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"""
Example Airflow DAG that displays interactions with Google Cloud Functions.
It creates a function and then deletes it.

This DAG relies on the following OS environment variables
https://airflow.apache.org/concepts.html#variables
* GCP_PROJECT_ID - Google Cloud Project to use for the Cloud Function.
* GCP_LOCATION - Google Cloud Functions region where the function should be
  created.
* GCF_ENTRYPOINT - Name of the executable function in the source code.
* and one of the below:
    - GCF_SOURCE_ARCHIVE_URL - Path to the zipped source in Google Cloud Storage
    or
    (
        - GCF_SOURCE_UPLOAD_URL - Generated upload URL for the zipped source
        and
        - GCF_ZIP_PATH - Local path to the zipped source archive
    )
    or
    - GCF_SOURCE_REPOSITORY - The URL pointing to the hosted repository where the function
    is defined in a supported Cloud Source Repository URL format
    https://cloud.google.com/functions/docs/reference/rest/v1/projects.locations.functions#SourceRepository
"""

import os

from airflow import models
from airflow.contrib.operators.gcp_function_operator \
    import GcfFunctionDeployOperator, GcfFunctionDeleteOperator
from airflow.utils import dates

# [START howto_operator_gcf_common_variables]
GCP_PROJECT_ID = os.environ.get('GCP_PROJECT_ID', 'example-project')
GCP_LOCATION = os.environ.get('GCP_LOCATION', 'europe-west1')
GCF_SHORT_FUNCTION_NAME = os.environ.get('GCF_SHORT_FUNCTION_NAME', 'hello').\
    replace("-", "_")  # make sure there are no dashes in function name (!)
FUNCTION_NAME = 'projects/{}/locations/{}/functions/{}'.format(GCP_PROJECT_ID,
                                                               GCP_LOCATION,
                                                               GCF_SHORT_FUNCTION_NAME)
# [END howto_operator_gcf_common_variables]
# [START howto_operator_gcf_deploy_variables]
GCF_SOURCE_ARCHIVE_URL = os.environ.get('GCF_SOURCE_ARCHIVE_URL', '')
GCF_SOURCE_UPLOAD_URL = os.environ.get('GCF_SOURCE_UPLOAD_URL', '')
GCF_SOURCE_REPOSITORY = os.environ.get(
    'GCF_SOURCE_REPOSITORY',
    'https://source.developers.google.com/'
    'projects/{}/repos/hello-world/moveable-aliases/master'.format(GCP_PROJECT_ID))
GCF_ZIP_PATH = os.environ.get('GCF_ZIP_PATH', '')
GCF_ENTRYPOINT = os.environ.get('GCF_ENTRYPOINT', 'helloWorld')
GCF_RUNTIME = 'nodejs6'
GCP_VALIDATE_BODY = os.environ.get('GCP_VALIDATE_BODY', True)
# [END howto_operator_gcf_deploy_variables]

# [START howto_operator_gcf_deploy_body]
body = {
    "name": FUNCTION_NAME,
    "entryPoint": GCF_ENTRYPOINT,
    "runtime": GCF_RUNTIME,
    "httpsTrigger": {}
}
# [END howto_operator_gcf_deploy_body]

# [START howto_operator_gcf_default_args]
default_args = {
    'start_date': dates.days_ago(1)
}
# [END howto_operator_gcf_default_args]

# [START howto_operator_gcf_deploy_variants]
if GCF_SOURCE_ARCHIVE_URL:
    body['sourceArchiveUrl'] = GCF_SOURCE_ARCHIVE_URL
elif GCF_SOURCE_REPOSITORY:
    body['sourceRepository'] = {
        'url': GCF_SOURCE_REPOSITORY
    }
elif GCF_ZIP_PATH:
    body['sourceUploadUrl'] = ''
    default_args['zip_path'] = GCF_ZIP_PATH
elif GCF_SOURCE_UPLOAD_URL:
    body['sourceUploadUrl'] = GCF_SOURCE_UPLOAD_URL
else:
    raise Exception("Please provide one of the source_code parameters")
# [END howto_operator_gcf_deploy_variants]


with models.DAG(
    'example_gcp_function',
    default_args=default_args,
    schedule_interval=None  # Override to match your needs
) as dag:
    # [START howto_operator_gcf_deploy]
    deploy_task = GcfFunctionDeployOperator(
        task_id="gcf_deploy_task",
        project_id=GCP_PROJECT_ID,
        location=GCP_LOCATION,
        body=body,
        validate_body=GCP_VALIDATE_BODY
    )
    # [END howto_operator_gcf_deploy]
    # [START howto_operator_gcf_deploy_no_project_id]
    deploy2_task = GcfFunctionDeployOperator(
        task_id="gcf_deploy2_task",
        location=GCP_LOCATION,
        body=body,
        validate_body=GCP_VALIDATE_BODY
    )
    # [END howto_operator_gcf_deploy_no_project_id]
    # [START howto_operator_gcf_delete]
    delete_task = GcfFunctionDeleteOperator(
        task_id="gcf_delete_task",
        name=FUNCTION_NAME
    )
    # [END howto_operator_gcf_delete]
    deploy_task >> deploy2_task >> delete_task
