service-framework 0.0.19

A package for re-defining microservice architecture

Service Framework

Note This library is currently in alpha. While I use it for a few private repos this library can be changes at any moment.

Installing

As a Library

pip install service_framework

For Debugging

To install locally for testing run the following command from the base directory.

pip install -e .

Running

From Command Line

Run the following from the directory the Service Framework was locally built. As this directory houses the packaged Service Framework as a python "Egg" file.

python -m service_framework

# OR

service_framework

Useful Command Line Arguments

Below are a few useful arguments...

# Used for Service Setup
-a  Addresses Path (Relative)
-c  Config Path
-m  Main Mode Flag
-s  Service Path (Relative)
-wt Min Wait Time between each service loop

# Used for Logging
-cl Console Log Level
-f  File Log Level
-bc Backup Count (Number of hourly log files to keep)
-l  Log Path (Relative)

As An Object

To allow multiple services to be run in sync and programmatically created or destroyed it has been neatly packaged into a class for use. The Service Class should mirror the same requirements as running the framework from the command line. Quite frankly, because running it from the command line just uses this class underneath. Below are the commands on how to use this class:

# Useage Example

from importlib import import_module
from service_framework import Service

service_relative_path = './path_to_service_file/service_specification.py'
service_module = import_module('package.path.to.module')
config = {'some_config_key': 'some_config_value'}
addresses = {'look below this can get complicated'}

my_service = Service(service_path=service_relative_path, config=config, addresses=addresses)
also_my_service = Service(service_module=service_module, config=config, addresses=addresses)


# To run the service as a "main service" or in "main mode" in the background.
my_service.run_service_as_main()

# To run the service regularly and in the background/non-blocking.
my_service.run_service()

# To stop the service's execution.
my_service.stop_service()

# To run the service in it's respective mode and block (stop execution past this line):
my_service.run_service_as_main_blocking()
my_service.run_service_blocking()

Useful Optional Arguments

Here are some other, optional parameters, that can be passed into the Service object:

console_loglevel='INFO'
log_path=None
file_loglevel='INFO'
backup_count=24
service_loop_min_wait_time=0

These Parameters are the same as their command line counterparts.

Logging

To log inside of your service file import the logger that's pre-created.

from service_framework import get_logger

LOG = get_logger()

Addresses Path

If the addresses path is provided, the addresses JSON file will be loaded into the service framework. This allows the framework to setup each connection of the services connections. Example:

# Command
-a "./addresses.json"

# Addresses.json
{
  "in": {
    "connection_name": {
      "socket_name": "127.0.0.1:8001",
      "socket_name_2: "127.0.0.1:8002"
    },
    "connection_name_2": {
      "socket_name": "256.128.65.1:9000"
    },
  },
  "out": {}
}

Config Path

This is the relative path to the config json file that will be passed into the service. This file is not required but is useful if one wants to pass configuration information into a service. Example:

# Command:
-c "./config.json"

# Example Config.json:
{
  "required": {
    "config_property_1": 12345,
    "config_property_2": ["list_item_1", "list_item_2", "list_item_3"],
    "config_property_3": {
      "key_1": "value_1",
      "key_2": "value_2"
    }
  },
  "optional": {
    "config_property_4": "TestTestTest"
  }
}

Main Mode Flag

This flag is used to start the service in "main_mode". This mode DOES NOT allow the use of inbound connections at all. It simply runs the provided main function in the service and all the connections corresponding with the provided models. The main function must have a predefined signature seen below.

# Example main function
def main(to_send, config):

Service Path

This is the relative path to the service python file that will be used for starting and running the service.

# Command
-s "./service.json"

Custom Environmental Arguments

Any additional arguments that are passed will automatically be added to the config. See below for an example...

# Calling the below
python -m service_framework -s ./service.py --random_variable HELLO

# Will cause a config similar to below
config = {
    'random_variable': 'HELLO',
}

Help Command

Use the below command to get a helpful output for the service framework.

python -m service_framework -h

Building Blocks

An abstract overview of the building blocks.

Connections

Connections are the glue that holds services together. Any communication between services should be done via connections.

Leading Edge Services

These are services that use the "main mode". If all services are plotted as a graph where they are connected by connections these services have no inbound connections from other services.

Services

A service is a block of code that does one thing and one thing well. The goal of this framework is to make spinning up and dealing with a large number of services easily.

Implementation

Leading Edge Services

Required Methods

• Main Method
  • Only Method called in this service
  • ex. main(to_send, config)

Optional Methods

• Setup Config
  • ex. setup_config(config)
  • This method is called before the main method.
  • This method is used to update the config before it's used.
  • This method merges the responses with the provided config. (Overwrites keys)
  • ex.

return {
    'required': {
        'argument_1': 'first_argument',
    },
    'optional': {
        'argument_2': 'the_second_argument',
    },
}

• Setup Connections
  • ex. setup_connections(config)
  • This method is called at the start of the service
  • This method must return all arguments for the given connection name.
  • ex.

return {
  'connection_name_1': {
    'argument_1': 'value',
    'argument_2': 123, 
  },
  'connection_name_2': {
    'argument_1': 'test_test',
  },
}

• Sigint Handler
  • ex. sigint_handler(sigint, frame, to_send, config)
  • This method is called whenever a sigint is provided.
• Sigterm Handler
  • ex. sigterm_handler(signum, frame, to_send, config)
  • This method is called whenever a sigterm is provided.

Optional Models

Each Model is only required if it's used in the leading edge service.

• config_model
• connection_models

Services

Required Methods

• Method for each "in" Connection Model
  • This method is called whenever a message from this connection is received
  • The mapping between function and model is located in the model
  • ex. function_name_in_conn_model(args, to_send, config)

Optional Methods

• Setup Connections Method
  • ex. setup_connections(config)
  • This method is only required if a connection has required arguments
  • This method is called at the start of the service
  • This method must return all arguments for the given connection name.
  • ex.

return {
  'connection_name_1': {
    'argument_1': 'value',
    'argument_2': 123, 
  },
  'connection_name_2': {
    'argument_1': 'test_test',
  },
}

• Sigint Handler

  • ex. sigint_handler(sigint, frame, to_send, config)
  • This method is called whenever a sigint is provided.

• Sigterm Handler

  • ex. sigterm_handler(sigint, frame, to_send, config)
  • This method is called whenever a sigterm is provided.

• Init Function

  • ex. init_function(to_send, config)
  • This method is called before the main method or service framework.

Optional Models

Models are only needed if used in the service.

• config_model
• connection_models

Parameters Passed

"args"::dict

When this function is called these are the "arguments" passed. These arguments are pulled from the in connector that is associated with this function.

"to_send"::function

def to_send(connection_name, args):
    """
    connection_name::str The name of the connection defined in the corresponding model.
    args::{'str': value} This is a dict of the args to be passed to the connection.
    """

This function takes the provided args and sends them to the desired connection.

"config"::dict

This is a dictionary that is a culmination of config file data and environment variables.

Model Layout

Config Model

Overview

It's a key value store of config information that is passed into the model.

Example

config_model = {
    'required': {       # Optional
        'symbol': str,
    },
    'optional': {},     # Optional
}

Connection Models

Overview

Triggers work/functions between different services.

Example

connection_models = {
    'in': {
        'cancel_order': {
            'connection_type': 'replyer',                  # Required
            'required_creation_arguments': {               # Optional
                'on_new_cancel_order: on_new_cancel_order, # Optional
            },
            'optional_creation_arguments': {},             # Optional
            'required_connection_arguments': {},           # Depends on the Connection
            'optional_connection_arguments': {},           # Depends on the Connection
            'required_arguments': {                        # Optional
                'order_id': str,
            },
            'optional_arguments': {},                      # Optional
            'required_return_arguments': {                 # Optional
                'order_id': str,
            },
            'optional_return_arguments': {},               # Optional
        }
    },
    'out': {
        'cancel_order_on_coinbase': {
            'connection_type': 'external_target',     # Required
            'required_creation_arguments': {          # Optional
                'target': 'CbproClient.cancel_order', 
            },
            'optional_creation_arguments': {}         # Optional
            'required_connection_arguments': {},      # Depends on the Connection
            'optional_connection_arguments': {},      # Depends on the Connection
            'required_arguments': {                   # Optional
                'order_id': str,
            },
            'optional_arguments': {},                 # Optional
            'required_return_arguments': None,        # Optional
            'optional_return_arguments': None,        # Optional
        },
    },
}

Connection Types

In

Replyer

Used to wrap a ZMQ "Replyer" socket. Triggers a provided method on new requester message. Link to Replyer File

Subscriber

Used to wrap a ZMQ "Subscriber" socket. Triggers a provided method on a new published message. Also has XSUB support. Link to Subscriber File

Out

External Target

Used to wrap an external call and make sure all of the arguments are properly formatted and returned. Can use to_send('connection', 'external_target_name', {'args': 'here'} to send a payload to the external service.

Publisher

Used to wrap a ZMQ "Publisher" socket. Can use to_send('connection', 'publisher_conn_name', {'args': 'here'} to send a payload to the connected subscribers. Also has XPUB support. Link to Publisher File

Requester

Used to wrap a ZMQ "Requester" socket. Can use to_send('connection', 'requester_conn_name', {'args': 'here'} to send a payload to the connected replyer. Link to Requester File

Field and Argument Examples

Dictionary

# Abstract Model Representation
'dictionary_argument': {Type: Type},

# Actually Passed
'dictionary_argument': {Decimal: Decimal},

Service Framework Running Workflow

• Load Service File to get models
• Config:
  • Get config file location
  • Get additional environmental variables
  • Run setup_config function
  • Check config parameters
• Addresses:
  • Load addresses config
  • Run setup_addresses if available
• Connections:
  • Load Connections Config
  • Run setup_connections function
  • Get connections (in and out)
• Sig Handlers:
  • Sets up Sigint and sigterm handling if needed
  • Runs sigint_handler and sigterm_handler
• Init Function:
  • Run init_function before running main or service loop
• Runs either main or service loop
• Honestly, check the entrance_point method