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"""
Example Airflow DAG that starts, stops and sets the machine type of a Google Compute
Engine instance.

This DAG relies on the following OS environment variables

* GCP_PROJECT_ID - Google Cloud Platform project where the Compute Engine instance exists.
* GCE_ZONE - Google Cloud Platform zone where the instance exists.
* GCE_INSTANCE - Name of the Compute Engine instance.
* GCE_SHORT_MACHINE_TYPE_NAME - Machine type resource name to set, e.g. 'n1-standard-1'.
    See https://cloud.google.com/compute/docs/machine-types
"""

import os

from airflow import models
from airflow.providers.google.cloud.operators.compute import (
    ComputeEngineSetMachineTypeOperator, ComputeEngineStartInstanceOperator,
    ComputeEngineStopInstanceOperator,
)
from airflow.utils.dates import days_ago

# [START howto_operator_gce_args_common]
GCP_PROJECT_ID = os.environ.get('GCP_PROJECT_ID', 'example-project')
GCE_ZONE = os.environ.get('GCE_ZONE', 'europe-west1-b')
GCE_INSTANCE = os.environ.get('GCE_INSTANCE', 'testinstance')
# [END howto_operator_gce_args_common]

default_args = {
    'start_date': days_ago(1),
}

# [START howto_operator_gce_args_set_machine_type]
GCE_SHORT_MACHINE_TYPE_NAME = os.environ.get('GCE_SHORT_MACHINE_TYPE_NAME', 'n1-standard-1')
SET_MACHINE_TYPE_BODY = {
    'machineType': 'zones/{}/machineTypes/{}'.format(GCE_ZONE, GCE_SHORT_MACHINE_TYPE_NAME)
}
# [END howto_operator_gce_args_set_machine_type]


with models.DAG(
    'example_gcp_compute',
    default_args=default_args,
    schedule_interval=None,  # Override to match your needs
    tags=['example'],
) as dag:
    # [START howto_operator_gce_start]
    gce_instance_start = ComputeEngineStartInstanceOperator(
        project_id=GCP_PROJECT_ID,
        zone=GCE_ZONE,
        resource_id=GCE_INSTANCE,
        task_id='gcp_compute_start_task'
    )
    # [END howto_operator_gce_start]
    # Duplicate start for idempotence testing
    # [START howto_operator_gce_start_no_project_id]
    gce_instance_start2 = ComputeEngineStartInstanceOperator(
        zone=GCE_ZONE,
        resource_id=GCE_INSTANCE,
        task_id='gcp_compute_start_task2'
    )
    # [END howto_operator_gce_start_no_project_id]
    # [START howto_operator_gce_stop]
    gce_instance_stop = ComputeEngineStopInstanceOperator(
        project_id=GCP_PROJECT_ID,
        zone=GCE_ZONE,
        resource_id=GCE_INSTANCE,
        task_id='gcp_compute_stop_task'
    )
    # [END howto_operator_gce_stop]
    # Duplicate stop for idempotence testing
    # [START howto_operator_gce_stop_no_project_id]
    gce_instance_stop2 = ComputeEngineStopInstanceOperator(
        zone=GCE_ZONE,
        resource_id=GCE_INSTANCE,
        task_id='gcp_compute_stop_task2'
    )
    # [END howto_operator_gce_stop_no_project_id]
    # [START howto_operator_gce_set_machine_type]
    gce_set_machine_type = ComputeEngineSetMachineTypeOperator(
        project_id=GCP_PROJECT_ID,
        zone=GCE_ZONE,
        resource_id=GCE_INSTANCE,
        body=SET_MACHINE_TYPE_BODY,
        task_id='gcp_compute_set_machine_type'
    )
    # [END howto_operator_gce_set_machine_type]
    # Duplicate set machine type for idempotence testing
    # [START howto_operator_gce_set_machine_type_no_project_id]
    gce_set_machine_type2 = ComputeEngineSetMachineTypeOperator(
        zone=GCE_ZONE,
        resource_id=GCE_INSTANCE,
        body=SET_MACHINE_TYPE_BODY,
        task_id='gcp_compute_set_machine_type2'
    )
    # [END howto_operator_gce_set_machine_type_no_project_id]

    gce_instance_start >> gce_instance_start2 >> gce_instance_stop >> \
        gce_instance_stop2 >> gce_set_machine_type >> gce_set_machine_type2
