Make node actions args limit user error (#38319)

AWS Lambda has a 6MiB limit on request size. This PR adds a check that arguments don't exceed 5MiB and makes it a user error instead of an internal server error.

GitOrigin-RevId: b7f14275a160e04c7b391bb64c582846157db4c5

Author: emmaling27

crates/node_executor/src/executor.rs

@@ -120,6 +120,11 @@ pub fn error_response_json(message: &str) -> JsonValue {
     })
 }
 
+// AWS Lambda has a 6MiB limit on invoke request size,
+// and we leave some headroom for other data in `ExecuteRequest` like
+// environment variables which could take up to 100 * 8KiB = 800 KiB
+const NODE_ACTIONS_ARGS_SIZE_LIMIT: usize = 5 * 1024 * 1024; // 5MiB
+
 pub static EXECUTE_TIMEOUT_RESPONSE_JSON: LazyLock<JsonValue> = LazyLock::new(|| {
     error_response_json(
         "Function execution unexpectedly timed out. Check your function for infinite loops or \
@@ -230,6 +235,7 @@ impl<RT: Runtime> Actions<RT> {
             + Send,
     ) -> anyhow::Result<NodeActionOutcome> {
         let path = request.path_and_args.path().clone();
+        anyhow::ensure!(request.path_and_args.args_size() < NODE_ACTIONS_ARGS_SIZE_LIMIT, ErrorMetadata::bad_request("ArgsTooLarge", format!("Node actions arguments size is too large: {} bytes. The maximum size is {} bytes.", request.path_and_args.args_size(), NODE_ACTIONS_ARGS_SIZE_LIMIT)));
         let timer = node_executor("execute");
         let request = ExecutorRequest::Execute {
             request,

crates/udf/src/validation.rs

@@ -505,6 +505,10 @@ impl ValidatedPathAndArgs {
         }))
     }
 
+    pub fn args_size(&self) -> usize {
+        self.args.heap_size()
+    }
+
     #[cfg(any(test, feature = "testing"))]
     pub fn new_for_tests(
         udf_path: CanonicalizedUdfPath,

npm-packages/docs/docs/functions/runtimes.mdx

@@ -156,3 +156,5 @@ without the `"use node"` directive should not import any files with the
 `"use node"` directive. Files that contain no Convex functions, like a
 `convex/utils.ts` file, also need the "use node" directive if they use
 Node.js-specific libraries.
+
+Note that argument size limits are lower (5MiB instead of 16MiB).

npm-packages/docs/docs/production/state/limits.mdx

@@ -62,7 +62,7 @@ Applied per document and to any nested `Object` unless stated otherwise.
 | Function calls                                                               | 1,000,000/month included<br/>(on Starter: $2.20 per additional 1,000,000) | 25,000,000/month included<br/>$2 per additional 1,000,000 | Explicit client calls, scheduled executions, subscription updates, and file accesses count as function calls. |
 | Action execution                                                             | 20 GiB-hours included<br/>(on Starter: $0.33/GiB-hour additional)         | 250 GiB-hours included<br/>$0.30/GiB-hour additional      | Convex runtime: 64 MiB RAM.<br/>Node.js runtime: 512 MiB RAM.                                                 |
 | Code size                                                                    | 32 MiB                                                                    | 32 MiB                                                    | Per deployment.                                                                                               |
-| Function argument size                                                       | 16 MiB                                                                    | 16 MiB                                                    |                                                                                                               |
+| Function argument size                                                       | 16 MiB                                                                    | 16 MiB                                                    | Node actions only support arguments up to 5MiB.                                                               |
 | Function return value size                                                   | 16 MiB                                                                    | 16 MiB                                                    |                                                                                                               |
 | HTTP action response size                                                    | 20 MiB                                                                    | 20 MiB                                                    | There is no specific limit on request size                                                                    |
 | Length of a console.log line                                                 | 4 KiB                                                                     | 4 KiB                                                     |                                                                                                               |