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* increase test coverage * @node-redis to @redis * ugprade deps * fix benchmark * use 7.0 docker (not rc), update readmes, clean code, fix @-redis import * update readme * fix function in cluster * update docs Co-authored-by: Chayim <chayim@users.noreply.github.com> * Update clustering.md * add subpackages move warning * drop support for node 12 * upgrade deps * fix tsconfig.base.json Co-authored-by: Chayim <chayim@users.noreply.github.com>
78 lines
5.4 KiB
Markdown
78 lines
5.4 KiB
Markdown
# Clustering
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## Basic Example
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Connecting to a cluster is a bit different. Create the client by specifying some (or all) of the nodes in your cluster and then use it like a regular client instance:
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```typescript
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import { createCluster } from 'redis';
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const cluster = createCluster({
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rootNodes: [
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{
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url: 'redis://10.0.0.1:30001'
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},
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{
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url: 'redis://10.0.0.2:30002'
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}
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]
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});
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cluster.on('error', (err) => console.log('Redis Cluster Error', err));
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await cluster.connect();
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await cluster.set('key', 'value');
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const value = await cluster.get('key');
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```
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## `createCluster` configuration
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> See the [client configuration](./client-configuration.md) page for the `rootNodes` and `defaults` configuration schemas.
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| Property | Default | Description |
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|------------------------|---------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| rootNodes | | An array of root nodes that are part of the cluster, which will be used to get the cluster topology. Each element in the array is a client configuration object. There is no need to specify every node in the cluster, 3 should be enough to reliably connect and obtain the cluster configuration from the server |
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| defaults | | The default configuration values for every client in the cluster. Use this for example when specifying an ACL user to connect with |
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| useReplicas | `false` | When `true`, distribute load by executing readonly commands (such as `GET`, `GEOSEARCH`, etc.) across all cluster nodes. When `false`, only use master nodes |
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| maxCommandRedirections | `16` | The maximum number of times a command will be redirected due to `MOVED` or `ASK` errors |
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| nodeAddressMap | | Defines the [node address mapping](#node-address-map) |
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| modules | | Included [Redis Modules](../README.md#packages) |
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| scripts | | Script definitions (see [Lua Scripts](../README.md#lua-scripts)) |
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| functions | | Function definitions (see [Functions](../README.md#functions)) |
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## Node Address Map
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A node address map is required when a redis cluster is configured with addresses that are inaccessible by the machine running the redis client.
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This is a mapping of addresses and ports, with the values being the accessible address/port combination. Example:
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```javascript
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createCluster({
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rootNodes: [{
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url: '10.0.0.1:30001'
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}, {
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url: '10.0.0.2:30002'
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}],
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nodeAddressMap: {
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'10.0.0.1:30001': 'external-host-1.io:30001',
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'10.0.0.2:30002': 'external-host-2.io:30002'
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}
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});
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```
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> This is a common problem when using ElastiCache. See [Accessing ElastiCache from outside AWS](https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/accessing-elasticache.html) for more information on that.
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## Command Routing
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### Commands that operate on Redis Keys
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Commands such as `GET`, `SET`, etc. are routed by the first key, for instance `MGET 1 2 3` will be routed by the key `1`.
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### [Server Commands](https://redis.io/commands#server)
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Admin commands such as `MEMORY STATS`, `FLUSHALL`, etc. are not attached to the cluster, and must be executed on a specific node via `.getSlotMaster()`.
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### "Forwarded Commands"
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Certain commands (e.g. `PUBLISH`) are forwarded to other cluster nodes by the Redis server. This client sends these commands to a random node in order to spread the load across the cluster.
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