Document missing options

[hermanbanken]

• grpc.max_connection_age_grace_ms
• grpc.max_connection_age_ms

We were bitten by these missing options. One could argue that it is unclear how to best setup gRPC round robin load balancing in a Kubernetes cluster, but that is besides the point. We were using these options, switched from grpc to grpc-js and suddenly the load was only coming to a few instances, making the service 10x as slow. I'd argue this is missing from the "migration" list in the readme too: https://www.npmjs.com/package/@grpc/grpc-js.

[hermanbanken]

I wrote this in the readme:

If you were using grpc.max_connection_age_grace_ms or grpc.max_connection_age_ms, please note that these options are not implemented. If you are using this for load balancing, you should migrate to proper client-side load balancing or service configs.

But I have to say, I do not know where to find proper client-side load balancing or service configs documentation myself... I'd like to add a link to some good documentation there.

[murgatroid99]

I don't see any value in calling out specific options that are not implemented. All of the options not listed are not implemented; there is nothing special about the ones you added the note about.

Similarly, I don't think we should call out specific options in the README. We could instead have a general note referencing the list of supported options.

[hermanbanken]

I don't see any value in calling out specific options that are not implemented. All of the options not listed are not implemented; there is nothing special about the ones you added the note about.

Similarly, I don't think we should call out specific options in the README. We could instead have a general note referencing the list of supported options.

I wholly disagree. If you are coming from the grpc library, and you read this:

Documentation specifically for the @grpc/grpc-js package is currently not available. However, documentation is available for the grpc package, and the two packages contain mostly the same interface. There are a few notable differences, however, and these differences are noted in the "Migrating from grpc" section below.

Then you expect everything to be supported. From that moment on, everything unsupported I expect to be listed explicitly.

The value in adding this is that for real production use cases (the ones with actual load) there ain't any new unexpected behaviour. This cost us easily 2 hours already (multiple people investigating this in parallel) and multiply that by everyone that is using these options and you have substantial value.

[murgatroid99]

I think it would be reasonable to migrate the list of supported options from that linked document to the README. However, I don't think it's practical to maintain a list of every option the library doesn't support, and I think it would be misleading to specifically call out only some unsupported options.