ethereum pos doc and some config naming

docs/04-upstream-config.adoc

@@ -17,6 +17,13 @@ Those protocols can be configures with additional security, TLS and authenticati
 - Most of Ethereum nodes support WebSocket connection, in addition to the JSON RPC.
 If it's available on your node, it's suggested to configure both JSON RPC and WebSocket connection
 
+==== Ethereum PoS
+
+- The support for PoS Ethereum isn't fully implemented yet. However, we support it in a simplified way.
+As we can no longer rely on the difficulty parameter of a block for fork choice algorithm we implement upstream rating.
+In short terms, we just consider the upstream with the highest rating to be always correct when reporting its head.
+Unless it's down then we will fallback on the upstream with the second highest rating, etc.
+
 ==== Bitcoin
 
 - Bitcoind needs to be configured to index/track addresses that you're going to request.
@@ -72,6 +79,15 @@ cluster:
             basic-auth:
               username: ${INFURA_USER}
               password: ${INFURA_PASSWD}
+    - id: ethereum-pos
+      chain: ropsten
+      connection:
+        ethereum-pos:
+            execution:
+              rpc:
+                url: ${ROPSTEN_NODE_RPC_URL}
+              ws:
+                url: ${ROPSTEN_NODE_WS_URL}
 ----
 
 There are two main segments for upstreams configuration:

docs/reference-configuration.adoc

@@ -769,6 +769,22 @@ Default is 15Mb
 
 |===
 
+==== PoS Ethereum Connection Options
+.Connection Config for PoS Ethereum Upstream
+[cols="2a,5"]
+|===
+| Option | Description
+
+| `execution`
+a| Here you can specify any option from plain ethereum connection options listed above +
+This is your connection to an execution layer of PoS Ethereum
+
+| `upstream-rating`
+a| Rating for this upstream. We will always consider the head of the chain to be +
+the latest block we saw from the upstream with the highest rating.
+
+|===
+
 ==== Bitcoin Connection Options
 
 .Connection Config for Bitcoin Upstream

src/main/kotlin/io/emeraldpay/dshackle/config/UpstreamsConfig.kt

@@ -102,7 +102,7 @@ open class UpstreamsConfig {
         var host: String? = null
         var port: Int = 0
         var auth: AuthConfig.ClientTlsAuth? = null
-        var nodeRating: Int = 0
+        var upstreamRating: Int = 0
     }
 
     class EthereumConnection : RpcConnection() {
@@ -117,7 +117,7 @@ open class UpstreamsConfig {
 
     class EthereumPosConnection : UpstreamConnection() {
         var execution: EthereumConnection? = null
-        var blockPriority: Int = 0
+        var upstreamRating: Int = 0
     }
 
     data class BitcoinZeroMq(

src/main/kotlin/io/emeraldpay/dshackle/config/UpstreamsConfigReader.kt

@@ -107,7 +107,7 @@ class UpstreamsConfigReader(
                     val connection = UpstreamsConfig.GrpcConnection()
                     upstream.connection = connection
                     getValueAsInt(connConfigNode, "node-rating")?.let {
-                        connection.nodeRating = it
+                        connection.upstreamRating = it
                     }
                     getValueAsString(connConfigNode, "host")?.let {
                         connection.host = it
@@ -170,8 +170,8 @@ class UpstreamsConfigReader(
         getMapping(connConfigNode, "execution")?.let {
             connection.execution = readEthereumConnection(it)
         }
-        getValueAsInt(connConfigNode, "block-priority")?.let {
-            connection.blockPriority = it
+        getValueAsInt(connConfigNode, "node-rating")?.let {
+            connection.upstreamRating = it
         }
         return connection
     }

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

@@ -159,7 +159,7 @@ open class ConfiguredUpstreams(
             return null
         }
         val urls = ArrayList<URI>()
-        val connectorFactory = buildEthereumConnectorFactory(execution, chain, urls, NoChoiceWithPriorityForkChoice(conn.blockPriority))
+        val connectorFactory = buildEthereumConnectorFactory(execution, chain, urls, NoChoiceWithPriorityForkChoice(conn.upstreamRating))
         val methods = buildMethods(config, chain)
         if (connectorFactory == null) {
             return null
@@ -256,7 +256,7 @@ open class ConfiguredUpstreams(
             endpoint.port,
             endpoint.auth,
             fileResolver,
-            endpoint.nodeRating
+            endpoint.upstreamRating
         ).apply {
             timeout = options.timeout
         }