# Copyright 2016 Google Inc. All Rights Reserved.

#

# 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.

import json

import time

import requests

"""Example of using the Metadata Server to watch deprecated endpoint accesses.

For more information, see the README.md under /compute.

"""

METADATA_URL = 'http://metadata.google.internal/computeMetadata/v1'

METADATA_HEADERS = {'Metadata-Flavor': 'Google'}

# [START compute_wait_for_legacy_usage]

def wait_for_legacy_usage(callback):

url = '{}/instance/legacy-endpoint-access'.format(METADATA_URL)

last_etag = '0'

counts = None

while True:

r = requests.get(

url,

params={

'last_etag': last_etag,

'recursive': True,

'wait_for_change': True

},

headers=METADATA_HEADERS)

if r.status_code == 503: # Metadata server unavailable

print('Metadata server unavailable. Sleeping for 1 second.')

time.sleep(1)

continue

if r.status_code == 404: # Feature not yet supported

print('Legacy endpoint access not supported. Sleeping for 1 hour.')

time.sleep(3600)

continue

r.raise_for_status()

last_etag = r.headers['etag']

access_info = json.loads(r.text)

if not counts:

counts = access_info

if access_info != counts:

diff = {

ver: access_info[ver] - counts[ver] for ver in counts

}

counts = access_info

callback(diff)

# [END compute_wait_for_legacy_usage]

def legacy_callback(diff):

print(

'Since last message, {} new requests to 0.1 endpoints and {} new '

'requests to v1beta1 endpoints.'.format(diff['0.1'], diff['v1beta1']))

def main():

wait_for_legacy_usage(legacy_callback)

if __name__ == '__main__':

main()