substitute mount and view variables at configuration time

Author: bcumming

stackinator/recipe.py

@@ -292,6 +292,16 @@ def environment_view_meta(self):
         view_meta = {}
         for _, env in self.environments.items():
             for view in env["views"]:
+                # recipe authors can substitute the name of the view, the mount
+                # and view path into environment variables using '$@key@' where
+                # key is one of view_name, mount and view_path.
+                substitutions = {
+                        "view_name": view["name"],
+                        "mount": self.mount,
+                        "view_path": view["config"]["root"]
+                }
+                fill = lambda s: re.sub(r"\$@(\w+)@", lambda m: substitutions.get(m.group(1), m.group(0)), s,)
+
                 ev_inputs = view["extra"]["env_vars"]
                 env = envvars.EnvVarSet()
 
@@ -302,6 +312,9 @@ def environment_view_meta(self):
 
                 for v in ev_inputs["set"]:
                     ((name, value),) = v.items()
+                    if value is not None:
+                        value = fill(value)
+
                     # insist that the only 'set' operation on prefix variables is to unset/reset them
                     # this requires that users use append and prepend to build up the variables
                     if envvars.is_list_var(name) and value is not None:
@@ -313,12 +326,16 @@ def environment_view_meta(self):
                             env.set_scalar(name, value)
                 for v in ev_inputs["prepend_path"]:
                     ((name, value),) = v.items()
+                    if value is not None:
+                        value = fill(value)
                     if not envvars.is_list_var(name):
                         raise RuntimeError(f"{name} in the {view['name']} view is not a known prefix path variable")
 
                     env.set_list(name, [value], envvars.EnvVarOp.APPEND)
                 for v in ev_inputs["append_path"]:
                     ((name, value),) = v.items()
+                    if value is not None:
+                        value = fill(value)
                     if not envvars.is_list_var(name):
                         raise RuntimeError(f"{name} in the {view['name']} view is not a known prefix path variable")