Small refactor of tests:
- Add a channel to remoteBalancer on which to send received stats messages
- Change runAndGetStats to runAndCheckStats to allow for faster successful test
runs (no longer need to sleep for one whole second per test).
- Remove redundant leak check from runAndCheckStats, otherwise excess load
report messages not read from the channel will result in an infinite loop.
- Add String method to rpcStats to avoid data race between merging and printing.
This is necessary because there's another way to select grpclb (by specifying grpclb in service config's balancing policy field). So it's possible that grpclb is picked, but resolver doesn't have any balancer addresses.
When an update without balancer address is received, grpclb closes the underlying ClientConn to remote balancer, and enters fallback mode.
Note that grpclb waits until the ClientConn and the RPC goroutines are actually closed to do the fallback work. This can avoid race caused by async close.
With pickfirst, the same SubConn is reused, only addresses are updated.
But backends and fallbacks may need different credentials. This change
force-removes all SubConns when switching fallback.
Keep the drop index from the previous picker when regenerating picker due to
subchannel state change. Only reset the drop index when picker is regenerated
because of a serverlist update.
fixes#2623
Google default creds is a combo of ALTS, TLS and OAuth2. The right set of creds will be picked to use based on environment.
This PR contains:
- A new `creds.Bundle` type
- changes to use it in ClientConn and transport
- dial option to set the bundle for a ClientConn
- balancer options and NewSubConnOption to set it for SubConn
- Google default creds implementation by @cesarghali
- grpclb changes to use different creds mode for different servers
- interop client changes for google default creds testing
Fixes https://github.com/grpc/grpc-go/issues/2161
I introduced `serverTerminatedConnectionErr `, because I wanted `callRemoteBalancer` to still returns error on a terminated connections. Its client, which is function `watchRemoteBalancer` can decide how to log this error.
When remote grpclb-server terminates the connection, don't log it as
error. Instead, log it as info.
It is natural for servers to terminate long lived grpc streaming
connections. Two sample reasons to do this are: load balancing and
deployment of a new version. Therefore client of grpclb-server shouldn't
recognise this situation as an error.
This PR splits out grpclb from grpc. I have made the PR in several commits so you can see more clearly the steps that happened.
There are a few possibly contentious points that I would like to make clear up front:
* grpclb will no longer autoload as a load balancer. I think this is okay, as service config is not widely (at all?) used, and I believe this is the only way to access it.
* `internal` is used more, as a way of having code shared between packages without exposing types
* ConnectivityStateEvaluator, as used by grpclb, is no longer thread safe. I believe there is an outer mutex that guards access, but I want to point out this subtle change up here.
All but one tests pass with this, due to another cyclic dependency. I can fix this, but it is a little more widely scoped (such as exposing grpc.server and grpc.errorDesc in the internal package). This PR is a nearly-passing sample of that last step to get this working.
PTAL @menghanl @dfawley
Mikhail Mazurskiy