Add a method for resolver to report error

[menghanl]

If a resolver could not resolve a name, there's currently no way to report error back to ClientConn, and RPCs on the ClientConn will fail with timeout.

This method allows resolver to report error to ClientConn, and failfast RPCs should fail with this error (or RPC errors that contain info from this error).

[peats-bond]

Can we get an update on the status/timeline of this? In #2785, @menghanl you said that this was being actively worked on.

[menghanl]

The plan was to do this after #2732, because they both add features to resolver/balancer. But #2732 got delayed by discussion on some details.
This is not necessary blocked by that PR, I think we can do this first. I will try to put something together this week.

[peats-bond]

Perfect, thanks for the update!

[peats-bond]

@menghanl any update?

[menghanl]

The changes are in #2831. It might need more discussion.
Please take a look and comment. Thanks!

[menghanl]

This error handling logic in resolver gets complicated with service config. (e.g. What to do if we get an error fetching addresses, but get service config? Do we apply the service config or also drop it? What if we get addresses but failed for service config?). We may end up needing two errors.

This is still under discussion, we will send an update when there's a conclusion.

[peats-bond]

Gentle ping :)

[menghanl]

@dfawley is working on this now. The PR will support this and also errors for service config. The PR should be ready soon (within two weeks).

[jeffbean]

any updates would be great . trying to estimate if this how much risk this is to our project.

[dfawley]

This is PR #2951.

[jeffbean]

This is PR #2951.

🤦‍♂ ty! I need more coffee.

[stale]

This issue is labeled as requiring an update from the reporter, and no update has been received after 7 days. If no update is provided in the next 7 days, this issue will be automatically closed.

[dfawley]

Something seems to be broken. I'm going to disable the stale bot for now.