Put the py3 toolchain in the tin

WORKSPACE

@@ -27,8 +27,18 @@ git_repository(
 load("@bazel_skylib//:workspace.bzl", "bazel_skylib_workspace")
 bazel_skylib_workspace()
 
+####################################################################################################
+# rules_python
+####################################################################################################
+
 git_repository(
     name = "rules_python",
     remote = "https://github.com/bazelbuild/rules_python.git",
     tag = "0.3.0",
 )
+
+# And so that zapp can zapp itself...
+# Note that consumers DO NOT get this dependency "for free".
+register_toolchains(
+    "//zapp:python3_toolchain",
+)

example/BUILD

@@ -36,6 +36,12 @@ toolchain(
 
 # Zapp examples & tests
 
+py_test(
+    name = "hello_native",
+    main = "hello.py",
+    srcs = ["hello.py"],
+)
+
 zapp_test(
     name = "hello_script",
     main = "hello.py",

example/WORKSPACE

@@ -29,12 +29,21 @@ git_repository(
     tag = "0.3.0",
 )
 
-register_toolchains("//:python3_toolchain")
+load("@rules_python//python:pip.bzl", "pip_install")
+
+pip_install(
+    name = "my_deps",
+    requirements = "//:requirements.txt",
+)
+
+####################################################################################################
+# rules_zapp
+####################################################################################################
 
 # git_repository(
 #     name = "rules_zapp",
 #     remote = "https://github.com/arrdem/rules_zapp.git",
-#     tag = "0.1.1",
+#     tag = "0.1.3",
 #     # branch = "trunk",
 # )
 
@@ -43,9 +52,7 @@ local_repository(
     path = "../",
 )
 
-load("@rules_python//python:pip.bzl", "pip_install")
+# Use the py3 default toolchain from zapp for a quickstart
-
+register_toolchains(
-pip_install(
+    "@rules_zapp//zapp:python3_toolchain",
-    name = "my_deps",
-    requirements = "//:requirements.txt",
 )

zapp/BUILD

@@ -1,6 +1,36 @@
 package(default_visibility = ["//visibility:public"])
 
-load("zapp.bzl", "zapp_binary")
+load("@rules_python//python:defs.bzl",
+     "py_library",
+     "py_runtime",
+     "py_runtime_pair"
+)
+
+load("zapp.bzl",
+     "zapp_binary"
+)
+
+# The Python runtime we need
+py_runtime(
+    name = "python3_runtime",
+    files = [],
+    interpreter_path = "/usr/bin/python3",
+    python_version = "PY3",
+    visibility = ["//visibility:public"],
+)
+
+py_runtime_pair(
+    name = "python_runtime",
+    py2_runtime = None,
+    py3_runtime = ":python3_runtime",
+)
+
+toolchain(
+    name = "python3_toolchain",
+    toolchain = ":python_runtime",
+    toolchain_type = "@bazel_tools//tools/python:toolchain_type",
+)
+
 
 # Zapp plugins used as a runtime library by rules_zapp
 py_library(
@@ -11,7 +41,7 @@ py_library(
     ]
 )
 
-# Bootstrapping Zapp using py_binary
+
 py_binary(
     name = "zappc",
     main = "compiler/__main__.py",
@@ -23,7 +53,7 @@ py_binary(
     ],
 )
 
-# For testing of zappc
+# Bootstrapping because we can
 zapp_binary(
     name = "zappzappc",
     main = "compiler/__main__.py",

zapp/zapp.bzl

@@ -177,13 +177,14 @@ _zapp_attrs = {
     "wheels": attr.label_list(),
     "entry_point": attr.string(),
     "prelude_points": attr.string_list(),
+    "zip_safe": attr.bool(default = True),
+    # FIXME: These are really toolchain parameters, probably.
     "compiler": attr.label(
         default = Label(DEFAULT_COMPILER),
         executable = True,
         cfg = "host",
     ),
     "shebang": attr.string(default = "/usr/bin/env %py3%"),
-    "zip_safe": attr.bool(default = True),
 }
 
 _zapp = rule(