Initial release of context service

manifests/contextservice.yaml

+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: contextservice
+spec:
+  selector:
+    matchLabels:
+      app: contextservice
+  template:
+    metadata:
+      labels:
+        app: contextservice
+    spec:
+      terminationGracePeriodSeconds: 5
+      containers:
+      - name: server
+        image: context_service:develop
+        imagePullPolicy: Never
+        ports:
+        - containerPort: 7070
+        env:
+        - name: DB_ENGINE
+          value: "redis"
+        - name: REDISDB_DATABASE_ID
+          value: "0"
+        - name: LOG_LEVEL
+          value: "DEBUG"
+        readinessProbe:
+          exec:
+            command: ["/bin/grpc_health_probe", "-addr=:7070"]
+        livenessProbe:
+          exec:
+            command: ["/bin/grpc_health_probe", "-addr=:7070"]
+        resources:
+          requests:
+            cpu: 250m
+            memory: 512Mi
+          limits:
+            cpu: 700m
+            memory: 1024Mi
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: contextservice
+spec:
+  type: ClusterIP
+  selector:
+    app: contextservice
+  ports:
+  - name: grpc
+    port: 7070
+    targetPort: 7070

manifests/redisdb.yaml

+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: redisdb
+spec:
+  selector:
+    matchLabels:
+      app: redisdb
+  replicas: 1
+  template:
+    metadata:
+      labels:
+        app: redisdb
+        version: v1
+    spec:
+      containers:
+      - name: redisdb
+        image: redis:6.2
+        ports:
+        - containerPort: 6379
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: redisdb
+  labels:
+    app: redisdb
+spec:
+  type: ClusterIP
+  selector:
+    app: redisdb
+  ports:
+  - name: redisdb
+    protocol: TCP
+    port: 6379
+    targetPort: 6379
+---

src/build.sh

 #!/usr/bin/env bash
 
-cd monitoring
-./genproto.sh
-cd ..
+# Make folder containing the script the root folder for its execution
+cd $(dirname $0)
+
+echo "BUILD context"
+context/genproto.sh
+docker build -t "context_service:develop" -f context/Dockerfile_develop --quiet .
+docker build -t "context_service:test" -f context/Dockerfile_test --quiet .
 
 echo "BUILD monitoring"
-docker build -t "monitoring:dockerfile" -f monitoring/Dockerfile .
+monitoring/genproto.sh
+docker build -t "monitoring_service:develop" -f monitoring/Dockerfile --quiet .
 
+echo "Prune unused images"
+docker image prune --force

src/common/tools/RetryDecorator.py

+# This decorator re-executes the decorated function when it raises an exception. It enables to control the exception
+# classes that should trigger the re-execution, the maximum number of retries, the delay between retries, and set the
+# execution of a preparation method before every retry. The delay is specfied by means of user-customizable functions.
+#
+# Delay functions should return a compute function with a single parameter, the number of retry. For instance:
+#   delay_linear(initial=0, increment=0):
+#       adds a constant delay of 0 seconds between retries
+#   delay_linear(initial=1, increment=0):
+#       adds a constant delay of 1 second between retries
+#   delay_linear(initial=1, increment=0.5, maximum=10):
+#       adds an increasing delay between retries, starting with 1 second, and incresing it linearly by steps of 0.5
+#       seconds, up to 10 seconds, every time an exception is caught within the current execution.
+#       E.g. 1.0, 1.5, 2.0, 2.5, ..., 10.0, 10.0, 10.0, ...
+#   delay_exponential(initial=1, increment=1): adds a constant delay of 1 second between retries
+#   delay_exponential(initial=1, increment=2, maximum=10):
+#       adds an increasing delay between retries, starting with 1 second, and incresing it exponentially by steps of 2
+#       seconds, up to 10 seconds,  every time an exception is caught within the current execution.
+#       E.g. 1.0, 2.0, 4.0, 8.0, 10.0, 10.0, 10.0, ...
+
+# Arguments:
+# - exceptions: defines the set of exception classes to be catched for reconnection. Others are re-raised.
+#   By default all exceptions are re-raised.
+# - max_retries: defines the maximum number of retries acceptable before giving up. By default, 0 retries are executed.
+# - delay_function: defines the delay computation method to be used. By default, delay_linear with a fixed delay of 0.1
+#   seconds is used.
+# - prepare_method_name: if not None, defines the name of the preparation method within the same class to be executed
+#   when an exception in exceptions is caught, and before running the next retry. By default, is None, meaning that no
+#   method is executed.
+# - prepare_method_args: defines the list of positional arguments to be provided to the preparation method. If no
+#   preparation method is specified, the argument is silently ignored. By default, an empty list is defined.
+# - prepare_method_kwargs: defines the dictionary of keyword arguments to be provided to the preparation method. If no
+#   preparation method is specified, the argument is silently ignored. By default, an empty dictionary is defined.
+
+import time
+
+def delay_linear(initial=0, increment=0, maximum=None):
+    def compute(num_try):
+        delay = initial + (num_try - 1) * increment
+        if maximum is not None: delay = max(delay, maximum)
+        return delay
+    return compute
+
+def delay_exponential(initial=1, increment=1, maximum=None):
+    def compute(num_try):
+        delay = initial * (num_try - 1) ^ increment
+        if maximum is not None: delay = max(delay, maximum)
+        return delay
+    return compute
+
+def retry(exceptions=set(), max_retries=0, delay_function=delay_linear(initial=0, increment=0),
+          prepare_method_name=None, prepare_method_args=[], prepare_method_kwargs={}):
+    def _reconnect(func):
+        def wrapper(self, *args, **kwargs):
+            if prepare_method_name is not None:
+                prepare_method = getattr(self, prepare_method_name, None)
+                if prepare_method is None: raise Exception('Prepare Method ({}) not found'.format(prepare_method_name))
+            num_try, given_up = 0, False
+            while not given_up:
+                try:
+                    return func(self, *args, **kwargs)
+                except Exception as e:
+                    if not isinstance(e, tuple(exceptions)): raise
+
+                    num_try += 1
+                    given_up = num_try > max_retries
+                    if given_up: raise Exception('Giving up... {} tries failed'.format(max_retries))
+                    if delay_function is not None: time.sleep(delay_function(num_try))
+
+                    if prepare_method_name is not None: prepare_method(*prepare_method_args, **prepare_method_kwargs)
+        return(wrapper)
+    return(_reconnect)

src/context/Config.py

+import logging
+
+# gRPC settings
+SERVICE_PORT = 7070
+MAX_WORKERS  = 10
+GRACE_PERIOD = 60
+LOG_LEVEL    = logging.WARNING
+
+# Prometheus settings
+METRICS_PORT = 8080

src/context/Dockerfile_develop

+FROM python:3-slim
+
+# Install dependencies
+RUN apt-get --yes --quiet --quiet update && \
+    apt-get --yes --quiet --quiet install wget g++ && \
+    rm -rf /var/lib/apt/lists/*
+
+# Set Python to show logs as they occur
+ENV PYTHONUNBUFFERED=0
+
+# Download the gRPC health probe
+RUN GRPC_HEALTH_PROBE_VERSION=v0.2.0 && \
+    wget -qO/bin/grpc_health_probe https://github.com/grpc-ecosystem/grpc-health-probe/releases/download/${GRPC_HEALTH_PROBE_VERSION}/grpc_health_probe-linux-amd64 && \
+    chmod +x /bin/grpc_health_probe
+
+# Get generic Python packages
+RUN python3 -m pip install --upgrade pip setuptools wheel pip-tools
+
+# Set working directory
+WORKDIR /var/teraflow
+
+# Create module sub-folders
+RUN mkdir -p /var/teraflow/context
+
+# Get Python packages per module
+COPY context/requirements.in context/requirements.in
+RUN pip-compile --output-file=context/requirements.txt context/requirements.in
+RUN python3 -m pip install -r context/requirements.in
+
+# Add files into working directory
+COPY common/. common
+COPY context/. context
+
+# Start context service
+ENTRYPOINT ["python", "-m", "context.service"]

src/context/Dockerfile_test

+FROM context_service:develop
+
+# Run integration tests
+ENTRYPOINT ["pytest", "-v", "--log-level=DEBUG", "context/tests/test_integration.py"]

src/context/client/ContextClient.py

+import grpc, logging
+from google.protobuf.json_format import MessageToDict
+from common.tools.RetryDecorator import retry, delay_exponential
+from context.proto.context_pb2_grpc import ContextServiceStub
+
+LOGGER = logging.getLogger(__name__)
+MAX_RETRIES = 15
+DELAY_FUNCTION = delay_exponential(initial=0.01, increment=2.0, maximum=5.0)
+
+class ContextClient:
+    def __init__(self, address, port):
+        self.endpoint = '{}:{}'.format(address, port)
+        LOGGER.debug('Creating channel to {}...'.format(self.endpoint))
+        self.channel = None
+        self.stub = None
+        self.connect()
+        LOGGER.debug('Channel created')
+
+    def connect(self):
+        self.channel = grpc.insecure_channel(self.endpoint)
+        self.stub = ContextServiceStub(self.channel)
+
+    def close(self):
+        if(self.channel is not None): self.channel.close()
+        self.channel = None
+        self.stub = None
+
+    @retry(exceptions=set(), max_retries=MAX_RETRIES, delay_function=DELAY_FUNCTION, prepare_method_name='connect')
+    def GetTopology(self, request):
+        LOGGER.debug('GetTopology request: {}'.format(request))
+        response = self.stub.GetTopology(request)
+        LOGGER.debug('GetTopology result: {}'.format(response))
+        return MessageToDict(
+            response, including_default_value_fields=True, preserving_proto_field_name=True,
+            use_integers_for_enums=False)

src/context/data/topo_nsfnet.json

+{
+    "topoId": {
+        "contextId": {"contextUuid": {"uuid": "default"}},
+        "topoId": {"uuid": "topo0-nsfnet"}
+    },
+    "device" : [
+        {"device_id": {"device_id": {"uuid": "1" }}, "device_type": "ROADM", "device_config": {"device_config": ""}, "devOperationalStatus": 1, "endpointList" : [
+            {"port_id": {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "1" }}, "port_id": {"uuid" : "101"}}, "port_type": "LINE"}
+        ]},
+        {"device_id": {"device_id": {"uuid": "2" }}, "device_type": "ROADM", "device_config": {"device_config": ""}, "devOperationalStatus": 1, "endpointList" : [
+            {"port_id": {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "2" }}, "port_id": {"uuid" : "201"}}, "port_type": "LINE"}
+        ]},
+        {"device_id": {"device_id": {"uuid": "3" }}, "device_type": "ROADM", "device_config": {"device_config": ""}, "devOperationalStatus": 1, "endpointList" : [
+            {"port_id": {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "3" }}, "port_id": {"uuid" : "301"}}, "port_type": "LINE"}
+        ]},
+        {"device_id": {"device_id": {"uuid": "4" }}, "device_type": "ROADM", "device_config": {"device_config": ""}, "devOperationalStatus": 1, "endpointList" : [
+            {"port_id": {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "4" }}, "port_id": {"uuid" : "401"}}, "port_type": "LINE"}
+        ]},
+        {"device_id": {"device_id": {"uuid": "5" }}, "device_type": "ROADM", "device_config": {"device_config": ""}, "devOperationalStatus": 1, "endpointList" : [
+            {"port_id": {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "5" }}, "port_id": {"uuid" : "501"}}, "port_type": "LINE"}
+        ]},
+        {"device_id": {"device_id": {"uuid": "6" }}, "device_type": "ROADM", "device_config": {"device_config": ""}, "devOperationalStatus": 1, "endpointList" : [
+            {"port_id": {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "6" }}, "port_id": {"uuid" : "601"}}, "port_type": "LINE"}
+        ]},
+        {"device_id": {"device_id": {"uuid": "7" }}, "device_type": "ROADM", "device_config": {"device_config": ""}, "devOperationalStatus": 1, "endpointList" : [
+            {"port_id": {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "7" }}, "port_id": {"uuid" : "701"}}, "port_type": "LINE"}
+        ]},
+        {"device_id": {"device_id": {"uuid": "8" }}, "device_type": "ROADM", "device_config": {"device_config": ""}, "devOperationalStatus": 1, "endpointList" : [
+            {"port_id": {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "8" }}, "port_id": {"uuid" : "801"}}, "port_type": "LINE"}
+        ]},
+        {"device_id": {"device_id": {"uuid": "9" }}, "device_type": "ROADM", "device_config": {"device_config": ""}, "devOperationalStatus": 1, "endpointList" : [
+            {"port_id": {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "9" }}, "port_id": {"uuid" : "901"}}, "port_type": "LINE"}
+        ]},
+        {"device_id": {"device_id": {"uuid": "10"}}, "device_type": "ROADM", "device_config": {"device_config": ""}, "devOperationalStatus": 1, "endpointList" : [
+            {"port_id": {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "10"}}, "port_id": {"uuid" : "1001"}}, "port_type": "LINE"}
+        ]},
+        {"device_id": {"device_id": {"uuid": "11"}}, "device_type": "ROADM", "device_config": {"device_config": ""}, "devOperationalStatus": 1, "endpointList" : [
+            {"port_id": {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "11"}}, "port_id": {"uuid" : "1101"}}, "port_type": "LINE"}
+        ]},
+        {"device_id": {"device_id": {"uuid": "12"}}, "device_type": "ROADM", "device_config": {"device_config": ""}, "devOperationalStatus": 1, "endpointList" : [
+            {"port_id": {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "12"}}, "port_id": {"uuid" : "1201"}}, "port_type": "LINE"}
+        ]},
+        {"device_id": {"device_id": {"uuid": "13"}}, "device_type": "ROADM", "device_config": {"device_config": ""}, "devOperationalStatus": 1, "endpointList" : [
+            {"port_id": {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "13"}}, "port_id": {"uuid" : "1301"}}, "port_type": "LINE"}
+        ]},
+        {"device_id": {"device_id": {"uuid": "14"}}, "device_type": "ROADM", "device_config": {"device_config": ""}, "devOperationalStatus": 1, "endpointList" : [
+            {"port_id": {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "14"}}, "port_id": {"uuid" : "1401"}}, "port_type": "LINE"}
+        ]} 
+    ],
+    "link" : [
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "1" }}, "port_id": {"uuid": "101" }},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "2" }}, "port_id": {"uuid": "201" }}
+        ]},
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "1" }}, "port_id": {"uuid": "101" }},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "3" }}, "port_id": {"uuid": "301" }}
+        ]},
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "1" }}, "port_id": {"uuid": "101" }},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "8" }}, "port_id": {"uuid": "801" }}
+        ]},
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "2" }}, "port_id": {"uuid": "201" }},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "3" }}, "port_id": {"uuid": "301" }}
+        ]},
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "2" }}, "port_id": {"uuid": "201" }},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "4" }}, "port_id": {"uuid": "401" }}
+        ]},
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "3" }}, "port_id": {"uuid": "301" }},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "6" }}, "port_id": {"uuid": "601" }}
+        ]},
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "4" }}, "port_id": {"uuid": "401" }},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "5" }}, "port_id": {"uuid": "501" }}
+        ]},
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "4" }}, "port_id": {"uuid": "401" }},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "11"}}, "port_id": {"uuid": "1101"}}
+        ]},
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "5" }}, "port_id": {"uuid": "501" }},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "6" }}, "port_id": {"uuid": "601" }}
+        ]},         
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "5" }}, "port_id": {"uuid": "501" }},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "7" }}, "port_id": {"uuid": "701" }}
+        ]},                                                          
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "6" }}, "port_id": {"uuid": "601" }},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "10"}}, "port_id": {"uuid": "1001"}}
+        ]},                                                  
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "6" }}, "port_id": {"uuid": "601" }},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "13"}}, "port_id": {"uuid": "1301"}}
+        ]},                                                  
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "7" }}, "port_id": {"uuid": "701" }},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "8" }}, "port_id": {"uuid": "801" }}
+        ]},                                                  
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "8" }}, "port_id": {"uuid": "801" }},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "9" }}, "port_id": {"uuid": "901" }}
+        ]},                                                  
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "9" }}, "port_id": {"uuid": "901" }},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "10"}}, "port_id": {"uuid": "1001"}}
+        ]}, 
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "9" }}, "port_id": {"uuid": "901" }},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "12"}}, "port_id": {"uuid": "1201"}}
+        ]},   
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "9" }}, "port_id": {"uuid": "901" }},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "14"}}, "port_id": {"uuid": "1401"}}
+        ]},
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "11"}}, "port_id": {"uuid": "1101"}},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "12"}}, "port_id": {"uuid": "1201"}}
+        ]},   
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "11"}}, "port_id": {"uuid": "1101"}},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "14"}}, "port_id": {"uuid": "1401"}}
+        ]},     
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "12"}}, "port_id": {"uuid": "1201"}},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "13"}}, "port_id": {"uuid": "1301"}}
+        ]},
+        {"endpointList" : [
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "13"}}, "port_id": {"uuid": "1301"}},
+            {"topoId": {"topoId": {"uuid": "topo0-nsfnet"}}, "dev_id": {"device_id": {"uuid": "14"}}, "port_id": {"uuid": "1401"}}
+        ]}      
+    ]
+}

src/context/database/Factory.py

+import logging, os
+from enum import Enum
+from .inmemory.InMemoryDatabase import InMemoryDatabase
+from .redis.RedisDatabase import RedisDatabase
+
+LOGGER = logging.getLogger(__name__)
+
+class DatabaseEngineEnum(Enum):
+    INMEMORY = 'inmemory'
+    REDIS = 'redis'
+    #MONGO = 'mongo'
+    #RETHINK = 'rethink'
+    #ETCD = 'etcd'
+
+ENGINES = {
+    DatabaseEngineEnum.INMEMORY.value: InMemoryDatabase,
+    DatabaseEngineEnum.REDIS.value: RedisDatabase,
+    #DatabaseEngineEnum.MONGO.value: MongoDatabase,
+    #DatabaseEngineEnum.RETHINK.value: RethinkDatabase,
+    #DatabaseEngineEnum.ETCD.value: EtcdDatabase,
+}
+
+DEFAULT_DB_ENGINE = DatabaseEngineEnum.INMEMORY
+
+def get_database(engine=None, **parameters):
+    if engine is None: engine = os.environ.get('DB_ENGINE', DEFAULT_DB_ENGINE)
+    if(isinstance(engine, DatabaseEngineEnum)): engine = engine.value
+    LOGGER.info('Selected Database Engine: {}'.format(engine))
+    engine_class = ENGINES.get(engine)
+    if engine_class is None: raise Exception('Unsupported Engine({})'.format(engine))
+    return engine_class(**parameters)

src/context/database/inmemory/InMemoryDatabase.py

+import logging, json
+
+LOGGER = logging.getLogger(__name__)
+FILEPATH = 'context/data/topo_nsfnet.json'
+
+class InMemoryDatabase:
+    def __init__(self, filepath=FILEPATH, **parameters):
+        with open(filepath, 'r') as f:
+            self.json_topology = json.loads(f.read())
+
+    def get_topology(self):
+        return(self.json_topology)

src/context/database/redis/RedisDatabase.py

+import logging, json, os, redis
+#from .context_api.Context import Context
+
+LOGGER = logging.getLogger(__name__)
+
+# 60.0 seconds (aprox) in incremental steps from 0.002 till 29.99 seconds
+RETRY_DELAY_INITIAL = 0.002
+RETRY_DELAY_INCREMENT = 1.831
+MAX_RETRIES = 15
+
+URL_TEMPLATE = 'redis://{host}:{port}/{dbid}'
+
+class RedisDatabase:
+    def __init__(self, **parameters):
+        host = os.environ.get('REDISDB_SERVICE_HOST')
+        if(host is None): raise Exception('EnvironmentVariable(REDISDB_SERVICE_HOST) not found')
+        port = os.environ.get('REDISDB_SERVICE_PORT')
+        if(port is None): raise Exception('EnvironmentVariable(REDISDB_SERVICE_PORT) not found')
+        dbid = os.environ.get('REDISDB_DATABASE_ID')
+        if(dbid is None): raise Exception('EnvironmentVariable(REDISDB_DATABASE_ID) not found')
+        self.redis_url = URL_TEMPLATE.format(host=host, port=port, dbid=dbid)
+        self.handler = None
+        self.connect() # initialize self.handler and connect to server
+
+    def connect(self):
+        self.handler = redis.Redis.from_url(self.redis_url)
+
+    def close(self):
+        if(self.handler is not None): del self.handler
+        self.handler = None
+
+    def get_topology(self):
+        str_topology = self.handler.get('topology')
+        if(str_topology is None):
+            with open('context/data/topo_nsfnet.json', 'r') as f:
+                json_topology = json.loads(f.read())
+            str_topology = json.dumps(json_topology)
+            self.handler.setnx('topology', str_topology)
+            json_topology['source'] = 'redis missing, loaded from file'
+        else:
+            json_topology = json.loads(str_topology)
+            json_topology['source'] = 'redis found!'
+        return(json_topology)
+
+    #def __getattr__(self, method_name):
+    #    # Expose all methods in the database engine as owned
+    #    def method(*args, **kwargs):
+    #        num_try, delay = 1, RETRY_DELAY_INITIAL
+    #        while num_try <= MAX_RETRIES:
+    #            try:
+    #                handler_method = getattr(self.handler, method_name, None)
+    #                if handler_method is None: raise Exception('Redis does not support method({})'.format(method_name))
+    #                return handler_method(*args, **kwargs)
+    #            except ConnectionError: # as e:
+    #                #if('Channel is closed' not in str(e)): raise
+    #                self.connect() # Try to reconnect
+    #                time.sleep(delay)
+    #                num_try, delay = num_try + 1, delay * RETRY_DELAY_INCREMENT
+    #        raise Exception('Unable to reconnect to Redis after {}'.format(MAX_RETRIES))
+    #    return(method)

src/context/genproto.sh

+#!/bin/bash -eu
+#
+# Copyright 2018 Google LLC
+#
+# 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.
+
+#!/bin/bash -e
+
+# Make folder containing the script the root folder for its execution
+cd $(dirname $0)
+
+rm -rf proto/*.py
+touch proto/__init__.py
+
+python -m grpc_tools.protoc -I../../proto --python_out=proto --grpc_python_out=proto context.proto
+
+sed -i -E 's/(import\ .*)_pb2/from context.proto \1_pb2/g' proto/context_pb2.py
+sed -i -E 's/(import\ .*)_pb2/from context.proto \1_pb2/g' proto/context_pb2_grpc.py