I've a monorepo that contains a set of Python AWS lambdas and I'm using Bazel for building and packaging the lambdas. I'm now trying to use Bazel to create a zip file that follows the expected AWS Lambdas packaging and that I can upload to Lambda. Wondering what's the best way to do this with Bazel?
Below are a few different things I've tried thus far:
Attempt 1: py_binary
BUILD.bazel
py_binary(
name = "main_binary",
srcs = glob(["*.py"]),
main = "main.py",
visibility = ["//appcode/api/transaction_details:__subpackages__"],
deps = [
requirement("Faker"),
],
)
Problem:
This generates the following:
Lambda expects the handler to be in the format of lambda_function.lambda_handler. Since main_binary is an executable vs. a python file, it doesn't expose the actual handler method and the lambda blows up because it can't find it. I tried updating the handler configuration to simply point to the main_binary but it blows up because it expects two arguments(i.e. lambda_function.lambda_handler).
Attempt 2: py_library + pkg_zip
BUILD.bazel
py_library(
name = "main",
srcs = glob(["*.py"]),
visibility = ["//appcode/api/transaction_details:__subpackages__"],
deps = [
requirement("Faker"),
],
)
pkg_zip(
name = "main_zip",
srcs =["//appcode/api/transaction_details/src:main" ],
)
Problem:
This generates a zip file with:
__init__.pyThe zip file now includes the main.py but none of its runtime dependencies. Thus the lambda blows up because it can't find Faker.
Other Attempts:
I've also tried using the --build_python_zip flag as well as the @bazel_tools//tools/zip:zipper with a generic rule but they both lead to similar outcomes as the two previous attempts.
Below are the changes I made to the previous answer to generate the lambda zip. Thanks @jvolkman for the original suggestion.
project/BUILD.bazel: Added rule to generate requirements_lock.txt from project/requirements.txt
load("@rules_python//python:pip.bzl", "compile_pip_requirements")
compile_pip_requirements(
name = "requirements",
extra_args = ["--allow-unsafe"],
requirements_in = "requirements.txt",
requirements_txt = "requirements_lock.txt",
)
project/WORKSPACE.bazel: swap pip_install with pip_parse
workspace(name = "mdc-eligibility")
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
http_archive(
name = "rules_python",
sha256 = "9fcf91dbcc31fde6d1edb15f117246d912c33c36f44cf681976bd886538deba6",
strip_prefix = "rules_python-0.8.0",
url = "https://github.com/bazelbuild/rules_python/archive/refs/tags/0.8.0.tar.gz",
)
load("@rules_python//python:repositories.bzl", "python_register_toolchains")
python_register_toolchains(
name = "python3_9",
python_version = "3.9",
)
load("@rules_python//python:pip.bzl", "pip_parse")
load("@python3_9//:defs.bzl", "interpreter")
pip_parse(
name = "mndc-eligibility-deps",
requirements_lock = "//:requirements_lock.txt",
python_interpreter_target = interpreter,
quiet = False
)
load("@mndc-eligibility-deps//:requirements.bzl", "install_deps")
install_deps()
project/build_rules/lambda_packaging/lambda.bzl: Modified custom rule provided by @jvolkman to include source code in the resulting zip code.
def contains(pattern):
return "contains:" + pattern
def startswith(pattern):
return "startswith:" + pattern
def endswith(pattern):
return "endswith:" + pattern
def _is_ignored(path, patterns):
for p in patterns:
if p.startswith("contains:"):
if p[len("contains:"):] in path:
return True
elif p.startswith("startswith:"):
if path.startswith(p[len("startswith:"):]):
return True
elif p.startswith("endswith:"):
if path.endswith(p[len("endswith:"):]):
return True
else:
fail("Invalid pattern: " + p)
return False
def _short_path(file_):
# Remove prefixes for external and generated files.
# E.g.,
# ../py_deps_pypi__pydantic/pydantic/__init__.py -> pydantic/__init__.py
short_path = file_.short_path
if short_path.startswith("../"):
second_slash = short_path.index("/", 3)
short_path = short_path[second_slash + 1:]
return short_path
# steven chambers
def _py_lambda_zip_impl(ctx):
deps = ctx.attr.target[DefaultInfo].default_runfiles.files
f = ctx.outputs.output
args = []
for dep in deps.to_list():
short_path = _short_path(dep)
# Skip ignored patterns
if _is_ignored(short_path, ctx.attr.ignore):
continue
args.append(short_path + "=" + dep.path)
# MODIFICATION: Added source files to the map of files to zip
source_files = ctx.attr.target[DefaultInfo].files
for source_file in source_files.to_list():
args.append(source_file.basename+"="+source_file.path)
ctx.actions.run(
outputs = [f],
inputs = deps,
executable = ctx.executable._zipper,
arguments = ["cC", f.path] + args,
progress_message = "Creating archive...",
mnemonic = "archiver",
)
out = depset(direct = [f])
return [
DefaultInfo(
files = out,
),
OutputGroupInfo(
all_files = out,
),
]
_py_lambda_zip = rule(
implementation = _py_lambda_zip_impl,
attrs = {
"target": attr.label(),
"ignore": attr.string_list(),
"_zipper": attr.label(
default = Label("@bazel_tools//tools/zip:zipper"),
cfg = "host",
executable = True,
),
"output": attr.output(),
},
executable = False,
test = False,
)
def py_lambda_zip(name, target, ignore, **kwargs):
_py_lambda_zip(
name = name,
target = target,
ignore = ignore,
output = name + ".zip",
**kwargs
)
project/appcode/api/transaction_details/src/BUILD.bazel: Used custom py_lambda_zip rule to zip up py_library
load("@mndc-eligibility-deps//:requirements.bzl", "requirement")
load("@python3_9//:defs.bzl", "interpreter")
load("//build_rules/lambda_packaging:lambda.bzl", "contains", "endswith", "py_lambda_zip", "startswith")
py_library(
name = "main",
srcs = glob(["*.py"]),
visibility = ["//appcode/api/transaction_details:__subpackages__"],
deps = [
requirement("Faker"),
],
)
py_lambda_zip(
name = "lambda_archive",
ignore = [
contains("/__pycache__/"),
endswith(".pyc"),
endswith(".pyo"),
# Ignore boto since it's provided by Lambda.
startswith("boto3/"),
startswith("botocore/"),
# With the move to hermetic toolchains, the zip gets a lib/ directory containing the
# python runtime. We don't need that.
startswith("lib/"),
],
target = ":main",
)