Integreat-transporter-redis NPM

Redis transporter for Integreat

Transporter that lets Integreat access content in a Redis database.

Getting started

Prerequisits

Requires node v18 and Integreat v1.0.

Installing and using

Install from npm:

npm install integreat-transporter-redis

Example of use:

import Integreat from 'integreat'
import redisbullTransporter from 'integreat-transport-redis'
import defs from './config'

const great = Integreat.create(defs, {
  transporters: { bull: redisTransporter() },
})

// ... and then dispatch actions as usual

Example source configuration:

{
  id: 'store',
  transporter: 'redis',
  auth: true,
  endpoints: [{
    options: {
      prefix: 'store',
      redis: { uri: 'redis://localhost:6379' },
      concurrency: 5
      useTypeAsPrefix: true // Default is `true`
    }
  }]
}

Available options:

useTypeAsPrefix: When set to true, the key will be made up of <type>:<id>, where type and id are properties on the action payload. Otherwise, the key will just be the id. Default is true.
prefix: A prefix used with all Redis keys. The prefix and the key will be separated by colon :. This prefix is added even when useTypeAsPrefix is true and comes in from of the type prefix. Default is no prefix.
concurrency: When fetching more keys in one action, you may specify how many to fetch in parallel with the concurrency option. The default is 1, meaning they will be fetching in sequence.
connectionTimeout: When set to a number of milliseconds, the Redis connection will be renewed after this timeout regardless of the state of the connection.
incoming: See Listening to changes below.

The available properties for the redis options object are as follow:

uri: The entire URL of Redis database
host: The Redis server hostname, default is localhost
port: The Redis server port, default is 6379
database: The Redis database number. Get this in Redis with SELECT index
auth: The Redis username as key and Redis password as secret
tls: Set to true to enable TLS. Default is false

You may choose to set the uri or specify the individual properties.

Redis options can also be given the credentials, i.e. the key and secret values, through an authenticator, like the options authenticator.

Fetching keys and values

You may fetch a single key from Redis with an id, several keys with an array of ids on id, or all keys starting with the prefix and type (if useTypeAsPrefix is true or not set). When fetching all keys, the keys will be sorted alphabetically.

By default, all fields on the key is fetched (using hgetall), but you may also fetch only the ids of the keys, by setting onlyIds to true. This does not make a lot of sense when you're fetching by id or ids, but could be useful when fetching a collection of keys.

Each key is fetched with a separate call to Redis, and you may specify how many to fetch in parallel with the concurrency option. The default is 1.

Fetching with patterns

In addition, you may fetch keys with a pattern, by setting the pattern option to a string, which may be one or more key "segments" separated by a colon ':'. This string is appended to the prefix and type (if useTypeAsPrefix is true or not set), and used as a pattern to fetch keys. Behind the scenes ':*' is appended too. For example, if the prefix is 'store' and the type is 'product', the pattern 'category:shoes' will fetch keys with the pattern 'store:product:category:shoes:*'.

The keys will be sorted alphabetically.

This may be combined with onlyIds to only fetch the ids of the matching keys.

Setting keys and values

When dispatching a SET action with one or more data items, the id of each data item will be used as the key in Redis, possibly prefixed with the prefix option and the type (if useTypeAsPrefix is true or not set).

Pinging Redis

To send a PING command to Redis, dispatch a SERVICE action with type ping:

const response = await great.dispatch({
  type: 'SERVICE',
  payload: { type: 'ping' },
})

response.data will hold the response data from Redis.

Listening to changes

The Redis transporter supports listening to changes in the database. To enable this, set the keyPattern in the incoming object on options. When the Integreat instance is set up, call listen() on the instance, and Integreat will dispatch SET action to changes to keys matching the pattern.

If a prefix is set on the service options, the keyPattern will be prefixed with it.

Note that we only listen to one keyPattern per service right now, and we disregard any keyPattern or prefix set on endpoint options. The dispatched action will match any endpoint regardless of what is specified on the endpoint. In the future we may allow different patterns and prefixes for different endpoints and direct the dispatched action to the correct endpoint, so only specify this on the service to make sure you are future compatible.

Also note that we only listen for hset changes for now.

If the Redis database is not configured to send notifications, it will be enabled automatically. The notify-keyspace-events 'Eh' are required, and will be added when listen() is run.