Add Python dependencies example workflow. (GoogleCloudPlatform#1576)

* Add Python dependencies example workflow.

* Move dependencies example to workflows folder and add tests

Updates sample to use relative imports.

Adds license headers.

Uses 4 spaces for indentation.

* Add region tag for local deps sample.

* Rename local deps sample for better explaination in the docs.

* Rename to coin_module to reflect correct Python term.

Author: Crystal Qian

composer/workflows/README.rst

@@ -0,0 +1,63 @@
+.. This file is automatically generated. Do not edit this file directly.
+
+Google Cloud Composer Python Samples
+===============================================================================
+
+.. image:: https://gstatic.com/cloudssh/images/open-btn.png
+   :target: https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/GoogleCloudPlatform/python-docs-samples&page=editor&open_in_editor=composer/workflows/README.rst
+
+
+This directory contains samples for Google Cloud Composer. `Google Cloud Composer`_ is a fully managed workflow orchestration service built on Apache Airflow.
+
+
+
+
+.. _Google Cloud Composer: https://cloud.google.com/composer/docs
+
+Setup
+-------------------------------------------------------------------------------
+
+
+Authentication
+++++++++++++++
+
+This sample requires you to have authentication setup. Refer to the
+`Authentication Getting Started Guide`_ for instructions on setting up
+credentials for applications.
+
+.. _Authentication Getting Started Guide:
+    https://cloud.google.com/docs/authentication/getting-started
+
+Install Dependencies
+++++++++++++++++++++
+
+#. Clone python-docs-samples and change directory to the sample directory you want to use.
+
+    .. code-block:: bash
+
+        $ git clone https://github.com/GoogleCloudPlatform/python-docs-samples.git
+
+#. Install `pip`_ and `virtualenv`_ if you do not already have them. You may want to refer to the `Python Development Environment Setup Guide`_ for Google Cloud Platform for instructions.
+
+   .. _Python Development Environment Setup Guide:
+       https://cloud.google.com/python/setup
+
+#. Create a virtualenv. Samples are compatible with Python 2.7 and 3.4+.
+
+    .. code-block:: bash
+
+        $ virtualenv env
+        $ source env/bin/activate
+
+#. Install the dependencies needed to run the samples.
+
+    .. code-block:: bash
+
+        $ pip install -r requirements.txt
+
+.. _pip: https://pip.pypa.io/
+.. _virtualenv: https://virtualenv.pypa.io/
+
+
+
+.. _Google Cloud SDK: https://cloud.google.com/sdk/

composer/workflows/README.rst.in

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+# This file is used to generate README.rst
+
+product:
+  name: Google Cloud Composer
+  short_name: Cloud Composer
+  url: https://cloud.google.com/composer/docs
+  description: >
+    `Google Cloud Composer`_ is a fully managed workflow orchestration
+    service built on Apache Airflow.
+
+setup:
+- auth
+- install_deps
+
+folder: composer/workflows

composer/workflows/dependencies/__init__.py

@@ -0,0 +1,32 @@
+# Copyright 2018 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
+#
+#     https://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.
+
+"""A custom Python package example.
+
+This package requires that your environment has the scipy PyPI package
+installed. """
+
+import numpy as np  # numpy is installed by default in Composer.
+from scipy import special  # scipy is not.
+
+
+def flip_coin():
+    """Return "Heads" or "Tails" depending on a calculation."""
+    # Returns a 2x2 randomly sampled array of values in the range [-5, 5]
+    rand_array = 10 * np.random.random((2, 2)) - 5
+    # Computes the average of this
+    avg = rand_array.mean()
+    # Returns the Gaussian CDF of this average
+    ndtr = special.ndtr(avg)
+    return "Heads" if ndtr > .5 else "Tails"

composer/workflows/dependencies/coin_module.py

@@ -1 +1,3 @@
-https://dist.apache.org/repos/dist/dev/incubator/airflow/1.10.0beta1/apache-airflow-1.10.0b1+incubating.tar.gz#egg=apache-airflow[gcp_api]
+https://dist.apache.org/repos/dist/dev/incubator/airflow/1.10.0rc2/apache-airflow-1.10.0rc2+incubating-bin.tar.gz#egg=apache-airflow[gcp_api]
+scipy==1.1.0
+numpy==1.14.2

composer/workflows/requirements.txt

@@ -0,0 +1,37 @@
+# Copyright 2018 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
+#
+#     https://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.
+
+"""A DAG consisting of a BashOperator that prints the result of a coin flip."""
+
+import datetime
+
+import airflow
+from airflow.operators import bash_operator
+
+# [START composer_dag_local_deps]
+from .dependencies import coin_module
+# [END composer_dag_local_deps]
+
+default_args = {
+    'start_date':
+        datetime.datetime.combine(
+            datetime.datetime.today() - datetime.timedelta(days=1),
+            datetime.datetime.min.time()),
+}
+
+with airflow.DAG('dependencies_dag', default_args=default_args) as dag:
+    t1 = bash_operator.BashOperator(
+        task_id='print_coin_result',
+        bash_command='echo "{0}"'.format(coin_module.flip_coin()),
+        dag=dag)

composer/workflows/use_local_deps.py

@@ -0,0 +1,23 @@
+# Copyright 2018 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
+#
+#     https://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.
+
+
+def test_dag_import():
+    """Test that the DAG file can be successfully imported.
+
+    This tests that the DAG can be parsed, but does not run it in an Airflow
+    environment. This is a recommended sanity check by the official Airflow
+    docs: https://airflow.incubator.apache.org/tutorial.html#testing
+    """
+    from . import use_local_deps # noqa