An Express-based Cluster Discovery Service.

disco-express

Last update: 11/11/2017

Continuul provides a cloud native distributed container database management solution for open-source databases. The solution is build upon the foundational work Docker and Kubernetes.

To form a Continuul cluster, the joining node must be supplied with the network address of some other node in the cluster.

To make all this easier, Continuul also supports discovery mode. In this mode each node registers its network address with an external service, and learns the join addresses of other nodes from the same service.

If you need your own Discovery Service with Node.js, here it is!

How it works

disco-express is based on the Express web framework. For more information on the Continuul clusters, see the Cluster Guidelines and Cluster Discovery Service docs.

disco-url parameter

To use the disco-express Service when starting a node, the disco-url parameter must be set. The start node command pattern becomes:

application -http-addr <node-ip>:<node-http-port> -raft-addr <node-ip>:<node-raft-port> -disco-id <cluster-disco-id> -disco-url <your-service-URL> <node-data-directory>

Example:

application -http-addr localhost:4001 -raft-addr localhost:4002 -disco-id b3da7185-725f-461c-b7a4-13f185bd5007 -disco-url http://myhost:8081 ~/node.1

File storage

For simplicity, this disco-express Service uses a file-based storage for the cluster data. Each cluster is stored in a file named <disco-id>.json. The contents of this file are the JSON string of the cluster data. For performance, these files are uploaded in a memory map on the fly.

Configuration

The configuration is written in the ./config/config.js file.

Express

• protocol: http or https. For SSL configuration, see below.
• port: the service port number.

SSL

For more information on Express and SSL, please follow instructions for using SSL with Express 4.

• key: your private key. It is read from a file, default is ./config/privatekey.pem.
• cert: your certificate. It is read from a file, default is ./config/certificate.pem.
• passphrase: if necessary, the passphrase string.

File storage

• path: the data files path on disk.
• encoding: the encoding used. utf8 is a good example.

Run the Service

To run the disco-express Service, simply use node js:

node app.js

Or to run the Docker:

docker run -ti continuul/disco-express:latest

Building

To build the disco-express Service, simply use npm:

npm install

To build the disco-express Docker, simply use docker:

docker build -t continuul/disco-express:latest

Test

To test the disco-express Service, simply use npm:

npm test

License

Copyright (c) 2017 The Continuul Authors. Licensed under Apache License 2.0