl_test --test_arg="-l trace"

By default, testing exercises both IPv4 and IPv6 address connections. In IPv4 or IPv6 only environments, set the environment variable ENVOY_IP_TEST_VERSIONS to "v4only" or "v6only", respectively.

bazel test //test/... --test_env=ENVOY_IP_TEST_VERSIONS=v4only
bazel test //test/... --test_env=ENVOY_IP_TEST_VERSIONS=v6only

By default, tests are run with the gperftools heap checker enabled in "normal" mode to detect leaks. For other mode options, see the gperftools heap checker documentation. To disable the heap checker or change the mode, set the HEAPCHECK environment variable:

# Disables the heap checker
bazel test //test/... --test_env=HEAPCHECK=
# Changes the heap checker to "minimal" mode
bazel test //test/... --test_env=HEAPCHECK=minimal

If you see a leak detected, by default the reported offsets will require addr2line interpretation. You can run under --config=clang-asan to have this automatically applied.

Bazel will by default cache successful test results. To force it to rerun tests:

bazel test //test/common/http:async_client_impl_test --cache_test_results=no

Bazel will by default run all tests inside a sandbox, which disallows access to the local filesystem. If you need to break out of the sandbox (for example to run under a local script or tool with --run_under), you can run the test with --strategy=TestRunner=local, e.g.:

bazel test //test/common/http:async_client_impl_test --strategy=TestRunner=local --run_under=/some/path/foobar.sh

Stack trace symbol resolution

Envoy can produce backtraces on demand and from assertions and other fatal actions like segfaults. Where supported, stack traces will contain resolved symbols, though not include line numbers. On systems where absl::Symbolization is not supported, the stack traces written in the log or to stderr contain addresses rather than resolved symbols. If the symbols were resolved, the address is also included at the end of the line.

The tools/stack_decode.py script exists to process the output and do additional symbol resolution including file names and line numbers. It requires the addr2line program be installed and in your path. Any log lines not relevant to the backtrace capability are passed through the script unchanged (it acts like a filter). File and line information is appended to the stack trace lines.

The script runs in one of two modes. To process log input from stdin, pass -s as the first argument, followed by the executable file path. You can postprocess a log or pipe the output of an Envoy process. If you do not specify the -s argument it runs the arguments as a child process. This enables you to run a test with backtrace post processing. Bazel sandboxing must be disabled by specifying local execution. Example command line with run_under:

bazel test -c dbg //test/server:backtrace_test
--run_under=`pwd`/tools/stack_decode.py --strategy=TestRunner=local
--cache_test_results=no --test_output=all

Example using input on stdin:

bazel test -c dbg //test/server:backtrace_test --cache_test_results=no --test_output=streamed |& tools/stack_decode.py -s bazel-bin/test/server/backtrace_test

You will need to use either a dbg build type or the opt build type to get file and line symbol information in the binaries.

By default main.cc will install signal handlers to print backtraces at the location where a fatal signal occurred. The signal handler will re-raise the fatal signal with the default handler so a core file will still be dumped after the stack trace is logged. To inhibit this behavior use --define=signal_trace=disabled on the Bazel command line. No signal handlers will be installed.

Running a single Bazel test under GDB

bazel build -c dbg //test/common/http:async_client_impl_test
gdb bazel-bin/test/common/http/async_client_impl_test

Without the -c dbg Bazel option at the end of the command line the test binaries will not include debugging symbols and GDB will not be very useful.

Running Bazel tests requiring privileges

Some tests may require privileges (e.g. CAP_NET_ADMIN) in order to execute. One option is to run them with elevated privileges, e.g. sudo test. However, that may not always be possible, particularly if the test needs to run in a CI pipeline. tools/bazel-test-docker.sh may be used in such situations to run the tests in a privileged docker container.

The script works by wrapping the test execution in the current repository's circle ci build container, then executing it either locally or on a remote docker container. In both cases, the container runs with the --privileged flag, allowing it to execute operations which would otherwise be restricted.

The command line format is: tools/bazel-test-docker.sh <bazel-test-target> [optional-flags-to-bazel]

The script uses two optional environment variables to control its behaviour:

  • RUN_REMOTE=<yes|no>: chooses whether to run on a remote docker server.
  • LOCAL_MOUNT=<yes|no>: copy/mount local libraries onto the docker container.

Use RUN_REMOTE=yes when you don't want to run against your local docker instance. Note that you will need to override a few environment variables to set up the remote docker. The list of variables can be found in the Documentation.

Use LOCAL_MOUNT=yes when you are not building with the Envoy build container. This will ensure that the libraries against which the tests dynamically link will be available and of the correct version.

Examples

Running the http integration test in a privileged container:

tools/bazel-test-docker.sh  //test/integration:integration_test --jobs=4 -c dbg

Running the http integration test compiled locally against a privileged remote container:

setup_remote_docker_variables
RUN_REMOTE=yes MOUNT_LOCAL=yes tools/bazel-test-docker.sh  //test/integration:integration_test \
  --jobs=4 -c dbg

Additional Envoy build and test options

In general, there are 3 compilation modes that Bazel supports:

  • fastbuild: -O0, aimed at developer speed (default).
  • opt: -O2 -DNDEBUG -ggdb3, for production builds and performance benchmarking.
  • dbg: -O0 -ggdb3, no optimization and debug symbols.

You can use the -c <compilation_mode> flag to control this, e.g.

bazel build -c opt //source/exe:envoy-static

To override the compilation mode and optimize the build for binary size, you can use the sizeopt configuration:

bazel build //source/exe:envoy-static --config=sizeopt

Sanitizers

To build and run tests with the gcc compiler's address sanitizer (ASAN) and undefined behavior (UBSAN) sanitizer enabled:

bazel test -c dbg --config=asan //test/...

The ASAN failure stack traces include line numbers as a result of running ASAN with a dbg build above. If the stack trace is not symbolized, try setting the ASAN_SYMBOLIZER_PATH environment variable to point to the llvm-symbolizer binary (or make sure the llvm-symbolizer is in your $PATH).

If you have clang-5.0 or newer, additional checks are provided with:

bazel test -c dbg --config=clang-asan //test/...

Similarly, for thread sanitizer (TSAN) testing:

bazel test -c dbg --config=clang-tsan //test/...

To run the sanitizers on OS X, prefix macos- to the config option, e.g.:

bazel test -c dbg --config=macos-asan //test/...

Log Verbosity

Log verbosity is controlled at runtime in all builds.

Disabling optional features

The following optional features can be disabled on the Bazel build command-line:

  • Hot restart with --define hot_restart=disabled
  • Google C++ gRPC client with --define google_grpc=disabled
  • Backtracing on signals with --define signal_trace=disabled
  • Active stream state dump on signals with --define signal_trace=disabled or --define disable_object_dump_on_signal_trace=disabled
  • tcmalloc with --define tcmalloc=disabled
  • deprecated features with --define deprecated_features=disabled

Enabling optional features

The following optional features can be enabled on the Bazel build command-line:

  • Exported symbols during linking with --define exported_symbols=enabled. This is useful in cases where you have a lua script that loads shared object libraries, such as those installed via luarocks.
  • Perf annotation with --define perf_annotation=enabled (see source/common/common/perf_annotation.h for details).
  • BoringSSL can be built in a FIPS-compliant mode with --define boringssl=fips (see FIPS 140-2 for details).
  • ASSERT() can be configured to log failures and increment a stat counter in a release build with --define log_debug_assert_in_release=enabled. The default behavior is to compile debug assertions out of release builds so that the condition is not evaluated. This option has no effect in debug builds.
  • memory-debugging (scribbling over memory after allocation and before freeing) with --define tcmalloc=debug. Note this option cannot be used with FIPS-compliant mode BoringSSL.
  • Default path normalization with --define path_normalization_by_default=true. Note this still could be disable by explicit xDS config.
  • Manual stamping via VersionInfo with --define manual_stamp=manual_stamp. This is needed if the version_info_lib is compiled via a non-binary bazel rules, e.g envoy_cc_library. Otherwise, the linker will fail to resolve symbols that are included via the linktamp rule, which is only available to binary targets. This is being tracked as a feature in: envoyproxy#6859.

Disabling extensions

Envoy uses a modular build which allows extensions to be removed if they are not needed or desired. Extensions that can be removed are contained in extensions_build_config.bzl. Use the following procedure to customize the extensions for your build:

  • The Envoy build assumes that a Bazel repository named @envoy_build_config exists which contains the file @envoy_build_config//:extensions_build_config.bzl. In the default build, a synthetic repository is created containing extensions_build_config.bzl. Thus, the default build has all extensions.
  • Start by creating a new Bazel workspace somewhere in the filesystem that your build can access. This workspace should contain:
    • Empty WORKSPACE file.
    • Empty BUILD file.
    • A copy of extensions_build_config.bzl.
    • Comment out any extensions that you don't want to build in your file copy.

To have your local build use your overridden configuration repository there are two options:

  1. Use the --override_repository CLI option to override the @envoy_build_config repo.
  2. Use the following snippet in your WORKSPACE before you load the Envoy repository. E.g.,
workspace(name = "envoy")

local_repository(
    name = "envoy_build_config",
    # Relative paths are also supported.
    path = "/somewhere/on/filesystem/envoy_build_config",
)

local_repository(
    name = "envoy",
    # Relative paths are also supported.
    path = "/somewhere/on/filesystem/envoy",
)

...

Release builds

Release builds should be built in opt mode, processed with strip and have a .note.gnu.build-id section with the Git SHA1 at which the build took place. They should also ignore any local .bazelrc for reproducibility. This can be achieved with:

bazel --bazelrc=/dev/null build -c opt //source/exe:envoy-static.stripped

One caveat to note is that the Git SHA1 is truncated to 16 bytes today as a result of the workaround in place for bazelbuild/bazel#2805.

Coverage builds

To generate coverage results, make sure you are using a clang toolchain and have llvm-cov and llvm-profdata in your PATH. Then run:

test/run_envoy_bazel_coverage.sh

The summary results are printed to the standard output and the full coverage report is available in generated/coverage/coverage.html.

Coverage for every PR is available in Circle in the "artifacts" tab of the coverage job. You will need to navigate down and open "coverage.html" but then you can navigate per normal. NOTE: We have seen some issues with seeing the artifacts tab. If you can't see it, log out of Circle, and then log back in and it should start working.

The latest coverage report for master is available here.

It's also possible to specialize the coverage build to a specified test or test dir. This is useful when doing things like exploring the coverage of a fuzzer over its corpus. This can be done by passing coverage targets as the command-line arguments and using the VALIDATE_COVERAGE environment variable, e.g.:

VALIDATE_COVERAGE=false test/run_envoy_bazel_coverage.sh //test/common/common:base64_fuzz_test

Cleaning the build and test artifacts

bazel clean will nuke all the build/test artifacts from the Bazel cache for Envoy proper. To remove the artifacts for the external dependencies run bazel clean --expunge.

If something goes really wrong and none of the above work to resolve a stale build issue, you can always remove your Bazel cache completely. It is likely located in ~/.cache/bazel.

Adding or maintaining Envoy build rules

See the developer guide for writing Envoy Bazel rules.

Bazel performance on (virtual) machines with low resources

If the (virtual) machine that is performing the build is low on memory or CPU resources, you can override Bazel's default job parallelism determination with --jobs=N to restrict the build to at most N simultaneous jobs, e.g.:

bazel build --jobs=2 //source/exe:envoy-static

Debugging the Bazel build

When trying to understand what Bazel is doing, the -s and --explain options are useful. To have Bazel provide verbose output on which commands it is executing:

bazel build -s //source/exe:envoy-static

To have Bazel emit to a text file the rationale for rebuilding a target:

bazel build --explain=file.txt //source/exe:envoy-static

To get more verbose explanations:

bazel build --explain=file.txt --verbose_explanations //source/exe:envoy-static

Resolving paths in bazel build output

Sometimes it's useful to see real system paths in bazel error message output (vs. symbolic links). tools/path_fix.sh is provided to help with this. See the comments in that file.

Compilation database

Run tools/gen_compilation_database.py to generate a JSON Compilation Database. This could be used with any tools (e.g. clang-tidy) compatible with the format.

The compilation database could also be used to setup editors with cross reference, code completion. For example, you can use You Complete Me or cquery with supported editors.

Running clang-format without docker

The easiest way to run the clang-format check/fix commands is to run them via docker, which helps ensure the right toolchain is set up. However you may prefer to run clang-format scripts on your workstation directly:

  • It's possible there is a speed advantage
  • Docker itself can sometimes go awry and you then have to deal with that
  • Type-ahead doesn't always work when waiting running a command through docker

To run the tools directly, you must install the correct version of clang. This may change over time, check the version of clang in the docker image. You must also have 'buildifier' installed from the bazel distribution.

Edit the paths shown here to reflect the installation locations on your system:

export CLANG_FORMAT="$HOME/ext/clang+llvm-9.0.0-x86_64-linux-gnu-ubuntu-16.04/bin/clang-format"
export BUILDIFIER_BIN="/usr/bin/buildifier"

Once this is set up, you can run clang-format without docker:

./tools/check_format.py check
./tools/check_spelling.sh check
./tools/check_format.py fix
./tools/check_spelling.sh fix

Advanced caching setup

Setting up an HTTP cache for Bazel output helps optimize Bazel performance and resource usage when using multiple compilation modes or multiple trees.

Setup local cache

You may use any Remote Caching backend as an alternative to this.

This requires Go 1.11+, follow the instructions to install if you don't have one. To start the cache, run the following from the root of the Envoy repository (or anywhere else that the Go toolchain can find the necessary dependencies):

go run github.com/buchgr/bazel-remote --dir ${HOME}/bazel_cache --host 127.0.0.1 --port 28080 --max_size 64

See Bazel remote cache for more information on the parameters. The command above will setup a maximum 64 GiB cache at ~/bazel_cache on port 28080. You might want to setup a larger cache if you run ASAN builds.

NOTE: Using docker to run remote cache server described in remote cache docs will likely have slower cache performance on macOS due to slow disk performance on Docker for Mac.

Adding the following parameter to Bazel everytime or persist them in .bazelrc.

--remote_http_cache=http://127.0.0.1:28080/