better solution

src/main/kotlin/io/emeraldpay/dshackle/SilentException.kt

@@ -15,6 +15,7 @@
  */
 package io.emeraldpay.dshackle
 
+import io.emeraldpay.dshackle.upstream.Selector
 import io.emeraldpay.grpc.Chain
 
 /**
@@ -30,4 +31,6 @@ open class SilentException(message: String) : Exception(message) {
     }
 
     class DataUnavailable(val code: String) : SilentException("Data is unavailable: $code")
+
+    class NoMatchingUpstream(matcher: Selector.LabelSelectorMatcher) : SilentException("No configured upstream matching selector [${matcher.describeInternal()}]")
 }

src/main/kotlin/io/emeraldpay/dshackle/rpc/NativeCall.kt

@@ -24,6 +24,7 @@ import io.emeraldpay.dshackle.SilentException
 import io.emeraldpay.dshackle.quorum.CallQuorum
 import io.emeraldpay.dshackle.quorum.NotLaggingQuorum
 import io.emeraldpay.dshackle.quorum.QuorumReaderFactory
+import io.emeraldpay.dshackle.startup.ConfiguredUpstreams
 import io.emeraldpay.dshackle.upstream.ApiSource
 import io.emeraldpay.dshackle.upstream.Multistream
 import io.emeraldpay.dshackle.upstream.MultistreamHolder
@@ -51,6 +52,7 @@ import java.util.EnumMap
 @Service
 open class NativeCall(
     @Autowired private val multistreamHolder: MultistreamHolder,
+    @Autowired private val configuredUpstreams: ConfiguredUpstreams,
     @Autowired private val signer: ResponseSigner
 ) {
 
@@ -150,6 +152,11 @@ open class NativeCall(
             return Flux.error(CallFailure(0, SilentException.UnsupportedBlockchain(request.chain.number)))
         }
 
+        val matcher = Selector.convertToMatcher(request.selector)
+        if (!configuredUpstreams.hasMatchingUpstream(chain, matcher)) {
+            return Flux.error(CallFailure(0, SilentException.NoMatchingUpstream(matcher)))
+        }
+
         val upstream = multistreamHolder.getUpstream(chain)
             ?: return Flux.error(CallFailure(0, SilentException.UnsupportedBlockchain(chain)))
 

src/main/kotlin/io/emeraldpay/dshackle/startup/ConfiguredUpstreams.kt

@@ -25,6 +25,7 @@ import io.emeraldpay.dshackle.upstream.CurrentMultistreamHolder
 import io.emeraldpay.dshackle.upstream.Head
 import io.emeraldpay.dshackle.upstream.HttpRpcFactory
 import io.emeraldpay.dshackle.upstream.MergedHead
+import io.emeraldpay.dshackle.upstream.Selector
 import io.emeraldpay.dshackle.upstream.Upstream
 import io.emeraldpay.dshackle.upstream.bitcoin.BitcoinRpcHead
 import io.emeraldpay.dshackle.upstream.bitcoin.BitcoinRpcUpstream
@@ -107,6 +108,11 @@ open class ConfiguredUpstreams(
         }
     }
 
+    fun hasMatchingUpstream(chain: Chain, matcher: Selector.LabelSelectorMatcher): Boolean =
+        config.upstreams.any { up ->
+            up.chain?.equals(chain.chainName, ignoreCase = true) ?: true && matcher.matches(up.labels)
+        }
+
     private fun buildDefaultOptions(config: UpstreamsConfig): HashMap<Chain, UpstreamsConfig.Options> {
         val defaultOptions = HashMap<Chain, UpstreamsConfig.Options>()
         config.defaultOptions.forEach { defaultsConfig ->

src/main/kotlin/io/emeraldpay/dshackle/upstream/FilteredApis.kt

@@ -156,10 +156,6 @@ class FilteredApis(
     }
 
     override fun subscribe(subscriber: Subscriber<in Upstream>) {
-        if (allUpstreams.none { matcher.matches(it) }) {
-            Flux.empty<Upstream>().subscribe(subscriber)
-            return
-        }
         // initially try only standard upstreams
         val first = Flux.fromIterable(primaryUpstreams)
         val second = Flux.fromIterable(secondaryUpstreams)

src/test/groovy/io/emeraldpay/dshackle/rpc/NativeCallSpec.groovy

@@ -24,6 +24,7 @@ import io.emeraldpay.dshackle.Global
 import io.emeraldpay.dshackle.quorum.QuorumReaderFactory
 import io.emeraldpay.dshackle.quorum.QuorumRpcReader
 import io.emeraldpay.dshackle.reader.Reader
+import io.emeraldpay.dshackle.startup.ConfiguredUpstreams
 import io.emeraldpay.dshackle.test.MultistreamHolderMock
 import io.emeraldpay.dshackle.test.TestingCommons
 import io.emeraldpay.dshackle.quorum.AlwaysQuorum
@@ -51,14 +52,17 @@ class NativeCallSpec extends Specification {
 
     ObjectMapper objectMapper = Global.objectMapper
 
-    def nativeCall(MultistreamHolder upstreams = null, ResponseSigner signer = null) {
+    def nativeCall(MultistreamHolder upstreams = null, ResponseSigner signer = null, ConfiguredUpstreams configuredUpstreams = null) {
         if (upstreams == null) {
             upstreams = Stub(MultistreamHolder)
         }
         if (signer == null) {
             signer = Stub(ResponseSigner)
         }
-        new NativeCall(upstreams, signer)
+        if (configuredUpstreams == null) {
+            configuredUpstreams = Stub(ConfiguredUpstreams)
+        }
+        new NativeCall(upstreams, configuredUpstreams, signer)
     }
 
     def "Tries router first"() {