Listener is not ready yet (Websocket and pubsub discovery)

[sfroment]

Hello 👋

• Version: @libp2p+websockets@9.1.0

• Platform: MacOS (but the bug will be present on every platform)

Severity: Medium/High

Description: So while working on Topology ts-drp. I encounter this

/node_modules/.pnpm/@libp2p+websockets@9.1.0/node_modules/@libp2p/websockets/src/listener.ts:347
      throw new Error('Listener is not ready yet')
            ^


Error: Listener is not ready yet
    at WebSocketListener.getAddrs (/node_modules/.pnpm/@libp2p+websockets@9.1.0/node_modules/@libp2p/websockets/src/listener.ts:347:13)
    at DefaultTransportManager.getAddrs (/node_modules/.pnpm/libp2p@2.4.2/node_modules/libp2p/src/transport-manager.ts:136:40)
    at AddressManager.getAddressesWithMetadata (/node_modules/.pnpm/libp2p@2.4.2/node_modules/libp2p/src/address-manager/index.ts:358:40)
    at AddressManager.getAddresses (/node_modules/.pnpm/libp2p@2.4.2/node_modules/libp2p/src/address-manager/index.ts:304:29)
    at @libp2p/pubsub-peer-discovery._broadcast (/node_modules/.pnpm/@libp2p+pubsub-peer-discovery@11.0.1/node_modules/@libp2p/pubsub-peer-discovery/src/index.ts:247:44)
    at @libp2p/pubsub-peer-discovery.afterStart (/node_modules/.pnpm/@libp2p+pubsub-peer-discovery@11.0.1/node_modules/@libp2p/pubsub-peer-discovery/src/index.ts:203:5)
    at <anonymous> (/node_modules/.pnpm/libp2p@2.4.2/node_modules/libp2p/src/components.ts:80:6)
    at Array.map (<anonymous>)
    at Proxy._invokeStartableMethod (/node_modules/.pnpm/libp2p@2.4.2/node_modules/libp2p/src/components.ts:77:10)
    at Proxy.afterStart (/node_modules/.pnpm/libp2p@2.4.2/node_modules/libp2p/src/components.ts:96:9)

The usage of pubsubdiscovery is broken if you only use the ws transport. As not the pubsub won't be able to call this.addressManager.getAddresses() in the afterStart like it does right now.
The problem is both the late init of the WS server, and the fact that all the after start are called at the same time in components.ts

  private async _invokeStartableMethod (methodName: 'beforeStart' | 'start' | 'afterStart' | 'beforeStop' | 'stop' | 'afterStop'): Promise<void> {
    await Promise.all(
      Object.values(this.components)
        .filter(obj => isStartable(obj))
        .map(async (startable: Startable) => {
          await startable[methodName]?.()
        })
    )
  }

Steps to reproduce the error: Just add this unit test in packages/transport-websockets/test/node.ts

class TestPeerDiscovery extends TypedEventEmitter<PeerDiscoveryEvents> implements PeerDiscovery, Startable {
  private readonly addressManager: AddressManager

  constructor (components: {
    addressManager: AddressManager
  }) {
    super()
    this.addressManager = components.addressManager
  }

  async start (): Promise<void> {
  }

  async stop (): Promise<void> { }

  afterStart (): void {
    this.addressManager.getAddresses()
  }

  readonly [Symbol.toStringTag] = '@libp2p/test-peer-discovery'
}

describe('discovery-websockets', () => {
  it('should discover peers over websockets', async () => {
    const libp2p = await createLibp2p({
      addresses: {
        listen: [
          '/ip4/0.0.0.0/tcp/0/ws'
        ]
      },
      peerDiscovery: [(component: {
        addressManager: AddressManager
      }) => new TestPeerDiscovery(component)],
      transports: [
        webSockets()
      ]
    })

    await libp2p.start()
  })
})

I've made a fix but I don't fix this is the one you'd want to add in the repo.
So:

• we can change the way the conn manager is listening and make the listen in start ?
• change the way components.ts will call the afterStart so it's not in a promise all but rather in an "ordered" way
• change the way the WS server is construct/inited ?

What ever solution you'll decide to implement could you please ping me so I can see the way you'll do it 🙏
Nevertheless here's my shot at it: #2903

[achingbrain]

I think we should just make getAddrs return an empty array if this.server.address() returns a falsey value instead of throwing. I think this is reasonable, as long as .listen has been called already.

[sfroment]

@achingbrain Thanks ! As long as it don't break anything else I'd be happy with it :)

[achingbrain]

The fix for this has shipped in @libp2p/websockets@9.1.1 - please try it out!

[sfroment]

Thanks for releasing that fast ! You're a beast !