feat: Dynamically determine latest init runtime

samcli/commands/exceptions.py

@@ -152,3 +152,10 @@ class LinterRuleMatchedException(UserException):
     """
     The linter matched a rule meaning that the template linting failed
     """
+
+
+class PopularRuntimeNotFoundException(Exception):
+    """
+    Exception thrown when we were not able to parse the SUPPORTED_RUNTIMES
+    constant correctly for the latest runtime
+    """

samcli/commands/init/interactive_init_flow.py

@@ -4,14 +4,15 @@
 
 import logging
 import pathlib
+import re
 import tempfile
 from typing import Optional, Tuple
 
 import click
 from botocore.exceptions import ClientError, WaiterError
 
 from samcli.commands._utils.options import generate_next_command_recommendation
-from samcli.commands.exceptions import InvalidInitOptionException, SchemasApiException
+from samcli.commands.exceptions import InvalidInitOptionException, PopularRuntimeNotFoundException, SchemasApiException
 from samcli.commands.init.init_flow_helpers import (
     _get_image_from_runtime,
     _get_runtime_from_image,
@@ -28,6 +29,7 @@
 )
 from samcli.lib.config.samconfig import DEFAULT_CONFIG_FILE_NAME
 from samcli.lib.schemas.schemas_code_manager import do_download_source_code_binding, do_extract_and_merge_schemas_code
+from samcli.lib.utils.architecture import SUPPORTED_RUNTIMES
 from samcli.lib.utils.osutils import remove
 from samcli.lib.utils.packagetype import IMAGE, ZIP
 from samcli.local.common.runtime_template import (
@@ -323,6 +325,60 @@ def _generate_from_use_case(
         )
 
 
+def _get_latest_python_runtime() -> str:
+    """
+    Returns the latest support version of Python
+    SAM CLI supports
+
+    Returns
+    -------
+    str:
+        The name of the latest Python runtime (ex. "python3.12")
+    """
+    latest_major = 0
+    latest_minor = 0
+
+    compiled_regex = re.compile(r"python(.*?)\.(.*)")
+
+    for runtime in SUPPORTED_RUNTIMES:
+        if not runtime.startswith("python"):
+            continue
+
+        # python3.12 => 3.12 => (3, 12)
+        version_match = re.match(compiled_regex, runtime)
+
+        if not version_match:
+            LOG.debug(f"Failed to match version while checking {runtime}")
+            continue
+
+        matched_groups = version_match.groups()
+
+        try:
+            version_major = int(matched_groups[0])
+            version_minor = int(matched_groups[1])
+        except (ValueError, IndexError):
+            LOG.debug(f"Failed to parse version while checking {runtime}")
+            continue
+
+        if version_major > latest_major:
+            latest_major = version_major
+            latest_minor = version_minor
+        elif version_major == latest_major:
+            latest_minor = version_minor if version_minor > latest_minor else latest_minor
+
+    if not latest_major:
+        # major version is still 0, assume that something went wrong
+        # this in theory should not happen as long as Python is
+        # listed in the SUPPORTED_RUNTIMES constant
+        raise PopularRuntimeNotFoundException("Was unable to search for the latest supported runtime")
+
+    selected_version = f"python{latest_major}.{latest_minor}"
+
+    LOG.debug(f"Using {selected_version} as the latest runtime version")
+
+    return selected_version
+
+
 def _generate_default_hello_world_application(
     use_case: str,
     package_type: Optional[str],
@@ -356,8 +412,10 @@ def _generate_default_hello_world_application(
     """
     is_package_type_image = bool(package_type == IMAGE)
     if use_case == "Hello World Example" and not (runtime or base_image or is_package_type_image or dependency_manager):
-        if click.confirm("\nUse the most popular runtime and package type? (Python and zip)"):
-            runtime, package_type, dependency_manager, pt_explicit = "python3.9", ZIP, "pip", True
+        latest_python = _get_latest_python_runtime()
+
+        if click.confirm(f"\nUse the most popular runtime and package type? ({latest_python} and zip)"):
+            runtime, package_type, dependency_manager, pt_explicit = _get_latest_python_runtime(), ZIP, "pip", True
     return (runtime, package_type, dependency_manager, pt_explicit)
 
 

tests/unit/commands/init/test_cli.py

@@ -3,6 +3,8 @@
 import shutil
 import subprocess
 import tempfile
+from unittest import mock
+from parameterized import parameterized
 import requests
 from pathlib import Path
 from typing import Dict, Any
@@ -13,7 +15,7 @@
 import click
 from click.testing import CliRunner
 
-from samcli.commands.exceptions import UserException
+from samcli.commands.exceptions import PopularRuntimeNotFoundException, UserException
 from samcli.commands.init import cli as init_cmd
 from samcli.commands.init.command import do_cli as init_cli
 from samcli.commands.init.command import PackageType
@@ -25,7 +27,7 @@
     get_template_value,
     template_does_not_meet_filter_criteria,
 )
-from samcli.commands.init.interactive_init_flow import get_sorted_runtimes
+from samcli.commands.init.interactive_init_flow import _get_latest_python_runtime, get_sorted_runtimes
 from samcli.lib.init import GenerateProjectFailedError
 from samcli.lib.utils import osutils
 from samcli.lib.utils.git_repo import GitRepo
@@ -2006,9 +2008,9 @@ def test_init_cli_generate_default_hello_world_app(
         request_mock.side_effect = requests.Timeout()
         init_options_from_manifest_mock.return_value = [
             {
-                "directory": "python3.9/cookiecutter-aws-sam-hello-python",
+                "directory": "python3.12/cookiecutter-aws-sam-hello-python",
                 "displayName": "Hello World Example",
-                "dependencyManager": "npm",
+                "dependencyManager": "pip",
                 "appTemplate": "hello-world",
                 "packageType": "Zip",
                 "useCaseName": "Hello World Example",
@@ -2026,10 +2028,10 @@ def test_init_cli_generate_default_hello_world_app(
 
         get_preprocessed_manifest_mock.return_value = {
             "Hello World Example": {
-                "python3.9": {
+                "python3.12": {
                     "Zip": [
                         {
-                            "directory": "python3.9/cookiecutter-aws-sam-hello-python3.9",
+                            "directory": "python3.12/cookiecutter-aws-sam-hello-python3.12",
                             "displayName": "Hello World Example",
                             "dependencyManager": "pip",
                             "appTemplate": "hello-world",
@@ -2070,16 +2072,17 @@ def test_init_cli_generate_default_hello_world_app(
 
         runner = CliRunner()
         result = runner.invoke(init_cmd, input=user_input)
+        print(result.stdout)
         self.assertFalse(result.exception)
         generate_project_patch.assert_called_once_with(
             ANY,
             ZIP,
-            "python3.9",
+            "python3.12",
             "pip",
             ".",
             "test-project",
             True,
-            {"project_name": "test-project", "runtime": "python3.9", "architectures": {"value": ["x86_64"]}},
+            {"project_name": "test-project", "runtime": "python3.12", "architectures": {"value": ["x86_64"]}},
             False,
             False,
             False,
@@ -3193,3 +3196,35 @@ def test_init_cli_generate_app_template_provide_via_application_insights_options
             True,
             False,
         )
+
+    @parameterized.expand(
+        [
+            ({"python3.2": Any, "python3.100000": Any, "python3.14": Any}, "python3.100000"),
+            ({"python7.8": Any, "python9.1": Any}, "python9.1"),
+            ({"python6.1": Any, "python4.7": Any}, "python6.1"),
+        ]
+    )
+    def test_latest_python_fetcher_correct_latest(self, versions, expected):
+        with mock.patch(
+            "samcli.commands.init.interactive_init_flow.SUPPORTED_RUNTIMES",
+            versions,
+        ):
+            result = _get_latest_python_runtime()
+
+        self.assertEqual(result, expected)
+
+    def test_latest_python_fetcher_has_valid_supported_runtimes(self):
+        """
+        Mainly checks if the SUPPORTED_RUNTIMES constant actually has
+        Python runtime inside of it
+        """
+        result = _get_latest_python_runtime()
+        self.assertTrue(result, "Python was not found in the SUPPORTED_RUNTIMES const")
+
+    def test_latest_python_fetchers_raises_not_found(self):
+        with mock.patch(
+            "samcli.commands.init.interactive_init_flow.SUPPORTED_RUNTIMES",
+            {"invalid": Any},
+        ):
+            with self.assertRaises(PopularRuntimeNotFoundException):
+                _get_latest_python_runtime()