add: some useful metrics

internal/server/handlers.go

@@ -10,13 +10,20 @@ var (
 	RpcClient rpc.RpcClient
 )
 
-type BatchResponse struct {
-	SyncComplete bool
-	ChainName    string
-}
+type (
+	BatchHealthResponse struct {
+		SyncComplete bool
+		ChainName    string
+	}
 
-func batchCall() (bool, BatchResponse) {
-	var batchResponse BatchResponse
+	BatchMetricsResponse struct {
+		GasPrice    string
+		BlockNumber string
+	}
+)
+
+func batchHealthCall() (bool, BatchHealthResponse) {
+	var batchResponse BatchHealthResponse
 
 	rpcResponses, err := RpcClient.EthBatchRpcCall(jsonrpc.RPCRequests{
 		// The rpc call id here is guranteed to be in order of appearance starting from index 0
@@ -52,3 +59,42 @@ func batchCall() (bool, BatchResponse) {
 
 	return true, batchResponse
 }
+
+func batchMetricsCall() (bool, BatchMetricsResponse) {
+	var batchResponse BatchMetricsResponse
+
+	rpcResponses, err := RpcClient.EthBatchRpcCall(jsonrpc.RPCRequests{
+		// The rpc call id here is guranteed to be in order of appearance starting from index 0
+		jsonrpc.NewRequest("eth_gasPrice"),
+		jsonrpc.NewRequest("eth_blockNumber"),
+	})
+
+	if err != nil {
+		log.Error().
+			Err(err).
+			Str("module", "server").
+			Msg("error in batch responses")
+		return false, batchResponse
+	}
+
+	// Order and format isn't guranteed with batch calls therefore we individually process/transform each result in the map
+	if gasPrice, ok := rpcResponses[0]; ok {
+		// TODO: decode hex
+		val, err := gasPrice.GetString()
+		if err != nil {
+			return false, batchResponse
+		}
+		// If sync is complete the rpc result is false, however this call dones't gurantee all blocks have been imported
+		batchResponse.GasPrice = val
+	}
+
+	if blockNumber, ok := rpcResponses[1]; ok {
+		val, err := blockNumber.GetString()
+		if err != nil {
+			return false, batchResponse
+		}
+		batchResponse.BlockNumber = val
+	}
+
+	return true, batchResponse
+}

internal/server/router.go

@@ -1,7 +1,6 @@
 package server
 
 import (
-	"fmt"
 	"net/http"
 
 	"github.com/gin-gonic/gin"
@@ -20,9 +19,8 @@ func Start(port string, ginMode string) error {
 }
 
 func healthHandler(c *gin.Context) {
-	allOk, data := batchCall()
+	allOk, data := batchHealthCall()
 
-	fmt.Println(data.SyncComplete)
 	if !allOk {
 		// choose a better status code if available
 		c.JSON(http.StatusExpectationFailed, gin.H{
@@ -38,7 +36,18 @@ func healthHandler(c *gin.Context) {
 }
 
 func metricsHandler(c *gin.Context) {
+	allOk, data := batchMetricsCall()
+
+	if !allOk {
+		// choose a better status code if available
+		c.JSON(http.StatusExpectationFailed, gin.H{
+			"message": "could not get node metrics",
+		})
+		return
+	}
+
 	c.JSON(http.StatusOK, gin.H{
-		"ok": true,
+		"gasPrice":    data.GasPrice,
+		"blockNumber": data.BlockNumber,
 	})
 }