Added Rust SDK version toggler

rust_dev_preview/tools/requirements.txt

@@ -0,0 +1 @@
+tomlkit==0.12.1

rust_dev_preview/tools/toggle_sdk_branch.py

@@ -0,0 +1,87 @@
+#!/usr/bin/env python3
+
+try:
+    from tomlkit import dumps, parse, TOMLDocument
+except:
+    print("Couldn't import tomlkit, either install it directly or instantiate a venv.")
+    exit(1)
+
+from argparse import ArgumentParser
+from glob import glob
+from typing import Union
+import logging
+
+SDK_ORIGIN = "https://github.com/awslabs/aws-sdk-rust"
+
+
+def list_cargos(pathname: str):
+    for file in glob(f"{pathname}/**/Cargo.toml", recursive=True):
+        yield file
+
+
+def read_cargo(pathname: str) -> TOMLDocument:
+    with open(pathname, "+rt") as cargo:
+        return parse(cargo.read())
+
+
+def write_cargo(pathname: str, cargo: TOMLDocument) -> None:
+    with open(pathname, "+wt") as file:
+        file.write(dumps(cargo))
+
+
+def update_sdk_dependencies(cargo: TOMLDocument, branch: Union["main", "next"]) -> None:
+    dependencies = cargo.get("dependencies", [])
+    for name in dependencies:
+        if isinstance(name, str):
+            dependency = dependencies[name]
+            if (
+                not isinstance(dependency, str)
+                and dependency.get("git", None) == SDK_ORIGIN
+                and dependency.get("branch", None) is not None
+            ):
+                logging.debug(
+                    f"Found SDK crate {name} currently on {dependency['branch']}"
+                )
+                dependency["branch"] = branch
+
+
+def update_cargo(pathname: str, branch: Union["main", "next"], dry_run=False):
+    logging.debug(f"Found Cargo.toml at {pathname}")
+    cargo = read_cargo(pathname)
+    update_sdk_dependencies(cargo, branch)
+    if not dry_run:
+        logging.debug(f"Writing new content to {pathname}")
+        write_cargo(pathname, cargo)
+
+
+arg_parser = ArgumentParser()
+arg_parser.add_argument(
+    "--root",
+    default="../",
+    help="Root path for rust_dev_preview cargos. Default ../ assumes running this script from its location in tools. Update single examples by setting root to their folder directly.",
+)
+arg_parser.add_argument(
+    "--branch", default="main", choices=["main", "next"], help="Branch to use"
+)
+arg_parser.add_argument(
+    "--dry-run",
+    dest="dry_run",
+    action="store_true",
+    default=False,
+    help="Don't write updated Cargo files.",
+)
+arg_parser.add_argument(
+    "--verbose", action="store_true", default=False, help="Write verbose logging"
+)
+
+
+def main():
+    args = arg_parser.parse_args()
+    if args.verbose:
+        logging.basicConfig(level=logging.DEBUG)
+    for f in list_cargos(args.root):
+        update_cargo(f, args.branch, dry_run=args.dry_run)
+
+
+if __name__ == "__main__":
+    main()