node/grpc: Return to passthrough address resolution scheme

979811e switched SN-to-SN gRPC dial
approach from 'passthrough' resolution scheme (used by `grpc.Dial*`
functions) to the `dns` one (`grpc.NewClient`). This was not
intentional, but it did cause visible changes in behavior. The DNS
resolver began to introduce time costs into processing. This became
especially noticeable on the test macOS env, where delays reached 10s
causing tests to fall on deadline. On Linux, delays also increased, but
by negligible amounts.

This returns SN to using global 'passthrough' resolver.

Fixes #3250.

Signed-off-by: Leonard Lyubich <[email protected]>

Author: cthulhu-rider

CHANGELOG.md

@@ -34,6 +34,7 @@ Changelog for NeoFS Node
 - Race between basic income processing stages leading to distribution failures in some cases (#3338)
 - Wallet password logged by IR in some error cases (#3340)
 - Embedded CN not stopped properly in some error cases potentially leading to inconsistent blockchain DB state (#3340)
+- SN gRPC dialer switched from problematic `dns` address resolver to the `passthrough` one (#3334)
 
 ### Changed
 - IR calls `ObjectService.SearchV2` to select SG objects now (#3144)

cmd/neofs-node/grpc.go

@@ -14,9 +14,13 @@ import (
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/keepalive"
+	"google.golang.org/grpc/resolver"
 )
 
 func initGRPC(c *cfg) {
+	// although docs state that 'passthrough' is set by default, it should be set explicitly for activation
+	resolver.SetDefaultScheme("passthrough")
+
 	if c.cfgMorph.client == nil {
 		initMorphComponents(c)
 	}