Add the ability to define template-specific extra variables

The ability to generate dynamic variables is often needed when defining
more complicated templates (for instance, programmatically generate
slurm job headers.) Having this template-specific option to generate
extra rendering vars reduces the need to ingest (more global-scoped)
variables via `define_variables` via phase hooks.

lib/ramble/ramble/application.py

@@ -2270,7 +2270,7 @@ def _get_template_config(
                     break
             if not found:
                 raise ApplicationError(f"Object {obj.name} is missing template file at {src_path}")
-            return {**tpl_config, "src_path": src_path}
+            return (obj, {**tpl_config, "src_path": src_path})
 
         for tpl_config in self.templates.values():
             yield _get_template_config(self, tpl_config)
@@ -2289,10 +2289,14 @@ def _get_template_config(
 
     def _render_object_templates(self, extra_vars):
         run_dir = self.expander.experiment_run_dir
-        for tpl_config in self._object_templates():
+        for obj, tpl_config in self._object_templates():
             src_path = tpl_config["src_path"]
             with open(src_path) as f_in:
                 content = f_in.read()
+            extra_vars_func_name = tpl_config.get("extra_vars_func_name")
+            if extra_vars_func_name is not None:
+                extra_vars_func = getattr(obj, extra_vars_func_name)
+                extra_vars.update(extra_vars_func())
             rendered = self.expander.expand_var(content, extra_vars=extra_vars)
             out_path = os.path.join(run_dir, tpl_config["dest_name"])
             perm = tpl_config.get("content_perm", _DEFAULT_CONTENT_PERM)
@@ -2303,7 +2307,7 @@ def _render_object_templates(self, extra_vars):
 
     def _define_object_template_vars(self):
         run_dir = self.expander.experiment_run_dir
-        for tpl_config in self._object_templates():
+        for _, tpl_config in self._object_templates():
             var_name = tpl_config["var_name"]
             if var_name is not None:
                 path = os.path.join(run_dir, tpl_config["dest_name"])

lib/ramble/ramble/language/shared_language.py

@@ -6,6 +6,8 @@
 # option. This file may not be copied, modified, or distributed
 # except according to those terms.
 
+from typing import Optional
+
 import ramble.language.language_base
 import ramble.language.language_helpers
 import ramble.success_criteria
@@ -480,7 +482,12 @@ def _execute_target_shells(obj):
 
 @shared_directive("templates")
 def register_template(
-    name: str, src_name: str, dest_name: str, define_var: bool = True, output_perm=None
+    name: str,
+    src_name: str,
+    dest_name: str,
+    define_var: bool = True,
+    extra_vars_func: Optional[str] = None,
+    output_perm=None,
 ):
     """Directive to define an object-specific template to be rendered into experiment run_dir.
 
@@ -498,15 +505,19 @@ def register_template(
         dest_name: The leaf name of the rendered output under the experiment
                    run directory.
         define_var: Controls if a variable named `name` should be defined.
+        extra_vars_func: If present, the name of the function to call to return
+                         a dict of extra variables used to render the template.
         output_perm: The chmod mask for the rendered output file.
     """
 
     def _define_template(obj):
         var_name = name if define_var else None
+        extra_vars_func_name = f"_{extra_vars_func}" if extra_vars_func is not None else None
         obj.templates[name] = {
             "src_name": src_name,
             "dest_name": dest_name,
             "var_name": var_name,
+            "extra_vars_func_name": extra_vars_func_name,
             "output_perm": output_perm,
         }
 

var/ramble/repos/builtin.mock/applications/template/application.py

@@ -25,15 +25,14 @@ class Template(ExecutableApplication):
         workload="test_template",
     )
 
-    register_phase(
-        "ingest_dynamic_variables",
-        pipeline="setup",
-        run_before=["make_experiments"],
+    register_template(
+        name="bar",
+        src_name="bar.tpl",
+        dest_name="bar.sh",
+        extra_vars_func="bar_vars",
     )
 
-    def _ingest_dynamic_variables(self, workspace, app_inst):
+    def _bar_vars(self):
         expander = self.expander
         val = expander.expand_var('"hello {hello_name}"')
-        self.define_variable("dynamic_hello_world", val)
-
-    register_template("bar", src_name="bar.tpl", dest_name="bar.sh")
+        return {"dynamic_hello_world": val}