clusterduck

A better way to supervise your clusters and services.

The project is recently hatched and in the stage of active development.

Clusterduck is a robust solution for real-time distributed monitoring and self-healing clustering.

• Raft consensus algorithm. Ducks love them rafts 😉 liferaft is running over a robust TLS transport with peer discovery and HMAC-based authentication.

• Health checks, real-time and voting-based.

• Self-healing clusters. When the number of active nodes in a cluster falls below a given threshold, new nodes will be started automatically on the least loaded server(s) in a split second. Spare pools are supported.

• Events and triggers Just about everything is an event that you can hook up your trigger to.

• KISS. Hacking up your own plugin is definitely not a rocket science.

Featured extensions

🚀 clusterduck-dashboard — A full-fledged dashboard built with React and Websocket.

clusterduck-redis — Redis health checks and envoy-based balancing

🚀 clusterduck-http — HTTP/Websocket health checks and haproxy/nginx support.

Table Of Contents

• Installation
• Command-line interface
• Configuration
• Events
  • Node events
  • Cluster events
• Transports

Installation

Node 15.x is recommended.

npm i -g clusterduck

Alternatively, you can clone the repo and link the dependencies which is useful for development purposes:

git clone [e-mail]:kakserpom/clusterduck.git
cd clusterduck
node link

TLS

If you want to enable TLS for Raft, run this to generate certificates:

clusterduck gen-tls

Command-line interface

Run the clusterduck command to see if it all works for you.

If you want to daemonize it, run clusterduck -d

If you want to stop a running daemon, run clusterduck stop

For debugging purposes use DEBUG environmental variable: DEBUG=* clusterduck

Configuration

The default config file path is /etc/clusterduck/clusterduck.yaml

Clusters

Let's define a Redis cluster named my_redis_cluster:

clusters:
  
  my_redis_cluster:
    type: clusterduck-redis

Nodes

Then let's define some nodes:

    # List of nodes
    nodes:
      - addr: 127.0.0.1:6379
      - addr: 127.0.0.1:6380

Note that you can omit this altogether if you want to only add nodes dynamically.

Health checks

Now let's set up a simple health check.

    health_checks:
      - type: basic
        timeout: 1s
        interval: 10s
        interval_after_fail: 1s
        commands:
          - [ 'SET', 'x', 'y' ]

Now every 10 secs each node in the cluster will get checked on. If the check fails, a retry happens after 1 sec.

Triggers

Now let's live export the list of active nodes:

    triggers:
      - on: [ active ]
        do:
          - type: shell
            cwd: /tmp
            commands:
              - "echo $nodes_active_addrs > active_nodes.json"

This will make sure that /tmp/nodes_list always contains a current list of alive nodes.

Events

Cluster events

Event	Description
changed	Set of nodes has changed

Node events

Event	Description
state	Node state has changed

Transports

transports:

Raft

  - type: raft
    address: tls://127.0.0.1:9911
    bootstrap: [ tls://127.0.0.1:9910 ]

Parameter	Description
address *	Address to listen
tls	Path pattern to key/cert files. Default is clusterduck.%s (relative to the config file directory)
bootstrap	List of node addresses to connect with.

Clusterduck instances will exchange peers and update bootstrap accordingly, but initial address is necessary.

HTTP

  - type: http
    listen: 8880

Parameter	Description
listen	Port to listen

Roadmap

• CLI
• Live config updates (i.e. more Commands)
• REST API

Transports

• express
• jayson, jayson-promise