tiny-cluster-db v1.0.5

Tiny Cluster DB

Use case

You need to store Key-value data in your app but you don't have access to persistent storage. Works perfectly for Kubernetes, Docker Swarm, Hashicorp nomad and other distributed systems. Made for ContainerOS project.

How it works

Database

Database stores actual key-value-timestamp data. It streams all the updates via HTTP to any backup node connecting to it. Exchanges data with backup nodes on start. Can be only a single instance if you don't want your data to be corrupted. If you need multiple instances, you can have a single Database instance and talk to it via some kind of API.

Backup Node

It listens to the updates from Database and stores them in memory. 3 instances recommended.

Example

app.js

const { Database } = require('tiny-cluster-db');

//create an instance and bind it to port 9999, can be any port
const db = new Database({ port: 9999 })

//set a value
await db.set('my/key1', 'someval')
// get value and ts
const {ts, value} = await db.get('my/key2') 
// get only value
const onlyValue = await db.getValue('my/key') 

//get all values with key starting with 'my/'
const allMyVals = await db.getRecurse('my/')


//db.safeUpdate would execute update function only if it hasn't changed since ts
//if value changed, it would re-execute update function and save new value

await db.set('my/safepatch', 0)
const updaterFunc = function (val) {//accept old value
    return val+1//return new value
}
for (let i = 0; i < 30; i++) {
    //Can be executed concurrently
    //Of course you have to handle a promise rejection
    db.safeUpdate('my/safepatch', updaterFunc) 
}

//safeUpdate also great for lists
await db.set('my/list', []) 
//...
await db.safeUpdate('my/list', function(someList){
    someList.push({name: 'someName', age: 10})
    return someList
})

backupNode.js

const { BackupNode } = require('tiny-cluster-db');
new BackupNode({ 
    dbHost: 'myapp', //host of the database, can be localhost for testing purposes
    dbPort: 9999, //the same port you set in 'new Database(...)'
})