Allow users without equilibrium to run ert with FLOW simulator.

Create flow_config.yml config file if it is not found in the env variables.

src/ert/shared/share/ert/forward-models/res/script/ecl_config.py

@@ -3,7 +3,9 @@
 import subprocess
 import sys
 from typing import Any, Dict, List, Optional
-
+from pathlib import Path
+import platform
+import shutil
 import yaml
 
 
@@ -203,8 +205,39 @@ class FlowConfig(EclConfig):
 
     def __init__(self):
         config_file = os.getenv("FLOW_SITE_CONFIG", default=self.DEFAULT_CONFIG_FILE)
+        if not Path(config_file).exists():
+            config_file = self.init_flow_config()
         super().__init__(config_file, simulator_name="flow")
 
+    @staticmethod
+    def locate_flow_binary() -> str:
+        """Locate the path for a flow executable.
+
+        Returns the empty string if there is nothing to be found in $PATH."""
+        rhel_version = "7"
+        if "el8" in platform.release():
+            rhel_version = "8"
+        candidates = ["flow",
+                      f"/project/res/x86_64_RH_{rhel_version}/bin/flowdaily"]
+        for candidate in candidates:
+            foundpath = shutil.which(candidate)
+            if foundpath is not None:
+                return foundpath
+        return ""
+
+    @staticmethod
+    def init_flow_config() -> str:
+        binary_path = FlowConfig.locate_flow_binary()
+        conf = {
+            "default_version": "default",
+            "versions": {"default": {"scalar": {"executable": binary_path}}},
+        }
+        flow_config_yml = Path("flow_config.yml")
+        flow_config_yml.write_text(yaml.dump(conf), encoding="utf-8")
+        flow_config_path = str(flow_config_yml.absolute())
+        os.environ["FLOW_SITE_CONFIG"] = flow_config_path
+        return flow_config_path
+
 
 class EclrunConfig:
     """This class contains configurations for using the new eclrun binary