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# ============LICENSE_START=======================================================
# org.onap.dcae
# ================================================================================
# Copyright (c) 2017 AT&T Intellectual Property. 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.
# ============LICENSE_END=========================================================
#
# ECOMP is a trademark and service mark of AT&T Intellectual Property.
from functools import partial
import json
import logging
import uuid
import requests
import consul
logger = logging.getLogger("discovery")
class DiscoveryError(RuntimeError):
pass
class DiscoveryConnectionError(RuntimeError):
pass
class DiscoveryServiceNotFoundError(RuntimeError):
pass
def _wrap_consul_call(consul_func, *args, **kwargs):
"""Wrap Consul call to map errors"""
try:
return consul_func(*args, **kwargs)
except requests.exceptions.ConnectionError as e:
raise DiscoveryConnectionError(e)
def generate_service_component_name(service_component_type, service_id, location_id):
"""Generate service component id used to pass into the service component
instance and used as the key to the service component configuration.
Format:
<service component id>.<service component type>.<service id>.<location id>.dcae.com
TODO: The format will evolve.
"""
# Random generated
service_component_id = str(uuid.uuid4())
return "{0}.{1}.{2}.{3}.dcae.com".format(
service_component_id, service_component_type, service_id, location_id)
def create_kv_conn(host):
"""Create connection to key-value store
Returns a Consul client to the specified Consul host"""
try:
[hostname, port] = host.split(":")
return consul.Consul(host=hostname, port=int(port))
except ValueError as e:
return consul.Consul(host=host)
def push_service_component_config(kv_conn, service_component_name, config):
config_string = config if isinstance(config, str) else json.dumps(config)
kv_put_func = partial(_wrap_consul_call, kv_conn.kv.put)
if kv_put_func(service_component_name, config_string):
logger.info("Added config for {0}".format(service_component_name))
else:
raise DiscoveryError("Failed to push configuration")
def remove_service_component_config(kv_conn, service_component_name):
kv_delete_func = partial(_wrap_consul_call, kv_conn.kv.delete)
kv_delete_func(service_component_name)
def _create_rel_key(service_component_name):
return "{0}:rel".format(service_component_name)
def store_relationship(kv_conn, source_name, target_name):
# TODO: Rel entry may already exist in a one-to-many situation. Need to
# support that.
rel_key = _create_rel_key(source_name)
rel_value = [target_name] if target_name else []
kv_put_func = partial(_wrap_consul_call, kv_conn.kv.put)
kv_put_func(rel_key, json.dumps(rel_value))
logger.info("Added relationship for {0}".format(rel_key))
def delete_relationship(kv_conn, service_component_name):
rel_key = _create_rel_key(service_component_name)
kv_get_func = partial(_wrap_consul_call, kv_conn.kv.get)
index, rels = kv_get_func(rel_key)
if rels:
rels = json.loads(rels["Value"].decode("utf-8"))
kv_delete_func = partial(_wrap_consul_call, kv_conn.kv.delete)
kv_delete_func(rel_key)
return rels
else:
return []
def lookup_service(kv_conn, service_component_name):
catalog_get_func = partial(_wrap_consul_call, kv_conn.catalog.service)
index, results = catalog_get_func(service_component_name)
if results:
return results
else:
raise DiscoveryServiceNotFoundError("Failed to find: {0}".format(service_component_name))
# TODO: Note these functions have been (for the most part) shamelessly lifted from
# dcae-cli and should really be shared.
def _is_healthy_pure(get_health_func, instance):
"""Checks to see if a component instance is running healthy
Pure function edition
Args
----
get_health_func: func(string) -> complex object
Look at unittests in test_discovery to see examples
instance: (string) fully qualified name of component instance
Returns
-------
True if instance has been found and is healthy else False
"""
index, resp = get_health_func(instance)
if resp:
def is_passing(instance):
return all([check["Status"] == "passing" for check in instance["Checks"]])
return any([is_passing(instance) for instance in resp])
else:
return False
def is_healthy(consul_host, instance):
"""Checks to see if a component instance is running healthy
Impure function edition
Args
----
consul_host: (string) host string of Consul
instance: (string) fully qualified name of component instance
Returns
-------
True if instance has been found and is healthy else False
"""
cons = create_kv_conn(consul_host)
get_health_func = partial(_wrap_consul_call, cons.health.service)
return _is_healthy_pure(get_health_func, instance)
def add_to_entry(conn, key, add_name, add_value):
"""
Find 'key' in consul.
Treat its value as a JSON string representing a dict.
Extend the dict by adding an entry with key 'add_name' and value 'add_value'.
Turn the resulting extended dict into a JSON string.
Store the string back into Consul under 'key'.
Watch out for conflicting concurrent updates.
Example:
Key 'xyz:dmaap' has the value '{"feed00": {"feed_url" : "http://example.com/feeds/999"}}'
add_to_entry('xyz:dmaap', 'topic00', {'topic_url' : 'http://example.com/topics/1229'})
should result in the value for key 'xyz:dmaap' in consul being updated to
'{"feed00": {"feed_url" : "http://example.com/feeds/999"}, "topic00" : {"topic_url" : "http://example.com/topics/1229"}}'
"""
while True: # do until update succeeds
(index, val) = conn.kv.get(key) # index gives version of key retrieved
if val is None: # no key yet
vstring = '{}'
mod_index = 0 # Use 0 as the cas index for initial insertion of the key
else:
vstring = val['Value']
mod_index = val['ModifyIndex']
# Build the updated dict
# Exceptions just propagate
v = json.loads(vstring)
v[add_name] = add_value
new_vstring = json.dumps(v)
updated = conn.kv.put(key, new_vstring, cas=mod_index) # if the key has changed since retrieval, this will return false
if updated:
return v
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