[drake_bazel_external] Port to use MODULE.bazel

drake_bazel_external/.bazelrc

@@ -1,9 +1,5 @@
 # SPDX-License-Identifier: MIT-0
 
-# Don't use bzlmod yet.
-common --enable_workspace=true
-common --enable_bzlmod=false
-
 # Default to an optimized build.
 build --compilation_mode=opt
 

drake_bazel_external/.gitignore

@@ -2,3 +2,4 @@
 
 /bazel-*
 /user.bazelrc
+/MODULE.bazel.lock

drake_bazel_external/MODULE.bazel

@@ -0,0 +1,42 @@
+# SPDX-License-Identifier: MIT-0
+
+module(name = "drake_external_examples")
+
+# Add the Bazel rules we need.
+bazel_dep(name = "rules_cc", version = "0.0.17")
+bazel_dep(name = "rules_python", version = "0.40.0")
+
+# Use the host system python.
+register_toolchains("@bazel_tools//tools/python:autodetecting_toolchain")
+
+# Here we introduce Drake as a module dependency, but note that Drake is not
+# published to any Bazel registry. Below, we'll override it with a github
+# source archive.
+bazel_dep(name = "drake")
+
+# By default, this example always uses the latest Drake master branch.
+DRAKE_COMMIT = "bzlmod-extension"
+DRAKE_CHECKSUM = ""
+
+# You can choose a specific revision of Drake to use, e.g.:
+# DRAKE_COMMIT = "be4f658487f739ba04ec079de46f9459b719636d"
+# DRAKE_CHECKSUM = "31ec8f87df3ceb6516de3c33a14c5d59ac5c003b4faf93ac526877d2e150b394"
+#
+# You can also use DRAKE_COMMIT to choose a Drake release; e.g.:
+# DRAKE_COMMIT = "v0.15.0"
+# DRAKE_CHECKSUM = "... TBD ..."
+#
+# Before changing the COMMIT, temporarily uncomment the next line so that Bazel
+# displays the suggested new value for the CHECKSUM.
+# DRAKE_CHECKSUM = "0" * 64
+
+# This declares the `@drake` module as a source code archive from github.
+# See README.md for instructions to use a local path, instead.
+archive_override(
+    module_name = "drake",
+    urls = [x.format(DRAKE_COMMIT) for x in [
+        "https://github.com/jwnimmer-tri/drake/archive/{}.tar.gz",
+    ]],
+    sha256 = DRAKE_CHECKSUM,
+    strip_prefix = "drake-{}".format(DRAKE_COMMIT.lstrip("v")),
+)

drake_bazel_external/README.md

@@ -33,6 +33,15 @@ cause differences.  This is important when using tools like
 `drake::FindResource` / `pydrake.common.FindResource`.
 You may generally want to stick to using `bazel run` when able.
 
+### Using a local checkout of Drake
+
+To use Drake sources on disk instead of downloaded from github, pass the flag
+``--override_module=drake=/home/user/stuff/drake`` to bazel on the command line
+or add a line such as the following to ``user.bazelrc`` in the current directory:
+```
+build --override_module=drake=/home/user/stuff/drake
+```
+
 ## Python Versions
 
 By default, Python 3 is the Python interpreter that Drake will use when built

drake_bazel_external/apps/BUILD.bazel

@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: MIT-0
 
-load("@drake//tools/skylark:py.bzl", "py_binary", "py_test")
+load("@rules_cc//cc:defs.bzl", "cc_binary")
+load("@rules_python//python:defs.bzl", "py_binary", "py_library", "py_test")
 load("@drake//tools/skylark:pybind.bzl", "pybind_py_library")
 
 # Compile a sample application.
@@ -79,6 +80,7 @@ cc_test(
 
 pybind_py_library(
     name = "simple_adder_py",
+    cc_binary_rule = cc_binary,
     cc_so_name = "simple_adder",
     cc_srcs = ["simple_adder_py.cc"],
     cc_deps = [
@@ -88,6 +90,7 @@ pybind_py_library(
     ],
     py_deps = ["@drake//bindings/pydrake"],
     py_imports = ["."],
+    py_library_rule = py_library,
 )
 
 # Mimic the C++ test in Python to show the bindings.

private/test/file_sync_test.py

@@ -73,17 +73,13 @@
     for path in [
         ".bazelignore",
         ".bazelproject",
-        ".bazelrc",
         ".clang-format",
         ".github/ci_build_test",
         ".github/setup",
         ".github/ubuntu_setup",
-        ".gitignore",
         "BUILD.bazel",
         "CPPLINT.cfg",
         "LICENSE",
-        "WORKSPACE",
-        "apps/BUILD.bazel",
         "apps/exec.sh",
         "apps/find_resource_test.py",
         "apps/import_all_test.py",
@@ -95,7 +91,6 @@
         "apps/simple_adder_test.cc",
         "apps/simple_continuous_time_system.cc",
         "apps/simple_logging_example.py",
-        "environ.bzl",
         "setup/install_prereqs",
     ]
 ])