Deprecate and remove implicit py_binary zipapp support

[rickeylev]

The implicit zipapp support of py_binary and py_test is being deprecated and removed. It is replaced by the py_zipapp_binary and py_zipapp_test rules. There are several ways the implicit zipapp logic may be activated.

For reference, these are the two loads you're most likely to need:

load("@rules_python//python/zipapp:py_zipapp_binary.bzl", "py_zipapp_binary")
load("@rules_python//python/zipapp:py_zipapp_test.bzl", "py_zipapp_test")

The flag name you want to look for is build_python_zip.

Windows-specific note: Windows enables zipapp by default, so the absence of the flag is the same as --build_python_zip=true !

Migration guide

This guide tries to give information on how to handle all possible cases of what may need to be migrated. Most changes are small, should be transparent, and can be done incrementally.

In practice, the most likely scenario you'll need to fix is using the
--build_python_zip flag on the command line -- see the "Migrate explicit --build_python_zip" section for that case.

Disable legacy zipapp flag

Add common --build_python_zip=false --@rules_python//python/config_settings:build_python_zip=false to your .bazelrc

Windows-specific note: Windows enables zipapp by default

Migrate explicit --build_python_zip usage

TLDR: Replace --build_python_zip on the command line with a py_zipapp_binary target in a BUILD file.

Replace this:

# File: BUILD

py_binary(name="bin")

# Command line
bazel build //:bin --build_python_zip

With this:

# File: BUILD
load("@rules_python//python/zipapp:py_zipapp_binary", "py_zipapp_binary")

py_binary(name="bin")
py_zipapp_binary(name = "bin_zipapp", binary=":bin")

# Command line
bazel build //:bin_zipapp

Migrate py_binary using config_settings with py_zipapp rule

TLDR: Add py_zipapp_binary for each py_binary you want as a zipapp

Replace this:

py_binary(
  name = "bin"
  config_settings = {
    "@rules_python//python/config:build_python_zip": "true",
    "//command_line_option:build_python_zip": "true",
  },
  ...
)

With this:

load("@rules_python//python/zipapp:py_zipapp_binary", "py_zipapp_binary")

py_binary(
  name = "bin"
  ...
)

py_zipapp_binary(
  name = "bin.zipapp",
  binary = ":bin",
)

Migrate filegroup using python_zip_file output group

Replace this:

TLDR: Add py_zipapp_binary and point the filegroup to it.

py_binary(name = "bin", ...)

filegroup(
  name = "bin_zip_file",
  output_group = "python_zip_file",
  srcs = [":bin"],
)

With this:

load("@rules_python//python/zipapp:py_zipapp_binary", "py_zipapp_binary")

py_binary(name = "bin", ...)
py_zipapp_binary(name = "bin_zipapp", binary=":bin")
filegroup(
  name = "bin_zip_file",
  output_group = "python_zip_file",
  srcs = [":bin_zipapp"],
)

Migrate Starlark using python_zip_file output group

TLDR: Add py_zipapp target and use it as the input target instead.

Replace this:

# File: my_rule.bzl
def _my_rule_impl(ctx):
  zip_file = ctx.attr.binary[OutputGroupInfo]["python_zip_file"].to_list()[0]

# File: BUILD.bazel
py_binary(name="bin", ...)
my_rule(name = "mytarget", binary=":bin", ...)

With this:

# File: my_rule.bzl

def _my_rule_impl(ctx):
  zip_file = ctx.attr.binary[OutputGroupInfo]["python_zip_file"].to_list()[0]

# File: BUILD.bazel
load("@rules_python//python/zipapp:py_zipapp_binary", "py_zipapp_binary")
py_binary(name="bin", ...)
py_zipapp_binary(name = "bin_zipapp", binary=":bin")
my_rule(name = "mytarget", binary=":bin_zipapp", ...)

Migration transitions setting build_python_zip flags

TLDR: Remove the build_python_zip flags from the transition and refactor into a separate target.

Replace this:

# File: rule.bzl
my_transition = transition(
   outputs = [
      "//command_line_settings:build_python_zip",
      "@rules_python//python/config_settings:build_python_zip",
   ],
   ...
)
my_rule(cfg = my_transition, ...)

# File: BUILD
py_binary(name="bin", ...)
my_rule(target=":bin")

With this:

# File: rule.bzl
my_transition = transition(
   outputs = [],
   ...
)
my_rule(cfg = my_transition, ...)

# File: BUILD
load("@rules_python//python/zipapp:py_zipapp_binary", "py_zipapp_binary")
py_binary(name="bin", ...)
py_zipapp_binary(name="bin_zipapp", binary=":bin")
my_rule(target=":bin_zipapp")