feat: demonstrate python run_binary/macro

cli/BUILD.bazel

@@ -1,9 +1,20 @@
 load("@rules_python//python:defs.bzl", "py_binary")
 load("@pip//:requirements.bzl", "requirement")
+load("//tools:py_header.bzl", "myorg_py_header")
+
+myorg_py_header(
+    name = "fill_template",
+    out = "header.txt",
+    tmpl = "header.txt.tmpl",
+)
 
 py_binary(
     name = "cli",
     srcs = ["__main__.py"],
     main = "__main__.py",
-    deps = [requirement("requests")],
+    deps = [
+        requirement("requests"),
+        requirement("bazel-runfiles"),
+    ],
+    data = ["header.txt"],
 )

cli/__main__.py

@@ -1,4 +1,7 @@
 import requests
+import runfiles
 
+with open(runfiles.Create().Rlocation("_main/cli/header.txt"), "r") as f:
+  print(f.read())
 r = requests.get('http://localhost:8081')
 print(r.json())

cli/header.txt.tmpl

@@ -0,0 +1,4 @@
+Thanks for running our <codename> CLI.
+
+Note, you will need to start the server first.
+Built at {{timestamp}}!

requirements.txt

@@ -1 +1,4 @@
 requests
+Jinja2
+jinja2-cli
+bazel-runfiles

tools/BUILD.bazel

@@ -0,0 +1,21 @@
+load("@rules_python//python/entry_points:py_console_script_binary.bzl", "py_console_script_binary")
+
+package(default_visibility = ["//visibility:public"])
+py_console_script_binary(
+    name = "jinja2",
+    pkg = "@pip//jinja2_cli:pkg",
+)
+
+load("@aspect_bazel_lib//lib:jq.bzl", "jq")
+
+jq(
+    name = "data",
+    srcs = [],
+    filter = "|".join([
+        # Don't directly reference $STAMP as it's only set when stamping
+        # This 'as' syntax results in $stamp being null in unstamped builds.
+        "$ARGS.named.STAMP as $stamp",
+        # Provide a default using the "alternative operator" in case $stamp is null.
+        """.timestamp = ($stamp.BUILD_TIMESTAMP // "<unstamped>")""",
+    ]),
+)

tools/py_header.bzl

@@ -0,0 +1,16 @@
+"TODO"
+load("@aspect_bazel_lib//lib:run_binary.bzl", "run_binary")
+
+def myorg_py_header(name, tmpl, out, **kwargs):
+    run_binary(
+        name = name,
+        outs = [out],
+        srcs = [
+            tmpl,
+            "//tools:data.json",
+        ],
+        # The tool to run in the action
+        tool = "//tools:jinja2",
+        args = ["--format=json", "-o", "$(execpath %s)" % out, "$(execpath %s)" % tmpl, "$(execpath //tools:data.json)"],
+        **kwargs,
+    )