fix: Support for dirsGlob

Author: Alan Christie

workflow/workflow_engine.py

@@ -101,6 +101,12 @@
 _LOGGER.setLevel(logging.INFO)
 _LOGGER.addHandler(logging.StreamHandler(sys.stdout))
 
+# The variable expected to bu used by "combiner" steps,
+# those that take inputs from multiple prior steps.
+# This variable gets set to the engine's 'instance-link-glob'
+# pre-defined variable
+_INSTANCE_LINK_GLOB_VARIABLE: str = "dirsGlob"
+
 
 @dataclass
 class StepPreparationResponse:
@@ -664,6 +670,14 @@ def _prepare_step(
                     value = f"{p_i_dir}/{value}"
                 prime_variables[connector.out] = value
 
+        # Combiner's automatically get the 'instance-link-glob' pre-defined variable.
+        # It's injected into the step variables as the _INSTANCE_LINK_GLOB_VARIABLE,
+        # which the combiner is expected to handle.
+        if we_are_a_combiner:
+            prime_variables[_INSTANCE_LINK_GLOB_VARIABLE] = self._predefined_variables[
+                "instance-link-glob"
+            ]
+
         # Our step's prime variables are now set.
 
         # Before we return these to the caller do we have enough