[KED-2419] Make pipeline and Pipeline consistent, take 2

RELEASE.md

@@ -1,3 +1,14 @@
+# Release 0.17.7
+
+## Major features and improvements
+* `pipeline` now accepts `tags` and a collection of `Node`s and/or `Pipeline`s rather than just a single `Pipeline` object. `pipeline` should be used in preference to `Pipeline` when creating a Kedro pipeline.
+
+## Bug fixes and other changes
+
+## Minor breaking changes to the API
+
+## Upcoming deprecations for Kedro 0.18.0
+
 # Release 0.17.6
 
 ## Major features and improvements

features/steps/cli_steps.py

@@ -496,7 +496,7 @@ def check_empty_pipeline_exists(context):
         / context.project_name.replace("-", "_")
         / "pipeline_registry.py"
     )
-    assert '"__default__": Pipeline([])' in pipeline_file.read_text("utf-8")
+    assert '"__default__": pipeline([])' in pipeline_file.read_text("utf-8")
 
 
 @then("the pipeline should contain nodes")
@@ -510,7 +510,7 @@ def check_pipeline_not_empty(context):
         / context.project_name.replace("-", "_")
         / "pipeline_registry.py"
     )
-    assert "pipeline = Pipeline([])" not in pipeline_file.read_text("utf-8")
+    assert "pipeline = pipeline([])" not in pipeline_file.read_text("utf-8")
 
 
 @then("the console log should show that {number} nodes were run")

features/steps/test_plugin/plugin.py

@@ -2,7 +2,7 @@
 import logging
 
 from kedro.framework.hooks import hook_impl
-from kedro.pipeline import Pipeline, node
+from kedro.pipeline import node, pipeline
 
 
 class MyPluginHook:
@@ -15,7 +15,7 @@ def after_catalog_created(
     @hook_impl
     def register_pipelines(self):  # pylint: disable=no-self-use
         return {
-            "from_plugin": Pipeline([node(lambda: "sth", inputs=None, outputs="x")])
+            "from_plugin": pipeline([node(lambda: "sth", inputs=None, outputs="x")])
         }
 
 

features/steps/test_starter/{{ cookiecutter.repo_name }}/src/{{ cookiecutter.python_package }}/pipelines/data_engineering/pipeline.py

@@ -4,13 +4,13 @@
 Delete this when you start working on your own Kedro project.
 """
 
-from kedro.pipeline import Pipeline, node
+from kedro.pipeline import node, pipeline
 
 from .nodes import split_data
 
 
 def create_pipeline(**kwargs):
-    return Pipeline(
+    return pipeline(
         [
             node(
                 split_data,

features/steps/test_starter/{{ cookiecutter.repo_name }}/src/{{ cookiecutter.python_package }}/pipelines/data_science/pipeline.py

@@ -4,13 +4,13 @@
 Delete this when you start working on your own Kedro project.
 """
 
-from kedro.pipeline import Pipeline, node
+from kedro.pipeline import node, pipeline
 
 from .nodes import predict, report_accuracy, train_model
 
 
 def create_pipeline(**kwargs):
-    return Pipeline(
+    return pipeline(
         [
             node(
                 train_model,

kedro/pipeline/modular_pipeline.py

@@ -1,6 +1,6 @@
 """Helper to integrate modular pipelines into a master pipeline."""
 import copy
-from typing import AbstractSet, Dict, List, Set, Union
+from typing import AbstractSet, Dict, Iterable, List, Set, Union
 
 from kedro.pipeline.node import Node
 from kedro.pipeline.pipeline import (
@@ -69,34 +69,40 @@ def _validate_datasets_exist(
 
 
 def pipeline(
-    pipe: Pipeline,
+    pipe: Union[Iterable[Union[Node, Pipeline]], Pipeline],
     *,
     inputs: Union[str, Set[str], Dict[str, str]] = None,
     outputs: Union[str, Set[str], Dict[str, str]] = None,
     parameters: Dict[str, str] = None,
+    tags: Union[str, Iterable[str]] = None,
     namespace: str = None,
 ) -> Pipeline:
-    """Create a copy of the pipeline and its nodes,
-    with some dataset names and node names modified.
+    """Create a ``Pipeline`` from a collection of nodes and/or ``Pipeline``s.
 
     Args:
-        pipe: Original modular pipeline to integrate
+        pipe: The nodes the ``Pipeline`` will be made of. If you
+            provide pipelines among the list of nodes, those pipelines will
+            be expanded and all their nodes will become part of this
+            new pipeline.
         inputs: A name or collection of input names to be exposed as connection points
-            to other pipelines upstream.
+            to other pipelines upstream. This is optional; if not provided, the
+            pipeline inputs are automatically inferred from the pipeline structure.
             When str or Set[str] is provided, the listed input names will stay
             the same as they are named in the provided pipeline.
             When Dict[str, str] is provided, current input names will be
             mapped to new names.
             Must only refer to the pipeline's free inputs.
         outputs: A name or collection of names to be exposed as connection points
-            to other pipelines downstream.
+            to other pipelines downstream. This is optional; if not provided, the
+            pipeline inputs are automatically inferred from the pipeline structure.
             When str or Set[str] is provided, the listed output names will stay
             the same as they are named in the provided pipeline.
             When Dict[str, str] is provided, current output names will be
             mapped to new names.
             Can refer to both the pipeline's free outputs, as well as
             intermediate results that need to be exposed.
         parameters: A map of existing parameter to the new one.
+        tags: Optional set of tags to be applied to all the pipeline nodes.
         namespace: A prefix to give to all dataset names,
             except those explicitly named with the `inputs`/`outputs`
             arguments, and parameter references (`params:` and `parameters`).
@@ -108,8 +114,17 @@ def pipeline(
             any of the expected types (str, dict, list, or None).
 
     Returns:
-        A new ``Pipeline`` object with the new nodes, modified as requested.
+        A new ``Pipeline`` object.
     """
+    if isinstance(pipe, Pipeline):
+        # To ensure that we are always dealing with a *copy* of pipe.
+        pipe = Pipeline([pipe], tags=tags)
+    else:
+        pipe = Pipeline(pipe, tags=tags)
+
+    if not any([inputs, outputs, parameters, namespace]):
+        return pipe
+
     # pylint: disable=protected-access
     inputs = _to_dict(inputs)
     outputs = _to_dict(outputs)
@@ -181,7 +196,7 @@ def _copy_node(node: Node) -> Node:
 
     new_nodes = [_copy_node(n) for n in pipe.nodes]
 
-    return Pipeline(new_nodes)
+    return Pipeline(new_nodes, tags=tags)
 
 
 def _to_dict(element: Union[None, str, Set[str], Dict[str, str]]) -> Dict[str, str]:

kedro/pipeline/node.py

@@ -599,7 +599,7 @@ def node(
     outputs: Union[None, str, List[str], Dict[str, str]],
     *,
     name: str = None,
-    tags: Iterable[str] = None,
+    tags: Union[str, Iterable[str]] = None,
     confirms: Union[str, List[str]] = None,
     namespace: str = None,
 ) -> Node:

kedro/pipeline/pipeline.py

@@ -692,10 +692,13 @@ def decorate(self, *decorators: Callable) -> "Pipeline":
         return Pipeline(nodes)
 
     def tag(self, tags: Union[str, Iterable[str]]) -> "Pipeline":
-        """
-        Return a copy of the pipeline, with each node tagged accordingly.
-        :param tags: The tags to be added to the nodes.
-        :return: New `Pipeline` object.
+        """Tags all the nodes in the pipeline.
+
+        Args:
+            tags: The tags to be added to the nodes.
+
+        Returns:
+            New ``Pipeline`` object with nodes tagged.
         """
         nodes = [n.tag(tags) for n in self.nodes]
         return Pipeline(nodes)

kedro/templates/pipeline/{{ cookiecutter.pipeline_name }}/pipeline.py

@@ -3,8 +3,8 @@
 generated using Kedro {{ cookiecutter.kedro_version }}
 """
 
-from kedro.pipeline import Pipeline, node
+from kedro.pipeline import Pipeline, node, pipeline
 
 
-def create_pipeline(**kwargs):
-    return Pipeline([])
+def create_pipeline(**kwargs) -> Pipeline:
+    return pipeline([])

kedro/templates/project/{{ cookiecutter.repo_name }}/src/{{ cookiecutter.python_package }}/pipeline_registry.py

@@ -1,7 +1,7 @@
 """Project pipelines."""
 from typing import Dict
 
-from kedro.pipeline import Pipeline
+from kedro.pipeline import Pipeline, pipeline
 
 
 def register_pipelines() -> Dict[str, Pipeline]:
@@ -10,4 +10,4 @@ def register_pipelines() -> Dict[str, Pipeline]:
     Returns:
         A mapping from a pipeline name to a ``Pipeline`` object.
     """
-    return {"__default__": Pipeline([])}
+    return {"__default__": pipeline([])}

tests/pipeline/test_pipeline_helper.py

@@ -355,3 +355,16 @@ def test_bad_outputs_mapping(self):
         pattern = "Outputs can't contain free inputs to the pipeline"
         with pytest.raises(ModularPipelineError, match=pattern):
             pipeline(raw_pipeline, outputs={"A": "C"})
+
+    def test_pipeline_always_copies(self):
+        original_pipeline = pipeline([node(constant_output, None, "A")])
+        new_pipeline = pipeline(original_pipeline)
+        assert new_pipeline is not original_pipeline
+
+    def test_pipeline_tags(self):
+        tagged_pipeline = pipeline(
+            [node(constant_output, None, "A"), node(constant_output, None, "B")],
+            tags="tag",
+        )
+
+        assert all(n.tags == {"tag"} for n in tagged_pipeline.nodes)