I am trying to create a service that receives a web-hook response from an external service (say, Azure). This web-hook has a unique identifier in the body. On receiving the web-hook, the service retrieves the web-socket instance that corresponds to this unique identifier from memory and passes on the message to the respective web-socket client, and this information is in turn displayed in the frontend application to the user.

This approach works quite well with a single node instance running, but when we fire up multiple instances of this node server and add a load balancer, the web-socket connections are distributed across the instances. This leads to a problem where now the load balancer does not know which instance the web-hook needs to be sent to (since it does not know which instance is connected to the target client web-socket).

Are there any recommendations or advices to solve this issue?