Add configuration phase before http/rpc/ws servers launched

There is a case when microservice should get/request some configuration (or load initial data from db to memory storage) from separate config service before his servers( http/rpc/ws) will be launched. Would be cool to have an opportunity to delay nest servers launch providing some function that returns Observable. This function should has access to app services and http/rpc requests to get/load initial data. Also there is related issue - what if nest servers config (e.x. launch ports) should be requested from separate config service (http/rpc request). Currently it requires non-framework code that would wrap nest launch before configs loaded.

[kamilmysliwiec]

Hey guys, In the nearest release it’d be possible to create an async components (factories & values). All components, which depends on async components, would be also async, so you can use them as a some kind of configuration phase.

{
     provide: 'AsyncDatabaseConnection',
     useFactory: async (...args): Promise<any> => {

     },
     inject: [...]
},

Those async components are just promises, which have to be resolved before http/rpc/ws servers launch and may be injected into another components.

[kamilmysliwiec]

Hi @artaommahe, A little bit more about async components is available here