Intiial utils push to ONAP

Issue-Id: DCAEGEN2-80
Change-Id: I1dc8f2d384b0af346fccb86e6767b7e3ca484078
Signed-off-by: Tommy Carpenter <tommy@research.att.com>

3 files changed, 467 insertions, 0 deletions

diff --git a/python-discovery-client/discovery_client/__init__.py b/python-discovery-client/discovery_client/__init__.py
new file mode 100644
index 0000000..9e0358a
--- /dev/null
+++ b/python-discovery-client/discovery_client/__init__.py
@@ -0,0 +1,21 @@
+# 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 .discovery import get_service_name, get_configuration, \
+    register_for_discovery, resolve_name
diff --git a/python-discovery-client/discovery_client/discovery.py b/python-discovery-client/discovery_client/discovery.py
new file mode 100644
index 0000000..180e933
--- /dev/null
+++ b/python-discovery-client/discovery_client/discovery.py
@@ -0,0 +1,368 @@
+# 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.
+
+import time, json, os, re, logging
+from itertools import chain
+from functools import partial
+import requests
+import consul
+import six
+from discovery_client import util
+
+
+_logger = util.get_logger(__name__)
+
+class DiscoveryInitError(RuntimeError):
+    pass
+
+class DiscoveryRegistrationError(RuntimeError):
+    pass
+
+class DiscoveryResolvingNameError(RuntimeError):
+    pass
+
+
+#####
+# Consul calls for services
+#####
+
+def _get_configuration_from_consul(consul_handle, service_name):
+    index = None
+    while True:
+        index, data = consul_handle.kv.get(service_name, index=index)
+
+        if data:
+            return json.loads(data["Value"].decode("utf-8"))
+        else:
+            _logger.warn("No configuration found for {0}. Try again in a bit."
+                    .format(service_name))
+            time.sleep(5)
+
+def _get_relationships_from_consul(consul_handle, service_name):
+    """Fetch the relationship information from Consul for a service by service
+    name.  Returns a list of service names."""
+    index = None
+    rel_key = "{0}:rel".format(service_name)
+    while True:
+        index, data = consul_handle.kv.get(rel_key, index=index)
+
+        if data:
+            return json.loads(data["Value"].decode("utf-8"))
+        else:
+            _logger.warn("No relationships found for {0}. Try again in a bit."
+                    .format(service_name))
+            time.sleep(5)
+
+def _lookup_with_consul(consul_handle, service_name, max_attempts=0):
+    num_attempts = 1
+
+    while True:
+        index, results = consul_handle.catalog.service(service_name)
+
+        if results:
+            return results
+        else:
+            num_attempts += 1
+
+            if max_attempts > 0 and max_attempts < num_attempts:
+                return None
+
+            _logger.warn("Service not found {0}. Trying again in a bit."
+                    .format(service_name))
+            time.sleep(5)
+
+def _register_with_consul(consul_handle, service_name, service_ip, service_port,
+        health_endpoint):
+    # https://www.consul.io/docs/agent/http/agent.html#agent_service_register
+    # Note: Unhealthy services should not return in queries i.e.
+    # dig @127.0.0.1 -p 8600 foo.service.consul
+    health_url = "http://{0}:{1}/{2}".format(service_ip, service_port, health_endpoint)
+    return consul_handle.agent.service.register(service_name, address=service_ip,
+            port=service_port, check= { "HTTP": health_url, "Interval": "5s" })
+
+#####
+# Config binding service call
+#####
+
+def _get_configuration_resolved_from_cbs(consul_handle, service_name):
+    """
+    This is what a minimal python client library that wraps the CBS would look like.
+    POSSIBLE TODO: break this out into pypi repo
+
+    This call does not raise an exception if Consul or the CBS cannot complete the request.
+    It logs an error and returns {} if the config is not bindable. 
+    It could be a temporary network outage. Call me again later. 
+
+    It will raise an exception if the necessary env parameters were not set because that is irrecoverable.
+    This function is called in my /heatlhcheck, so this will be caught early.
+    """
+    config = {}
+
+    results = _lookup_with_consul(consul_handle, "config_binding_service",
+            max_attempts=5)
+
+    if results is None:
+        logger.error("Cannot bind config at this time, cbs is unreachable")
+    else:
+        cbs_hostname = results[0]["ServiceAddress"]
+        cbs_port = results[0]["ServicePort"]
+        cbs_url = "http://{hostname}:{port}".format(hostname=cbs_hostname, port=cbs_port)
+
+        #get my config
+        my_config_endpoint = "{0}/service_component/{1}".format(cbs_url,
+                service_name)
+        res = requests.get(my_config_endpoint)
+        try:
+            res.raise_for_status()
+            config = res.json()
+            _logger.info("get_config returned the following configuration: {0}".format(json.dumps(config)))
+        except:
+            _logger.error("in get_config, the config binding service endpoint {0} blew up on me. Error code: {1}, Error text: {2}".format(my_config_endpoint, res.status_code, res.text))
+    return config
+
+#####
+# Functionality for putting together service's configuration
+#####
+
+def _get_connection_types(config):
+    """Get all the connection types for a given configuration json
+
+    Crawls through the entire config dict recursively and returns the entries
+    that have been identified as service connections in the form of a list of tuples -
+
+        [(config key, component type), ..]
+
+    where "config key" is a compound key in the form of a tuple. Each entry in
+    the compound key is a key to a level within the json data structure."""
+    def grab_component_type(v):
+        # To support Python2, unicode strings are not type `str`. Specifically,
+        # the config string values from Consul maybe encoded to utf-8 so better
+        # be prepared.
+        if isinstance(v, six.string_types):
+            # Regex matches on strings like "{{foo}}" and "{{ BAR }}" and
+            # extracts the alphanumeric string inside the parantheses.
+            result = re.match("^{{\s*([-_.\w]*)\s*}}", v)
+            return result.group(1) if result else None
+
+    def crawl(config, parent_key=()):
+        if isinstance(config, dict):
+            rels = [ crawl(value, parent_key + (key, ))
+                    for key, value in config.items() ]
+            rels = chain(*rels)
+        elif isinstance(config, list):
+            rels = [ crawl(config[index], parent_key + (index, ))
+                    for index in range(0, len(config)) ]
+            rels = chain(*rels)
+        else:
+            rels = [(parent_key, grab_component_type(config))]
+
+        # Filter out the entries with Nones
+        rels = [(key, rel) for key, rel in rels if rel]
+        return rels
+
+    return crawl(config)
+
+def _has_connections(config):
+    return True if _get_connection_types(config) else False
+
+def _resolve_connection_types(service_name, connection_types, relationships):
+
+    def find_match(connection_type):
+        ret_list = []
+        for rel in relationships:
+            if connection_type in rel:
+                ret_list.append(rel)
+        return ret_list
+
+    return [ (key, find_match(connection_type))
+            for key, connection_type in connection_types ]
+
+def _resolve_name(lookup_func, service_name):
+    """Resolves the service component name to detailed connection information
+
+    Currently this is grouped into two ways:
+    1. CDAP applications take a two step approach - call Consul then call the
+    CDAP broker
+    2. All other applications just call Consul to get IP and port
+
+    Args:
+    ----
+    lookup_func: fn(string) -> list of dicts
+        The function should return a list of dicts that have "ServiceAddress" and
+        "ServicePort" key value entries
+    service_name: (string) service name to lookup
+
+    Return depends upon the connection type:
+    1. CDAP applications return a dict
+    2. All other applications return a string
+    """
+    def handle_result(result):
+        ip = result["ServiceAddress"]
+        port = result["ServicePort"]
+
+        if not (ip and port):
+            raise DiscoveryResolvingNameError(
+                    "Failed to resolve name for {0}: ip, port not set".format(service_name))
+
+        # TODO: Need a better way to identify CDAP apps. Really need to make this
+        # better.
+        if "platform-" in service_name:
+            return "{0}:{1}".format(ip, port)
+        elif "cdap" in service_name:
+            redirectish_url = "http://{0}:{1}/application/{2}".format(ip, port,
+                    service_name)
+
+            r = requests.get(redirectish_url)
+            r.raise_for_status()
+            details = r.json()
+            # Pick out the details to expose to the component developers
+            return { key: details[key]
+                    for key in ["connectionurl", "serviceendpoints"] }
+        else:
+            return "{0}:{1}".format(ip, port)
+
+    try:
+        results = lookup_func(service_name)
+        return [ handle_result(result) for result in results ]
+    except Exception as e:
+        raise DiscoveryResolvingNameError(
+                "Failed to resolve name for {0}: {1}".format(service_name, e))
+
+def _resolve_configuration_dict(ch, service_name, config):
+    """
+    Helper used by both resolve_configuration_dict and get_configuration
+    """
+    if _has_connections(config):
+        rels = _get_relationships_from_consul(ch, service_name)
+        connection_types = _get_connection_types(config)
+        connection_names = _resolve_connection_types(service_name, connection_types, rels)
+        # NOTE: The hardcoded use of the first element. This is to keep things backwards
+        # compatible since resolve name now returns a list.
+        for key, conn in [(key, [_resolve_name(partial(_lookup_with_consul, ch), name)[0] for name in names]) for key, names in connection_names]:
+            config = util.update_json(config, key, conn)
+
+    _logger.info("Generated config: {0}".format(config))
+    return config
+
+#####
+# Public calls 
+#####
+
+def get_consul_hostname(consul_hostname_override=None):
+    """Get the Consul hostname"""
+    try:
+        return consul_hostname_override \
+                if consul_hostname_override else os.environ["CONSUL_HOST"]
+    except:
+        raise DiscoveryInitError("CONSUL_HOST variable has not been set!")
+
+def get_service_name():
+    """Get the full service name
+
+    This is expected to be given from whatever entity is starting this service
+    and given by an environment variable called "HOSTNAME"."""
+    try:
+        return os.environ["HOSTNAME"]
+    except:
+        raise DiscoveryInitError("HOSTNAME variable has not been set!")
+
+
+def resolve_name(consul_host, service_name, max_attempts=3):
+    """Resolve the service name
+
+    Do a service discovery lookup from Consul and return back the detailed connection
+    information.
+
+    Returns:
+    --------
+    For CDAP apps, returns a dict. All others a string with the format "<ip>:<port>"
+    """
+    ch = consul.Consul(host=consul_host)
+    lookup_func = partial(_lookup_with_consul, ch, max_attempts=max_attempts)
+    return _resolve_name(lookup_func, service_name)
+
+
+def resolve_configuration_dict(consul_host, service_name, config):
+    """
+    Utility method for taking a given service_name, and config dict, and resolving it
+    """
+    ch = consul.Consul(host=consul_host)
+    return _resolve_configuration_dict(ch, service_name, config)
+
+
+def get_configuration(override_consul_hostname=None, override_service_name=None,
+        from_cbs=True):
+    """Provides this service component's configuration information fully resolved
+
+    This method can either resolve the configuration locally here or make a
+    remote call to the config binding service. The default is to use the config
+    binding service.
+
+    Args:
+    -----
+    override_consul_hostname (string): Consul hostname to use rather than the one
+        set by the environment variable CONSUL_HOST
+    override_service_name (string): Use this name over the name set on the
+        HOSTNAME environment variable. Default is None.
+    from_cbs (boolean): True (default) means use the config binding service otherwise
+        set to False to have the config pulled and resolved by this library
+
+    Returns the fully resolved service component configuration as a dict
+    """
+    # Get config, bootstrap
+    consul_hostname = get_consul_hostname(override_consul_hostname)
+    # NOTE: We use the default port 8500
+    ch = consul.Consul(host=consul_hostname)
+    service_name = override_service_name if override_service_name else get_service_name()
+    _logger.info("service name: {0}".format(service_name))
+
+    if from_cbs:
+        return _get_configuration_resolved_from_cbs(ch, service_name)
+    else:
+        # The following will happen:
+        #
+        # 1. Fetching the configuration by service component name from Consul
+        # 2. Fetching the relationships for this service component by service component
+        # name
+        # 3. Pick out the connection types from the templetized fields in the configuration
+        # 4. Resolve the connection types with connection names using the step #2
+        # information
+        # 5. Resolve the connection names with the actual connection via queries to
+        # Consul using the connection name
+        config = _get_configuration_from_consul(ch, service_name)
+        return _resolve_configuration_dict(ch, service_name, config)
+
+
+def register_for_discovery(consul_host, service_ip, service_port):
+    """Register the service component for service discovery
+
+    This is required in order for other services to "discover" you so that you
+    can service their requests.
+
+    NOTE: Applications may not need to make this call depending upon if the
+    environment is using Registrator.
+    """
+    ch = consul.Consul(host=consul_host)
+    service_name = get_service_name()
+
+    if _register_with_consul(ch, service_name, service_ip, service_port, "health"):
+        _logger.info("Registered to consul: {0}".format(service_name))
+    else:
+        _logger.error("Failed to register to consul: {0}".format(service_name))
+        raise DiscoveryRegistrationError()
diff --git a/python-discovery-client/discovery_client/util.py b/python-discovery-client/discovery_client/util.py
new file mode 100644
index 0000000..b59647a
--- /dev/null
+++ b/python-discovery-client/discovery_client/util.py
@@ -0,0 +1,78 @@
+# 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.
+
+import collections
+import logging, sys
+import six
+
+#####
+# Module contains utility methods
+#####
+
+def update_json(src, key, value):
+    """Updates a nested JSON value
+
+    This method does a recursive lookup for a value given a compound key and then
+    replaces that value with the passed in new value.
+
+    For example, given a src json { "a": [ { "aa": 1 }, "foo" ], "b": "2 } and a
+    key ("a", 0, "aa"), the value parameter would replace 1.
+
+    :param src: json to update
+    :type src: dict or list
+    :param key: compound key used to lookup
+    :type key: tuple
+    :param value: new value used to replace
+    :type value: object
+
+    :return: updated json
+    """
+    if key:
+        src[key[0]] = update_json(src[key[0]], key[1:], value)
+    else:
+        # We've found the value we want to replace regardless of whether or not
+        # the object we are replacing is another copmlicated data structure.
+        src = value
+    return src
+
+def _has_handlers(logger):
+    """Check if logger has handlers"""
+    if six.PY3:
+        return logger.hasHandlers()
+    else:
+        # TODO: Not sure how to check if a handler has already been attached
+        # WATCH: Downside is lines get printed multiple times
+        return False
+
+def get_logger(name, level=logging.INFO):
+    """Get a logger with sensible defaults
+
+    This method returns a logger from logging by name that has been set with sensible
+    defaults if the logger hasn't already been setup with any handlers. The
+    default handler is a stream handler to stdout.
+    """
+    logger = logging.getLogger(name)
+
+    if not _has_handlers(logger):
+        # No handlers attached which means logging hasn't been setup. Set
+        # "sensible" defaults which means stdout, INFO
+        logger.setLevel(level)
+        logger.addHandler(logging.StreamHandler(stream=sys.stdout))
+
+    return logger