interface.py 8.61 KB
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# Copyright (c) 2017, Daniele Venzano
#
# 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.

"""The high-level interface that Zoe uses to talk to the configured container backend."""

import logging
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import time
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from typing import List
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from zoe_lib.config import get_conf
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from zoe_lib.state import Execution, Service, SQLManager  # pylint: disable=unused-import
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from zoe_master.backends.base import BaseBackend
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from zoe_master.backends.service_instance import ServiceInstance
from zoe_master.exceptions import ZoeStartExecutionFatalException, ZoeStartExecutionRetryException, ZoeException
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from zoe_master.stats import ClusterStats, NodeStats  # pylint: disable=unused-import
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try:
    from zoe_master.backends.swarm.backend import SwarmBackend
except ImportError as ex:
    SwarmBackend = None

try:
    from zoe_master.backends.kubernetes.backend import KubernetesBackend
except ImportError:
    KubernetesBackend = None
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try:
    from zoe_master.backends.docker.backend import DockerEngineBackend
except ImportError:
    DockerEngineBackend = None

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log = logging.getLogger(__name__)


def _get_backend() -> BaseBackend:
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    """Return the right backend instance by reading the global configuration."""
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    backend_name = get_conf().backend
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    if backend_name == 'Kubernetes':
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        if KubernetesBackend is None:
            raise ZoeException('The Kubernetes backend requires the pykube module')
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        return KubernetesBackend(get_conf())
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    elif backend_name == 'Swarm':
        if SwarmBackend is None:
            raise ZoeException('The Swarm backend requires docker python version >= 2.0.2')
        return SwarmBackend(get_conf())
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    elif backend_name == 'DockerEngine':
        if DockerEngineBackend is None:
            raise ZoeException('The Docker Engine backend requires docker python version >= 2.0.2')
        return DockerEngineBackend(get_conf())
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    else:
        log.error('Unknown backend selected')
        assert False


def initialize_backend(state):
    """Initializes the configured backend."""
    backend = _get_backend()
    backend.init(state)


def shutdown_backend():
    """Shuts down the configured backend."""
    backend = _get_backend()
    backend.shutdown()


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def service_list_to_containers(execution: Execution, service_list: List[Service], placement=None) -> str:
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    """Given a subset of services from an execution, tries to start them, return one of 'ok', 'requeue' for temporary failures and 'fatal' for fatal failures."""
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    backend = _get_backend()

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    ordered_service_list = sorted(service_list, key=lambda x: x.startup_order)
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    env_subst_dict = {
        'execution_id': execution.id,
        "execution_name": execution.name,
        'user_name': execution.user_id,
        'deployment_name': get_conf().deployment_name,
    }

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    for service in execution.services:
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        env_subst_dict['dns_name#' + service.name] = service.dns_name

    for service in ordered_service_list:
        env_subst_dict['dns_name#self'] = service.dns_name
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        if placement is not None:
            service.assign_backend_host(placement[service.id])
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        service.set_starting()
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        instance = ServiceInstance(execution, service, env_subst_dict)
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        try:
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            backend_id, ip_address, ports = backend.spawn_service(instance)
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        except ZoeStartExecutionRetryException as ex:
            log.warning('Temporary failure starting service {} of execution {}: {}'.format(service.id, execution.id, ex.message))
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            service.set_error(ex.message)
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            execution.set_error_message(ex.message)
            terminate_execution(execution)
            execution.set_scheduled()
            return "requeue"
        except ZoeStartExecutionFatalException as ex:
            log.error('Fatal error trying to start service {} of execution {}: {}'.format(service.id, execution.id, ex.message))
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            service.set_error(ex.message)
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            execution.set_error_message(ex.message)
            terminate_execution(execution)
            execution.set_error()
            return "fatal"
        except Exception as ex:
            log.error('Fatal error trying to start service {} of execution {}'.format(service.id, execution.id))
            log.exception('BUG, this error should have been caught earlier')
            execution.set_error_message(str(ex))
            terminate_execution(execution)
            execution.set_error()
            return "fatal"
        else:
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            log.debug('Service {} started'.format(instance.name))
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            service.set_active(backend_id, ip_address, ports)
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    return "ok"
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def start_all(execution: Execution) -> str:
    """Translate an execution object into containers.

    If an error occurs some containers may have been created and needs to be cleaned-up.
    """
    log.debug('starting all services for execution {}'.format(execution.id))
    execution.set_starting()
    return service_list_to_containers(execution, execution.services)


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def start_essential(execution: Execution, placement) -> str:
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    """Start the essential services for this execution"""
    log.debug('starting essential services for execution {}'.format(execution.id))
    execution.set_starting()

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    return service_list_to_containers(execution, execution.essential_services, placement)
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def start_elastic(execution: Execution, placement) -> str:
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    """Start the runnable elastic services"""
    elastic_to_start = [s for s in execution.elastic_services if s.status == Service.RUNNABLE_STATUS]
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    return service_list_to_containers(execution, elastic_to_start, placement)
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def terminate_execution(execution: Execution) -> None:
    """Terminate an execution."""
    backend = _get_backend()
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    for service in execution.services:  # type: Service
        if service.status != Service.INACTIVE_STATUS:
            if service.status == Service.ERROR_STATUS:
                continue
            elif service.status == Service.ACTIVE_STATUS or service.status == Service.TERMINATING_STATUS or service.status == Service.STARTING_STATUS:
                service.set_terminating()
                backend.terminate_service(service)
                service.set_inactive()
                log.debug('Service {} terminated'.format(service.name))
            elif service.status == Service.CREATED_STATUS or service.status == Service.RUNNABLE_STATUS:
                service.set_inactive()
            else:
                log.error('BUG: don\'t know how to terminate a service in status {}'.format(service.status))
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        elif not service.is_dead():
            log.warning('Service {} is inactive for Zoe, but running for the back-end, terminating and resetting state'.format(service.name))
            service.set_terminating()
            backend.terminate_service(service)
            service.set_inactive()
            log.debug('Service {} terminated'.format(service.name))
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    execution.set_terminated()
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CACHED_STATS = None  # type: ClusterStats


def get_platform_state(state: SQLManager, force_update=False) -> ClusterStats:
    """Retrieves the state of the platform by querying the container backend. Platform state includes information on free/reserved resources for each node. This information is used for advanced scheduling.
    Since retrieving statistics can be slow, the we cache results and use the force_update parameter to know when fresh (and slow) values are absolutely needed."""
    global CACHED_STATS

    if CACHED_STATS is not None and not force_update:
        return CACHED_STATS

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    backend = _get_backend()
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    platform_state = backend.platform_state()
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    for node in platform_state.nodes:  # type: NodeStats
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        node.services = state.service_list(backend_host=node.name, backend_status=Service.BACKEND_START_STATUS)
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    CACHED_STATS = platform_state
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    return platform_state
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def preload_image(image_name):
    """Make a service image available on the cluster, according to the backend support."""
    backend = _get_backend()
    log.debug('Preloading image {}'.format(image_name))
    time_start = time.time()
    try:
        backend.preload_image(image_name)
        log.info('Image {} preloaded in {:.2f}s'.format(image_name, time.time() - time_start))
    except NotImplementedError:
        log.warning('Backend {} does not support image preloading'.format(get_conf().backend))