libp2p is a modular networking stack. It's designed to be able to suit a variety of project needs. The configuration of libp2p is a key part of its structure. It enables you to bring exactly what you need, and only what you need. This document is a guide on how to configure libp2p for your particular project. Check out the [Configuration examples](#configuration-examples) section if you're just looking to leverage an existing configuration.
Regardless of how you configure libp2p, the top level [API](./API.md) will always remain the same. **Note**: if some modules are not configured, like Content Routing, using those methods will throw errors.
## Modules
`js-libp2p` acts as the composer for this modular p2p networking stack using libp2p compatible modules as its subsystems. For getting an instance of `js-libp2p` compliant with all types of networking requirements, it is possible to specify the following subsystems:
- Transports
- Multiplexers
- Connection encryption mechanisms
- Peer discovery protocols
- Content routing protocols
- Peer routing protocols
- DHT implementation
- Pubsub router
The libp2p ecosystem contains at least one module for each of these subsystems. The user should install and import the modules that are relevant for their requirements. Moreover, thanks to the existing interfaces it is easy to create a libp2p compatible module and use it.
After selecting the modules to use, it is also possible to configure each one according to your needs.
> In a p2p system, we need to interact with other peers in the network. Transports are used to establish connections between peers. The libp2p transports to use should be decided according to the environment where your node will live, as well as other requirements that you might have.
- [libp2p/js-libp2p-utp](https://github.com/libp2p/js-libp2p-utp) (Work in Progress)
You should take into consideration that `js-libp2p-tcp` and `js-libp2p-utp` are not available in a **browser** environment.
If none of the available transports fulfills your needs, you can create a libp2p compatible transport. A libp2p transport just needs to be compliant with the [Transport Interface](https://github.com/libp2p/js-interfaces/tree/master/src/transport).
If you want to know more about libp2p transports, you should read the following content:
> Libp2p peers will need to communicate with each other through several protocols during their life. Stream multiplexing allows multiple independent logical streams to share a common underlying transport medium, instead of creating a new connection with the same peer per needed protocol.
If none of the available stream multiplexers fulfills your needs, you can create a libp2p compatible stream multiplexer. A libp2p multiplexer just needs to be compliant with the [Stream Muxer Interface](https://github.com/libp2p/js-interfaces/tree/master/src/stream-muxer).
If you want to know more about libp2p stream multiplexing, you should read the following content:
If none of the available connection encryption mechanisms fulfills your needs, you can create a libp2p compatible one. A libp2p connection encryption protocol just needs to be compliant with the [Crypto Interface](https://github.com/libp2p/js-interfaces/tree/master/src/crypto).
If you want to know more about libp2p connection encryption, you should read the following content:
**Note**: `peer-discovery` services within transports (such as `js-libp2p-webrtc-star`) are automatically gathered from the `transport`, via it's `discovery` property. As such, they do not need to be added in the discovery modules. However, these transports can also be configured and disabled as the other ones.
If none of the available peer discovery protocols fulfills your needs, you can create a libp2p compatible one. A libp2p peer discovery protocol just needs to be compliant with the [Peer Discovery Interface](https://github.com/libp2p/js-interfaces/tree/master/src/peer-discovery).
If you want to know more about libp2p peer discovery, you should read the following content:
> Content routing provides a way to find where content lives in the network. It works in two steps: 1) Peers provide (announce) to the network that they are holders of specific content and 2) Peers issue queries to find where that content lives. A Content Routing mechanism could be as complex as a DHT or as simple as a registry somewhere in the network.
If none of the available content routing protocols fulfills your needs, you can create a libp2p compatible one. A libp2p content routing protocol just needs to be compliant with the [Content Routing Interface](https://github.com/libp2p/js-interfaces/tree/master/src/content-routing). **(WIP: This module is not yet implemented)**
If you want to know more about libp2p content routing, you should read the following content:
- https://docs.libp2p.io/concepts/content-routing
### Peer Routing
> Peer Routing offers a way to find other peers in the network by issuing queries using a Peer Routing algorithm, which may be iterative or recursive. If the algorithm is unable to find the target peer, it will return the peers that are "closest" to the target peer, using a distance metric defined by the algorithm.
If none of the available peer routing protocols fulfills your needs, you can create a libp2p compatible one. A libp2p peer routing protocol just needs to be compliant with the [Peer Routing Interface](https://github.com/libp2p/js-interfaces/tree/master/src/peer-routing). **(WIP: This module is not yet implemented)**
If you want to know more about libp2p peer routing, you should read the following content:
- https://docs.libp2p.io/concepts/peer-routing
### DHT
> A DHT can provide content and peer routing capabilities in a p2p system, as well as peer discovery capabilities.
The DHT implementation currently available is [libp2p/js-libp2p-kad-dht](https://github.com/libp2p/js-libp2p-kad-dht). This implementation is largely based on the Kademlia whitepaper, augmented with notions from S/Kademlia, Coral and mainlineDHT.
If this DHT implementation does not fulfill your needs and you want to create or use your own implementation, please get in touch with us through a github issue. We plan to work on improving the ability to bring your own DHT in a future release.
If you want to know more about libp2p DHT, you should read the following content:
> Publish/Subscribe is a system where peers congregate around topics they are interested in. Peers interested in a topic are said to be subscribed to that topic and should receive the data published on it from other peers.
If none of the available pubsub routers fulfills your needs, you can create a libp2p compatible one. A libp2p pubsub router just needs to be created on top of [libp2p/js-libp2p-pubsub](https://github.com/libp2p/js-libp2p-pubsub), which ensures `js-libp2p` API expectations.
If you want to know more about libp2p pubsub, you should read the following content:
When [creating a libp2p node](./API.md#create), the modules needed should be specified as follows:
```js
const modules = {
transport: [],
streamMuxer: [],
connEncryption: [],
contentRouting: [],
peerRouting: [],
peerDiscovery: [],
dht: dhtImplementation,
pubsub: pubsubImplementation
}
```
Moreover, the majority of the modules can be customized via option parameters. This way, it is also possible to provide this options through a `config` object. This config object should have the property name of each building block to configure, the same way as the modules specification.
Besides the `modules` and `config`, libp2p allows other internal options and configurations:
-`datastore`: an instance of [ipfs/interface-datastore](https://github.com/ipfs/interface-datastore/) modules.
- This is used in modules such as the DHT. If it is not provided, `js-libp2p` will use an in memory datastore.
- This is particularly useful if you want to reuse the same `peer-id`, as well as for modules like `libp2p-delegated-content-routing`, which need a `peer-id` in their instantiation.
-`announceFilter`: filter function used to filter announced addresses programmatically: `(ma: Array<multiaddr>) => Array<multiaddr>`. Default: returns all addresses. [`libp2p-utils`](https://github.com/libp2p/js-libp2p-utils) provides useful [multiaddr utilities](https://github.com/libp2p/js-libp2p-utils/blob/master/API.md#multiaddr-isloopbackma) to create your filters.
Dialing in libp2p can be configured to limit the rate of dialing, and how long dials are allowed to take. The dialer configuration object should have the following properties:
| Name | Type | Description |
|------|------|-------------|
| maxParallelDials | `number` | How many multiaddrs we can dial in parallel. |
| maxDialsPerPeer | `number` | How many multiaddrs we can dial per peer, in parallel. |
| dialTimeout | `number` | Second dial timeout per peer in ms. |
The Connection Manager prunes Connections in libp2p whenever certain limits are exceeded. If Metrics are enabled, you can also configure the Connection Manager to monitor the bandwidth of libp2p and prune connections as needed. You can read more about what Connection Manager does at [./CONNECTION_MANAGER.md](./CONNECTION_MANAGER.md). The configuration values below show the defaults for Connection Manager. See [./CONNECTION_MANAGER.md](./CONNECTION_MANAGER.md#options) for a full description of the parameters.
The Transport Manager is responsible for managing the libp2p transports life cycle. This includes starting listeners for the provided listen addresses, closing these listeners and dialing using the provided transports. By default, if a libp2p node has a list of multiaddrs for listenning on and there are no valid transports for those multiaddrs, libp2p will throw an error on startup and shutdown. However, for some applications it is perfectly acceptable for libp2p nodes to start in dial only mode if all the listen multiaddrs failed. This error tolerance can be enabled as follows:
| computeThrottleMaxQueueSize | `number` | How many messages a stat will queue before processing. |
| computeThrottleTimeout | `number` | Time in milliseconds a stat will wait, after the last item was added, before processing. |
| movingAverageIntervals | `Array<number>` | The moving averages that will be computed. |
| maxOldPeersRetention | `number` | How many disconnected peers we will retain stats for. |
The below configuration example shows how the metrics should be configured. Aside from enabled being `false` by default, the following default configuration options are listed below:
PeerStore persistence is disabled in libp2p by default. You can enable and configure it as follows. Aside from enabled being `false` by default, it will need an implementation of a [datastore](https://github.com/ipfs/interface-datastore). Take into consideration that using the memory datastore will be ineffective for persistence.
The threshold number represents the maximum number of "dirty peers" allowed in the PeerStore, i.e. peers that are not updated in the datastore. In this context, browser nodes should use a threshold of 1, since they might not "stop" properly in several scenarios and the PeerStore might end up with unflushed records when the window is closed.
| persistence | `boolean` | Is persistence enabled. |
| threshold | `number` | Number of dirty peers allowed. |
The below configuration example shows how the PeerStore should be configured. Aside from persistence being `false` by default, the following default configuration options are listed below:
Some Transports can be passed additional options when they are created. For example, `libp2p-webrtc-star` accepts an optional, custom `wrtc` implementation. In addition to libp2p passing itself and an `Upgrader` to handle connection upgrading, libp2p will also pass the options, if they are provided, from `config.transport`.
During Libp2p startup, transport listeners will be created for the configured listen multiaddrs. Some transports support custom listener options and you can set them using the `listenerOptions` in the transport configuration. For example, [libp2p-webrtc-star](https://github.com/libp2p/js-libp2p-webrtc-star) transport listener supports the configuration of its underlying [simple-peer](https://github.com/feross/simple-peer) ice server(STUN/TURN) config as follows:
Network Address Translation (NAT) is a function performed by your router to enable multiple devices on your local network to share a single IPv4 address. It's done transparently for outgoing connections, ensuring the correct response traffic is routed to your computer, but if you wish to accept incoming connections some configuration is necessary.
The NAT manager can be configured as follows:
```js
const node = await Libp2p.create({
config: {
nat: {
description: 'my-node', // set as the port mapping description on the router, defaults the current libp2p version and your peer id
enabled: true, // defaults to true
gateway: '192.168.1.1', // leave unset to auto-discover
externalIp: '80.1.1.1', // leave unset to auto-discover
ttl: 7200, // TTL for port mappings (min 20 minutes)
keepAlive: true, // Refresh port mapping after TTL expires
pmp: {
enabled: false, // defaults to false
}
}
}
})
```
##### Browser support
Browsers cannot open TCP ports or send the UDP datagrams necessary to configure external port mapping - to accept incoming connections in the browser please use a WebRTC transport.
##### UPnP and NAT-PMP
By default under nodejs libp2p will attempt to use [UPnP](https://en.wikipedia.org/wiki/Universal_Plug_and_Play) to configure your router to allow incoming connections to any TCP transports that have been configured.
[NAT-PMP](http://miniupnp.free.fr/nat-pmp.html) is a feature of some modern routers which performs a similar job to UPnP. NAT-PMP is disabled by default, if enabled libp2p will try to use NAT-PMP and will fall back to UPnP if it fails.
As libp2p is designed to be a modular networking library, its usage will vary based on individual project needs. We've included links to some existing project configurations for your reference, in case you wish to replicate their configuration:
- [libp2p-ipfs-nodejs](https://github.com/ipfs/js-ipfs/blob/master/packages/ipfs/src/core/runtime/libp2p-nodejs.js) - libp2p configuration used by js-ipfs when running in Node.js
- [libp2p-ipfs-browser](https://github.com/ipfs/js-ipfs/blob/master/packages/ipfs/src/core/runtime/libp2p-browser.js) - libp2p configuration used by js-ipfs when running in a Browser (that supports WebRTC)
If you have developed a project using `js-libp2p`, please consider submitting your configuration to this list so that it can be found easily by other users.
The [examples](../examples) are also a good source of help for finding a configuration that suits your needs.
