A simple Express-based RQLite Cluster Discovery Service.

rqlite-disco-express

Last update: 06/07/2017

RQLite is a lightweight, open-source distributed relational database, with SQLite as its storage engine. To form a RQLite cluster, the joining node must be supplied with the network address of some other node in the cluster.

To make all this easier, RQLite 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. As a convenience, a free Discovery Service for RQLite is hosted at discovery.rqlite.com.

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

How it works

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

disco-url parameter

By default, the Discovery Service is hosted at http://discovery.rqlite.com. To use this rqlite-disco-express Service when starting a node, the disco-url parameter must be set. The start node command pattern becomes:

rqlited -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:

rqlited -http-addr localhost:4001 -raft-addr localhost:4002 -disco-id b3da7185-725f-461c-b7a4-13f185bd5007 -disco-url http://myhost:8090 ~/node.1

File storage

For simplicity, this rqlite-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 see this post.

• 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 this rqlite-disco-express Service, simply use node js:

node ./main.js

Test

To test this rqlite-disco-express Service, simply use npm:

npm test

License

Copyright (c) 2017 Jacques Desodt. Licensed under MIT