Render sql_header for dbt show

core/dbt/task/show.py

@@ -11,6 +11,9 @@
 from dbt.task.compile import CompileTask, CompileRunner
 from dbt.task.seed import SeedRunner
 
+from dbt.context.providers import generate_runtime_model_context
+from dbt.clients.jinja import get_rendered
+
 
 class ShowRunner(CompileRunner):
     def __init__(self, config, adapter, node, node_index, num_nodes):
@@ -23,13 +26,19 @@ def execute(self, compiled_node, manifest):
         # Allow passing in -1 (or any negative number) to get all rows
         limit = None if self.config.args.limit < 0 else self.config.args.limit
 
+        compiled_code = compiled_node.compiled_code
+
         if "sql_header" in compiled_node.unrendered_config:
-            compiled_node.compiled_code = (
-                compiled_node.unrendered_config["sql_header"] + compiled_node.compiled_code
-            )
+            # Currently, we only render sql_header at *parse* time for *running* models:
+            # See dbt-core issues #2793, #3264, #7151
+            # So technically this should be "generate_parser_model_context" (I think) instead of "generate_runtime_model_context"
+            # Generating the context will be slower if we don't actually need to render the sql_header (if it contains no Jinja)
+            context = generate_runtime_model_context(compiled_node, self.config, manifest)
+            sql_header = get_rendered(compiled_node.unrendered_config["sql_header"], context)
+            compiled_code = sql_header + compiled_code
 
         adapter_response, execute_result = self.adapter.execute(
-            compiled_node.compiled_code, fetch=True, limit=limit
+            compiled_code, fetch=True, limit=limit
         )
         end_time = time.time()
 

tests/functional/show/fixtures.py

@@ -12,7 +12,7 @@
 
 models__sql_header = """
 {% call set_sql_header(config) %}
-set session time zone 'Asia/Kolkata';
+set session time zone '{{ var("timezone") }}';
 {%- endcall %}
 select current_setting('timezone') as timezone
 """

tests/functional/show/test_show.py

@@ -110,8 +110,10 @@ def test_seed(self, project):
         assert "Previewing node 'sample_seed'" in log_output
 
     def test_sql_header(self, project):
-        run_dbt(["build"])
-        (results, log_output) = run_dbt_and_capture(["show", "--select", "sql_header"])
+        run_dbt(["build", "--vars", "timezone: Asia/Kolkata"])
+        (results, log_output) = run_dbt_and_capture(
+            ["show", "--select", "sql_header", "--vars", "timezone: Asia/Kolkata"]
+        )
         assert "Asia/Kolkata" in log_output