Make runner fail if proxy is not specified when scan is websocket

services/runner/check.go

@@ -0,0 +1,32 @@
+package runner
+
+import (
+	"fmt"
+	"net/url"
+)
+
+// CheckProxyAgainstScan checks given proxy URL against the scan API.
+// The proxy API must specified as HTTP(s) when the scan API is WebSocket.
+func CheckProxyAgainstScan(scan, proxy string) error {
+	scanUrl, err := url.Parse(scan)
+	if err != nil {
+		return fmt.Errorf("invalid scan api url: %v", err)
+	}
+	// nothing to check if scan is already not websocket
+	if !(scanUrl.Scheme == "ws" || scanUrl.Scheme == "wss") {
+		return nil
+	}
+
+	if len(proxy) == 0 {
+		return ErrBadProxyAPI
+	}
+	proxyUrl, err := url.Parse(proxy)
+	if err != nil {
+		return fmt.Errorf("invalid proxy api url: %v", err)
+	}
+	// and proxy api must be either http or https
+	if !(proxyUrl.Scheme == "http" || proxyUrl.Scheme == "https") {
+		return ErrBadProxyAPI
+	}
+	return nil
+}

services/runner/check_test.go

@@ -0,0 +1,54 @@
+package runner
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestCheckProxyAgainstScan(t *testing.T) {
+	testCases := []struct {
+		name  string
+		scan  string
+		proxy string
+		valid bool
+	}{
+		{
+			name:  "scan is http",
+			scan:  "http://foo.bar",
+			proxy: "",
+			valid: true,
+		},
+		{
+			name:  "scan is websocket, proxy is empty",
+			scan:  "wss://foo.bar",
+			proxy: "",
+			valid: false,
+		},
+		{
+			name:  "scan is websocket, proxy is websocket",
+			scan:  "wss://foo.bar",
+			proxy: "wss://foo.bar",
+			valid: false,
+		},
+		{
+			name:  "scan is websocket, proxy is http",
+			scan:  "wss://foo.bar",
+			proxy: "http://any.thing",
+			valid: true,
+		},
+	}
+
+	for _, testCase := range testCases {
+		t.Run(testCase.name, func(t *testing.T) {
+			r := require.New(t)
+
+			err := CheckProxyAgainstScan(testCase.scan, testCase.proxy)
+			if testCase.valid {
+				r.NoError(err)
+			} else {
+				r.Error(err)
+			}
+		})
+	}
+}

services/runner/runner.go

@@ -19,6 +19,11 @@ import (
 	log "github.com/sirupsen/logrus"
 )
 
+// Errprs
+var (
+	ErrBadProxyAPI = fmt.Errorf("proxy api must be specified as http(s) when scan api is websocket")
+)
+
 // Runner receives and starts the latest updater and supervisor.
 type Runner struct {
 	ctx          context.Context
@@ -112,6 +117,11 @@ func (runner *Runner) doStartUpCheck() error {
 	if err != nil {
 		return fmt.Errorf("scan api check failed: %v", err)
 	}
+
+	if err := CheckProxyAgainstScan(runner.cfg.Scan.JsonRpc.Url, runner.cfg.JsonRpcProxy.JsonRpc.Url); err != nil {
+		return err
+	}
+
 	if runner.cfg.Trace.Enabled {
 		// ensure that the trace json-rpc api is reachable
 		err = ethereum.TestAPI(runner.ctx, runner.fixTestRpcUrl(runner.cfg.Trace.JsonRpc.Url))