[Resolve Sceptre#1334] Add a dump vars command

The dump vars command dumps the compiled templating_vars for the purpose
of additional debugging information.

sceptre/cli/dump.py

@@ -53,3 +53,36 @@ def dump_config(ctx, path):
     else:
         for config in output:
             write(config, output_format)
+
+
+@dump_group.command(name="vars")
+@click.argument("path")
+@click.pass_context
+@catch_exceptions
+def dump_config(ctx, path):
+    """
+    Dump the template vars.
+    \f
+
+    :param path: Path to execute the command on or path to stack group
+    """
+    context = SceptreContext(
+        command_path=path,
+        command_params=ctx.params,
+        project_path=ctx.obj.get("project_path"),
+        user_variables=ctx.obj.get("user_variables"),
+        output_format=ctx.obj.get("output_format"),
+        options=ctx.obj.get("options"),
+        ignore_dependencies=ctx.obj.get("ignore_dependencies"),
+    )
+    plan = SceptrePlan(context)
+    responses = plan.dump_vars()
+
+    output = []
+    for stack, vars in responses.items():
+        output.append({stack.external_name: vars})
+
+    output_format = "json" if context.output_format == "json" else "yaml"
+
+    for vars in output:
+        write(vars, output_format)

sceptre/config/reader.py

@@ -602,6 +602,7 @@ def _construct_stack(self, rel_path, stack_group_config=None):
             obsolete=config.get("obsolete", False),
             stack_group_config=parsed_stack_group_config,
             config=config,
+            vars=self.templating_vars,
         )
 
         del self.templating_vars["stack_group_config"]

sceptre/plan/actions.py

@@ -1150,3 +1150,10 @@ def dump_config(self):
         Dump the config for a stack.
         """
         return self.stack.config
+
+    @add_stack_hooks
+    def dump_vars(self):
+        """
+        Dump the vars for a stack.
+        """
+        return self.stack.vars

sceptre/plan/plan.py

@@ -440,3 +440,10 @@ def dump_config(self, *args):
         """
         self.resolve(command=self.dump_config.__name__)
         return self._execute(*args)
+
+    def dump_vars(self, *args):
+        """
+        Dump the vars for a stack.
+        """
+        self.resolve(command=self.dump_vars.__name__)
+        return self._execute(*args)

sceptre/stack.py

@@ -123,6 +123,10 @@ class Stack:
            If not supplied, Sceptre uses default value (3600 seconds)
 
     :param stack_group_config: The StackGroup config for the Stack
+
+    :param config: The complete config for the stack. Used by dump config.
+
+    :param vars: The complete templating vars for the Stack. Used by dump vars.
     """
 
     parameters = ResolvableContainerProperty("parameters")
@@ -195,6 +199,7 @@ def __init__(
         obsolete=False,
         stack_group_config: dict = {},
         config: dict = {},
+        vars: dict = {},
     ):
         self.logger = logging.getLogger(__name__)
 
@@ -213,6 +218,7 @@ def __init__(
         )
         self.stack_group_config = stack_group_config or {}
         self.config = config or {}
+        self.vars = vars or {}
         self.stack_timeout = stack_timeout
         self.profile = profile
         self.template_key_prefix = template_key_prefix