Capability to configure both default `CallCredentials` and custom `SslContext` on netty `ManagedChannel`

The problem

I would like to create a netty ManagedChannel which has both a default CallCredentials and a custom SslContext.

I can do the former with

return NettyChannelBuilder.forTarget(
    target,
    CompositeChannelCredentials.create(TlsChannelCredentials.create(), callCredentials))
  .build();

and I can do the latter with

return NettyChannelBuilder.forTarget(target)
  .sslContext(sslContext)
  .build();

but I can’t see a way to do both at once.

Solution ideas

I can see two possible API additions which would achieve this.

1. Make it possible to configure an SslContext on a ChannelCredentials instance. I guess this couldn’t be done on TlsChannelCredentials since that’s in core and can’t depend on the netty SslContext, so it would have to be a netty-specific ChannelCredentials implementation. Then I could do something like

return NettyChannelBuilder.forTarget(
   target,
   CompositeChannelCredentials.create(NettyTlsChannelCredentials.create().withSslContext(sslContext), callCredentials))
 .build();

1. Make it possible to configure a default CallCredentials on a NettyChannelBuilder without a ChannelCredentials. Then I could do something like

return NettyChannelBuilder.forTarget(target)
  .defaultCallCredentials(callCredentials)
  .sslContext(sslContext)
  .build();

From what I’ve seen of the source code, 2. would probably be the easier change to make, but might fit in less well with the direction you want to take the API in.

My current workaround

The workaround we’re intending to use right now is to create a channel which has the correct SslContext but no default CallCredentials, and instead configure the CallCredentials directly on every stub I create. To make this easier, we’ll wrap the ManagedChannel and the CallCredentials together into an object of our own so that we can pass them around together. Something like

return GrpcChannelWithCallCredentials.create(
  NettyChannelBuilder.forTarget(target)
    .sslContext(sslContext)
    .build(),
  callCredentials);

where GrpcChannelWithCallCredentials is our wrapper class. This is a bit ugly, and involves a change in every bit of code where we create a stub, rather than being able to do it once where we create the channel.

[pete-gillin-privitar]

Thanks, that’s exactly what I wanted!

I guess the only issue here is the lack of discoverability of this class. If you’re tracking the docs update elsewhere, I’m happy to close this.

[sergiitk]

Documentation update is merged, so closing. If more information is provided or there’s a follow-up question, comment and we can reopen.