imp(rpc) Add support for EVM RPC metrics (#1378)

* imp(rpc) Add support for EVM RPC metrics

- Support --metrics flag
- Add EVM rpc metrics server config

* Update as per PR feedback

Co-authored-by: Freddy Caceres <facs95@gmail.com>

.github/workflows/semgrep.yml

@@ -32,7 +32,7 @@ jobs:
             go.mod
             go.sum
       - uses: actions/checkout@v3
-      - run: semgrep scan --sarif --output=semgrep.sarif
+      - run: semgrep scan --sarif --output=semgrep.sarif --config auto
         env:
           # Upload findings to GitHub Advanced Security Dashboard [step 1/2]
           SEMGREP_APP_TOKEN: ${{ secrets.SEMGREP_APP_TOKEN }}

CHANGELOG.md

@@ -60,6 +60,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (ledger) [#1277](https://github.com/evmos/ethermint/pull/1277) Add Ledger preprocessing transaction hook for EIP-712-signed Cosmos payloads.
 * (rpc) [#1296](https://github.com/evmos/ethermint/pull/1296) Add RPC Backend unit tests.
 * (rpc) [#1352](https://github.com/evmos/ethermint/pull/1352) Make the grpc queries run concurrently, don't block the consensus state machine.
+* (rpc) [#1378](https://github.com/evmos/ethermint/pull/1378) Add support for EVM RPC metrics
 
 ### Bug Fixes
 

server/config/config.go

@@ -25,6 +25,9 @@ const (
 	// DefaultJSONRPCWsAddress is the default address the JSON-RPC WebSocket server binds to.
 	DefaultJSONRPCWsAddress = "0.0.0.0:8546"
 
+	// DefaultJsonRPCMetricsAddress is the default address the JSON-RPC Metrics server binds to.
+	DefaultJSONRPCMetricsAddress = "0.0.0.0:6065"
+
 	// DefaultEVMTracer is the default vm.Tracer type
 	DefaultEVMTracer = ""
 
@@ -110,6 +113,8 @@ type JSONRPCConfig struct {
 	MaxOpenConnections int `mapstructure:"max-open-connections"`
 	// EnableIndexer defines if enable the custom indexer service.
 	EnableIndexer bool `mapstructure:"enable-indexer"`
+	// MetricsAddress defines the metrics server to listen on
+	MetricsAddress string `mapstructure:"metrics-address"`
 }
 
 // TLSConfig defines the certificate and matching private key for the server.
@@ -211,6 +216,7 @@ func DefaultJSONRPCConfig() *JSONRPCConfig {
 		AllowUnprotectedTxs: DefaultAllowUnprotectedTxs,
 		MaxOpenConnections:  DefaultMaxOpenConnections,
 		EnableIndexer:       false,
+		MetricsAddress:      DefaultJSONRPCMetricsAddress,
 	}
 }
 
@@ -319,6 +325,7 @@ func GetConfig(v *viper.Viper) (Config, error) {
 			HTTPIdleTimeout:    v.GetDuration("json-rpc.http-idle-timeout"),
 			MaxOpenConnections: v.GetInt("json-rpc.max-open-connections"),
 			EnableIndexer:      v.GetBool("json-rpc.enable-indexer"),
+			MetricsAddress:     v.GetString("json-rpc.metrics-address"),
 		},
 		TLS: TLSConfig{
 			CertificatePath: v.GetString("tls.certificate-path"),

server/config/toml.go

@@ -73,6 +73,10 @@ max-open-connections = {{ .JSONRPC.MaxOpenConnections }}
 # EnableIndexer enables the custom transaction indexer for the EVM (ethereum transactions).
 enable-indexer = {{ .JSONRPC.EnableIndexer }}
 
+# MetricsAddress defines the EVM Metrics server address to bind to. Pass --metrics in CLI to enable
+# Prometheus metrics path: /debug/metrics/prometheus
+metrics-address = "{{ .JSONRPC.MetricsAddress }}"
+
 ###############################################################################
 ###                             TLS Configuration                           ###
 ###############################################################################

server/flags/flags.go

@@ -49,6 +49,10 @@ const (
 	JSONRPCAllowUnprotectedTxs = "json-rpc.allow-unprotected-txs"
 	JSONRPCMaxOpenConnections  = "json-rpc.max-open-connections"
 	JSONRPCEnableIndexer       = "json-rpc.enable-indexer"
+	// JSONRPCEnableMetrics enables EVM RPC metrics server.
+	// Set to `metrics` which is hardcoded flag from go-ethereum.
+	// https://github.com/ethereum/go-ethereum/blob/master/metrics/metrics.go#L35-L55
+	JSONRPCEnableMetrics = "metrics"
 )
 
 // EVM flags

server/start.go

@@ -33,6 +33,8 @@ import (
 	"github.com/cosmos/cosmos-sdk/server/rosetta"
 	crgserver "github.com/cosmos/cosmos-sdk/server/rosetta/lib/server"
 
+	ethmetricsexp "github.com/ethereum/go-ethereum/metrics/exp"
+
 	"github.com/cosmos/cosmos-sdk/client"
 	"github.com/cosmos/cosmos-sdk/client/flags"
 	pruningtypes "github.com/cosmos/cosmos-sdk/pruning/types"
@@ -171,6 +173,7 @@ which accepts a path for the resulting pprof file.
 	cmd.Flags().Int32(srvflags.JSONRPCBlockRangeCap, config.DefaultBlockRangeCap, "Sets the max block range allowed for `eth_getLogs` query")
 	cmd.Flags().Int(srvflags.JSONRPCMaxOpenConnections, config.DefaultMaxOpenConnections, "Sets the maximum number of simultaneous connections for the server listener") //nolint:lll
 	cmd.Flags().Bool(srvflags.JSONRPCEnableIndexer, false, "Enable the custom tx indexer for json-rpc")
+	cmd.Flags().Bool(srvflags.JSONRPCEnableMetrics, false, "Define if EVM rpc metrics server should be enabled")
 
 	cmd.Flags().String(srvflags.EVMTracer, config.DefaultEVMTracer, "the EVM tracer type to collect execution traces from the EVM transaction execution (json|struct|access_list|markdown)") //nolint:lll
 	cmd.Flags().Uint64(srvflags.EVMMaxTxGasWanted, config.DefaultMaxTxGasWanted, "the gas wanted for each eth tx returned in ante handler in check tx mode")                                 //nolint:lll
@@ -340,6 +343,12 @@ func startInProcess(ctx *server.Context, clientCtx client.Context, appCreator ty
 		app.RegisterTendermintService(clientCtx)
 	}
 
+	// Enable metrics if JSONRPC is enabled and --metrics is passed
+	// Flag not added in config to avoid user enabling in config without passing in CLI
+	if config.JSONRPC.Enable && ctx.Viper.GetBool(srvflags.JSONRPCEnableMetrics) {
+		ethmetricsexp.Setup(config.JSONRPC.MetricsAddress)
+	}
+
 	var idxer ethermint.EVMTxIndexer
 	if config.JSONRPC.EnableIndexer {
 		idxDB, err := OpenIndexerDB(home, server.GetAppDBBackend(ctx.Viper))