kuryr-kubernetes/kuryr_kubernetes/k8s_client.py

# Copyright (c) 2016 Mirantis, 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 contextlib
import itertools

from oslo_log import log as logging
from oslo_serialization import jsonutils
import requests

from kuryr_kubernetes import exceptions as exc

LOG = logging.getLogger(__name__)


class K8sClient(object):
    # REVISIT(ivc): replace with python-k8sclient if it could be extended
    # with 'WATCH' support

    def __init__(self, base_url):
        self._base_url = base_url

    def get(self, path):
        LOG.debug("Get %(path)s", {'path': path})
        url = self._base_url + path
        response = requests.get(url)
        if not response.ok:
            raise exc.K8sClientException(response.text)
        return response.json()

    def annotate(self, path, annotations, resource_version=None):
        """Pushes a resource annotation to the K8s API resource

        The annotate operation is made with a PATCH HTTP request of kind:
        application/merge-patch+json as described in:

        https://github.com/kubernetes/community/blob/master/contributors/devel/api-conventions.md#patch-operations  # noqa
        """
        LOG.debug("Annotate %(path)s: %(names)s", {
            'path': path, 'names': list(annotations)})
        url = self._base_url + path
        while itertools.count(1):
            data = jsonutils.dumps({
                "metadata": {
                    "annotations": annotations,
                    "resourceVersion": resource_version,
                }
            }, sort_keys=True)
            response = requests.patch(url, data=data, headers={
                'Content-Type': 'application/merge-patch+json',
                'Accept': 'application/json',
            })
            if response.ok:
                return response.json()['metadata']['annotations']
            if response.status_code == requests.codes.conflict:
                resource = self.get(path)
                new_version = resource['metadata']['resourceVersion']
                retrieved_annotations = resource['metadata'].get(
                    'annotations', {})

                for k, v in annotations.items():
                    if v != retrieved_annotations.get(k, v):
                        break
                else:
                    # No conflicting annotations found. Retry patching
                    resource_version = new_version
                    continue
                LOG.debug("Annotations for %(path)s already present: "
                          "%(names)s", {'path': path,
                                        'names': retrieved_annotations})
            raise exc.K8sClientException(response.text)

    def watch(self, path):
        params = {'watch': 'true'}
        url = self._base_url + path

        # TODO(ivc): handle connection errors and retry on failure
        while True:
            with contextlib.closing(requests.get(url, params=params,
                                                 stream=True)) as response:
                if not response.ok:
                    raise exc.K8sClientException(response.text)
                for line in response.iter_lines(delimiter='\n'):
                    line = line.strip()
                    if line:
                        yield jsonutils.loads(line)