DiscoveRed

Python service discovery using Redis

Why?

Because there's no real lightweight service discovery mechanisms for Python that I could find, so I wrote my own.

How does it work?

DiscoveRed uses Redis as a k/v store to hold service information

The TTL feature

Unlike most service discovery methods, DiscoveRed doesn't require clients to re-register every n-seconds. This functionality can be enabled, though, through the use of the ttl option when instantiating the class. By setting the ttl to a positive integer, the keys that hold node information can be deprecated after n-seconds. This is useful if you are doing any kind of load balancing or monitoring off of the discovery information, or if you just want to replicate classic behavior.

The AUTO feature

If you're anything like me you enjoy having more information than you probably need at any given time. I've implemented a feature that uses psutil and the platform library to auto-discover information about nodes as they register. This feature is automatically enabled, but can be overridden by the auto flag when instantiating the ServiceDiscovery class, or by overriding the auto parameter on calls to register_node() and setting node=False. This is useful in conjunction with the TTL feature to avoid unnecessary probing (and therefore call time) when making subsequent "check in" node registrations.

API

discovered.ServiceDiscovery(redis_host, redis_port, redis_db, redis_auth, ttl, service_group, auto)

    redis_host (default: localhost) : redis host to connect to
    redis_port (default: 6379) : redis port
    redis_db (default: 0) : redis db index for the service discovery information
    redis_auth (default: None) : redis auth string if required
    ttl (default: -1) : set a TTL (seconds) on nodes, requiring them to re-register to stay enabled
    service_group (default: default) : logical partition name for service discovery
    auto (default: True) : auto-discover node details on registration

    Instantiates a new connection to the Redis service discovery keys.

    Returns: None


    register_service(service_name, endpoint, [endpoint_type, auth_type, auth_credentials, backend, description])

        service_name : the service name for the new service
        endpoint : the endpoint of whatever service this service is offering
        endpoint_type (default: '') : descriptive type for endpoint
        auth_type (default: None) : type of auth required for endpoint
        auth_credentials (default: None) : credentials for the endpoint
        backend (default: '') : descriptive label for the backend service
        description (default: '') : human-readable description of the service

        Registers a new service with discovery.

        Returns: dict


    register_node(service_name, node_name, [ ip, fqdn, os, platform_name, arch, cpu_count, memory, last_boot, auto])

        service_name : the service the node belongs to
        node_name : friendly name for the node; must be unique
        ip (default: None) : IP address of the node
        fqdn (default: None) : the FQDN of the node
        os (default: None) : the operating system of the node
        platform_name (default: None) : the OS type of the system (Windows, Linux, Darwin, etc.)
        arch (default: None) : system architecture of the node (ex. x86_64, i386, etc.)
        cpu_count (default: None) : number of cores for the node
        memory (default: None) : amount of available virtual memory, in MB
        last_boot (default: None) : timestamp of the node's last restart
        auto (default: True) : auto-discover node info, can override __init__'s auto setting

        Registers a new node and associates it with a service

        Returns: dict


    get_service(service_name)

        service_name : name of the service info to get

        Gets information about a service

        Returns: dict


    get_nodes(service_name)

        service_name : the service to get the node information about

        Gets information about registered nodes for a service

        Returns: list


    list_services()

        Lists all services in the configured service group

        Returns: list


    list_service_groups()

        Lists all service groups on the Redis host

        Returns: list


    remove_node(service_name, node_name)

        service_name : name of the service the node belongs to
        node_name : the friendly name of the node to remove

        Removes a node from a service

        Returns: str


    remove_service(service_name)

        service_name : name of the service to remove

        Removes a service from the service group

        Returns: str


    remove_service_group(service_group)

        service_group : name of the service group to remove

        Removes an entire service group from the service discovery.

        Returns: str

TODO

• Redis Sentinel integration
• Submit to PyPi