From e602aed0193ebbd936d441523d49974e2ac63223 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kristian=20H=2E=20M=C3=B8ller?= <khm@dmi.dk>
Date: Thu, 7 May 2026 09:59:16 +0200
Subject: [PATCH] Added temporary verification for the number of ensemble
 members being one

---
 CHANGELOG.md          |  4 ++++
 sunflow/main.py       |  2 ++
 sunflow/validation.py | 23 +++++++++++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1174b3f..29b9fcc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Added a check for the number of ensemble members, as the code currently supports only one [!13](https://github.com/dmidk/sunflow/pull/13), @KristianHMoller
+
 ## [v1.1.0]
 
 ### Added
diff --git a/sunflow/main.py b/sunflow/main.py
index e7402b2..13a765b 100644
--- a/sunflow/main.py
+++ b/sunflow/main.py
@@ -31,6 +31,7 @@
     validate_clearsky_shapes,
     validate_config,
     validate_data_shape,
+    validate_nowcast_config,
     validate_run_mode,
     verify_environment_variables,
 )
@@ -407,6 +408,7 @@ def cli() -> None:
 
     validate_run_mode(run_mode, dataset_name)
     validate_config(config, dataset_name)
+    validate_nowcast_config(nowcast_config)
     verify_environment_variables(run_mode, dataset_name)
 
     # Determine the time steps to run
diff --git a/sunflow/validation.py b/sunflow/validation.py
index 09c9e2c..21a1cae 100644
--- a/sunflow/validation.py
+++ b/sunflow/validation.py
@@ -9,6 +9,8 @@
 import xarray as xr
 from loguru import logger
 
+from .config import NowcastConfig
+
 
 class MissingClearskyDataError(RuntimeError):
     pass
@@ -44,6 +46,27 @@ def validate_config(config: dict[str, Any], dataset_name: str) -> None:
         sys.exit(1)
 
 
+def validate_nowcast_config(nowcast_config: NowcastConfig) -> None:
+    """Validate that the options selected for the nowcast config are valid.
+
+    Checks the nowcast config created from imported environment variables.
+    Exits immediately for invalid choices.
+
+    Args:
+        nowcast_config: Instance of the NowcastConfig class
+        loaded from environment variables in config.py.
+
+    Raises:
+        SystemExit: If any invalid choice is detected.
+    """
+    if nowcast_config.ens_members != 1:
+        logger.error(
+            f"Invalid nowcast configuration: Currently, only ens_members=1 is supported. "
+            f"Current value: {nowcast_config.ens_members}. Exiting.\n"
+        )
+        sys.exit(1)
+
+
 def validate_run_mode(run_mode: str, dataset_name: str) -> None:
     """Validate that the run mode is compatible with the dataset.