[CLI] Validate node version (#2489)

libs/cli/langgraph_cli/cli.py

@@ -1,4 +1,3 @@
-import json
 import pathlib
 import shutil
 import sys
@@ -354,8 +353,7 @@ def build(
     with Runner() as runner, Progress(message="Pulling...") as set:
         if shutil.which("docker") is None:
             raise click.UsageError("Docker not installed") from None
-        with open(config) as f:
-            config_json = langgraph_cli.config.validate_config(json.load(f))
+        config_json = langgraph_cli.config.validate_config_file(config)
         _build(
             runner, set, config, config_json, base_image, pull, tag, docker_build_args
         )
@@ -435,8 +433,7 @@ tests
 def dockerfile(save_path: str, config: pathlib.Path, add_docker_compose: bool) -> None:
     save_path = pathlib.Path(save_path).absolute()
     secho(f"🔍 Validating configuration at path: {config}", fg="yellow")
-    with open(config, encoding="utf-8") as f:
-        config_json = langgraph_cli.config.validate_config(json.load(f))
+    config_json = langgraph_cli.config.validate_config_file(config)
     secho("✅ Configuration validated!", fg="green")
 
     secho(f"📝 Generating Dockerfile at {save_path}", fg="yellow")
@@ -575,7 +572,7 @@ def dev(
     host: str,
     port: int,
     no_reload: bool,
-    config: str,
+    config: pathlib.Path,
     n_jobs_per_worker: Optional[int],
     no_browser: bool,
     debug_port: Optional[int],
@@ -601,12 +598,9 @@ def dev(
             "Please ensure langgraph-cli is installed with the 'inmem' extra: pip install -U \"langgraph-cli[inmem]\""
         ) from None
 
-    import json
+    config_json = langgraph_cli.config.validate_config_file(config)
 
-    with open(config, encoding="utf-8") as f:
-        config_data = json.load(f)
-
-    graphs = config_data.get("graphs", {})
+    graphs = config_json.get("graphs", {})
     run_server(
         host,
         port,
@@ -674,8 +668,7 @@ def prepare(
     debugger_base_url: Optional[str] = None,
     postgres_uri: Optional[str] = None,
 ):
-    with open(config_path) as f:
-        config = langgraph_cli.config.validate_config(json.load(f))
+    config_json = langgraph_cli.config.validate_config_file(config_path)
     # pull latest images
     if pull:
         runner.run(
@@ -683,9 +676,9 @@ def prepare(
                 "docker",
                 "pull",
                 (
-                    f"langchain/langgraphjs-api:{config['node_version']}"
-                    if config.get("node_version")
-                    else f"langchain/langgraph-api:{config['python_version']}"
+                    f"langchain/langgraphjs-api:{config_json['node_version']}"
+                    if config_json.get("node_version")
+                    else f"langchain/langgraph-api:{config_json['python_version']}"
                 ),
                 verbose=verbose,
             )
@@ -694,7 +687,7 @@ def prepare(
     args, stdin = prepare_args_and_stdin(
         capabilities=capabilities,
         config_path=config_path,
-        config=config,
+        config=config_json,
         docker_compose=docker_compose,
         port=port,
         watch=watch,

libs/cli/langgraph_cli/config.py

@@ -6,6 +6,9 @@ from typing import NamedTuple, Optional, TypedDict, Union
 
 import click
 
+MIN_NODE_VERSION = "20"
+MIN_PYTHON_VERSION = "3.11"
+
 
 class Config(TypedDict):
     python_version: str
@@ -17,9 +20,6 @@ class Config(TypedDict):
     env: Union[dict[str, str], str]
 
 
-MIN_PYTHON_VERSION = "3.11"
-
-
 def _parse_version(version_str: str) -> tuple[int, int]:
     """Parse a version string into a tuple of (major, minor)."""
     try:
@@ -29,6 +29,19 @@ def _parse_version(version_str: str) -> tuple[int, int]:
         raise click.UsageError(f"Invalid version format: {version_str}") from None
 
 
+def _parse_node_version(version_str: str) -> int:
+    """Parse a Node.js version string into a major version number."""
+    try:
+        if "." in version_str:
+            raise ValueError("Node.js version must be major version only")
+        return int(version_str)
+    except ValueError:
+        raise click.UsageError(
+            f"Invalid Node.js version format: {version_str}. "
+            "Use major version only (e.g., '20')."
+        ) from None
+
+
 def validate_config(config: Config) -> Config:
     config = (
         {
@@ -49,11 +62,17 @@ def validate_config(config: Config) -> Config:
     )
 
     if config.get("node_version"):
-        if config["node_version"] not in ("20",):
-            raise click.UsageError(
-                f"Unsupported Node.js version: {config['node_version']}. "
-                "Currently only `node_version: \"20\"` is supported."
-            )
+        node_version = config["node_version"]
+        try:
+            major = _parse_node_version(node_version)
+            min_major = _parse_node_version(MIN_NODE_VERSION)
+            if major < min_major:
+                raise click.UsageError(
+                    f"Node.js version {node_version} is not supported. "
+                    f"Minimum required version is {MIN_NODE_VERSION}."
+                )
+        except ValueError as e:
+            raise click.UsageError(str(e)) from None
 
     if config.get("python_version"):
         pyversion = config["python_version"]
@@ -85,6 +104,48 @@ def validate_config(config: Config) -> Config:
     return config
 
 
+def validate_config_file(config_path: pathlib.Path) -> Config:
+    with open(config_path) as f:
+        config = json.load(f)
+    validated = validate_config(config)
+    # Enforce the package.json doesn't enforce an
+    # incompatible Node.js version
+    if validated.get("node_version"):
+        package_json_path = config_path.parent / "package.json"
+        if package_json_path.is_file():
+            try:
+                with open(package_json_path) as f:
+                    package_json = json.load(f)
+                    if "engines" in package_json:
+                        engines = package_json["engines"]
+                        if any(engine != "node" for engine in engines.keys()):
+                            raise click.UsageError(
+                                "Only 'node' engine is supported in package.json engines."
+                                f" Got engines: {list(engines.keys())}"
+                            )
+                        if engines:
+                            node_version = engines["node"]
+                            try:
+                                major = _parse_node_version(node_version)
+                                min_major = _parse_node_version(MIN_NODE_VERSION)
+                                if major < min_major:
+                                    raise click.UsageError(
+                                        f"Node.js version in package.json engines must be >= {MIN_NODE_VERSION} "
+                                        f"(major version only), got '{node_version}'. Minor/patch versions "
+                                        "(like '20.x.y') are not supported to prevent deployment issues "
+                                        "when new Node.js versions are released."
+                                    )
+                            except ValueError as e:
+                                raise click.UsageError(str(e)) from None
+
+            except json.JSONDecodeError:
+                raise click.UsageError(
+                    "Invalid package.json found in langgraph "
+                    f"config directory {package_json_path}: file is not valid JSON"
+                ) from None
+    return validated
+
+
 class LocalDeps(NamedTuple):
     pip_reqs: list[tuple[pathlib.Path, str]]
     real_pkgs: dict[pathlib.Path, str]