chore(sdk.v2): Support explicit task dependency (#4824)

sdk/python/kfp/v2/compiler/compiler.py

@@ -93,6 +93,11 @@ class Compiler(object):
       deployment_config.executors[task.executor_label].container.CopyFrom(
           op.container_spec)
 
+      # A task may have explicit depdency on other tasks even though they may
+      # not have inputs/outputs dependency. e.g.: op2.after(op1)
+      if op.dependent_names:
+        task.dependent_tasks.extend(op.dependent_names)
+
       # Check if need to insert importer node
       for input_name in task.inputs.artifacts:
         if not task.inputs.artifacts[input_name].producer_task:

sdk/python/kfp/v2/compiler_cli_tests/compiler_cli_tests.py

@@ -75,5 +75,9 @@ class CompilerCliTests(unittest.TestCase):
   def test_pipeline_with_reused_component(self):
     self._test_compile_py_to_json('pipeline_with_reused_component')
 
+  def test_pipeline_with_after(self):
+    self._test_compile_py_to_json('pipeline_with_after')
+
+
 if __name__ == '__main__':
   unittest.main()

sdk/python/kfp/v2/compiler_cli_tests/test_data/pipeline_with_after.json

@@ -0,0 +1,110 @@
+{
+  "pipelineSpec": {
+    "deploymentConfig": {
+      "@type": "type.googleapis.com/ml_pipelines.PipelineDeploymentConfig",
+      "executors": {
+        "Print Text": {
+          "container": {
+            "command": [
+              "sh",
+              "-c",
+              "set -e -x\necho \"$0\"\n",
+              "{{$.inputs.parameters['text']}}"
+            ],
+            "image": "alpine"
+          }
+        },
+        "Print Text 3": {
+          "container": {
+            "image": "alpine",
+            "command": [
+              "sh",
+              "-c",
+              "set -e -x\necho \"$0\"\n",
+              "{{$.inputs.parameters['text']}}"
+            ]
+          }
+        },
+        "Print Text 2": {
+          "container": {
+            "command": [
+              "sh",
+              "-c",
+              "set -e -x\necho \"$0\"\n",
+              "{{$.inputs.parameters['text']}}"
+            ],
+            "image": "alpine"
+          }
+        }
+      }
+    },
+    "pipelineInfo": {
+      "name": "pipeline-with-after"
+    },
+    "sdkVersion": "kfp-1.1.1",
+    "tasks": [
+      {
+        "executorLabel": "Print Text",
+        "taskInfo": {
+          "name": "Print Text"
+        },
+        "inputs": {
+          "parameters": {
+            "text": {
+              "runtimeValue": {
+                "constantValue": {
+                  "stringValue": "1st task"
+                }
+              }
+            }
+          }
+        }
+      },
+      {
+        "inputs": {
+          "parameters": {
+            "text": {
+              "runtimeValue": {
+                "constantValue": {
+                  "stringValue": "2nd task"
+                }
+              }
+            }
+          }
+        },
+        "dependentTasks": [
+          "Print Text"
+        ],
+        "taskInfo": {
+          "name": "Print Text 2"
+        },
+        "executorLabel": "Print Text 2"
+      },
+      {
+        "dependentTasks": [
+          "Print Text",
+          "Print Text 2"
+        ],
+        "inputs": {
+          "parameters": {
+            "text": {
+              "runtimeValue": {
+                "constantValue": {
+                  "stringValue": "3rd task"
+                }
+              }
+            }
+          }
+        },
+        "executorLabel": "Print Text 3",
+        "taskInfo": {
+          "name": "Print Text 3"
+        }
+      }
+    ],
+    "schemaVersion": "v2alpha1"
+  },
+  "runtimeConfig": {
+    "gcsOutputDirectory": "dummy_root"
+  }
+}

sdk/python/kfp/v2/compiler_cli_tests/test_data/pipeline_with_after.py

@@ -0,0 +1,47 @@
+# Copyright 2020 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from kfp.v2 import components
+from kfp.v2 import dsl
+import kfp.v2.compiler as compiler
+
+component_op = components.load_component_from_text("""
+name: Print Text
+inputs:
+- {name: text, type: String}
+implementation:
+  container:
+    image: alpine
+    command:
+    - sh
+    - -c
+    - |
+      set -e -x
+      echo "$0"
+    - {inputValue: text}
+""")
+
+
+@dsl.pipeline(name='pipeline-with-after')
+def my_pipeline():
+  task1 = component_op(text='1st task')
+  task2 = component_op(text='2nd task').after(task1)
+  task3 = component_op(text='3rd task').after(task1, task2)
+
+
+if __name__ == '__main__':
+  compiler.Compiler().compile(
+      pipeline_func=my_pipeline,
+      pipeline_root='dummy_root',
+      output_path=__file__ + '.json')