bazel: Add python envoy_entry_point

tools/base/entry_point.py

@@ -0,0 +1,13 @@
+import subprocess
+import sys
+
+
+def main(*args) -> int:
+    try:
+        return subprocess.run(args).returncode
+    except KeyboardInterrupt:
+        return 1
+
+
+if __name__ == "__main__":
+    sys.exit(main(*sys.argv[1:]))

tools/base/envoy_python.bzl

@@ -1,4 +1,5 @@
 load("@rules_python//python:defs.bzl", "py_binary", "py_library")
+load("@base_pip3//:requirements.bzl", base_entry_point = "entry_point")
 
 def envoy_py_test(name, package, visibility, envoy_prefix = "@envoy"):
     filepath = "$(location %s//tools/testing:base_pytest_runner.py)" % envoy_prefix
@@ -71,3 +72,44 @@ def envoy_py_binary(
 
     if test:
         envoy_py_test(name, package, visibility, envoy_prefix = envoy_prefix)
+
+def envoy_entry_point(
+        name,
+        pkg,
+        main = "//tools/base:entry_point.py",
+        entry_point = base_entry_point,
+        script = None,
+        data = None,
+        args = None):
+    """This macro provides the convenience of using an `entry_point` while
+    also being able to create a rule with associated `args` and `data`, as is
+    possible with the normal `py_binary` rule.
+
+    We may wish to remove this macro should https://github.com/bazelbuild/rules_python/issues/600
+    be resolved.
+
+    The `script` and `pkg` args are passed directly to the `entry_point`.
+
+    By default, the pip `entry_point` from `@base_pip3` is used. You can provide
+    a custom `entry_point` if eg you want to provide an `entry_point` with dev
+    requirements, or from some other requirements set.
+
+    A `py_binary` is dynamically created to wrap the `entry_point` with provided
+    `args` and `data`.
+    """
+    script = script or pkg
+    entry_point_name = "%s_entry_point" % name
+    native.alias(
+        name = entry_point_name,
+        actual = entry_point(
+            pkg = pkg,
+            script = script,
+        ),
+    )
+    py_binary(
+        name = name,
+        srcs = [main],
+        main = main,
+        args = ["$(location %s)" % entry_point_name] + args,
+        data = [entry_point_name] + data,
+    )