Preserve bare gRPC logging flag compatibility

README.md

@@ -54,9 +54,10 @@ Flags:
                                    also accepted
       --param-file=STRING          YAML or JSON file of query parameters (name
                                    to type/literal string)
-      --log-grpc="off"             gRPC logging mode: off, metadata, or payload
-                                   (payload may include request and response
-                                   payloads in logs)
+      --log-grpc                   gRPC logging: --log-grpc means payload;
+                                   use --log-grpc=off|metadata|payload to select
+                                   a mode (payload may include request and
+                                   response payloads)
       --experimental-trace-project=STRING
                                    Export traces to Cloud Trace in the given
                                    project.
@@ -327,6 +328,9 @@ $ execspansql $DATABASE_ID --query-mode=PROFILE --sql 'SELECT 1' --experimental-
 ```
 
 Note: `--experimental-trace-stdout` writes to **stderr**, not stdout.
+
+A bare `--log-grpc` retains its previous meaning: payload logging. Logging is off when the flag is omitted. Use `--log-grpc=off`, `--log-grpc=metadata`, or `--log-grpc=payload` to select a mode; an explicit value must use `=` so the next database argument is not consumed. Legacy boolean values such as `--log-grpc=true` and `--log-grpc=false` remain accepted.
+
 Note: `--log-grpc=payload` can log request and response payloads (including bound parameters and row values) and should only be used in trusted environments.
 
 ![trace.png](docs/trace.png)

log_grpc_flag.go

@@ -0,0 +1,35 @@
+package main
+
+import (
+	"strings"
+
+	"github.com/alecthomas/kong"
+)
+
+// logGrpcFlag retains the old boolean flag syntax while accepting explicit
+// logging modes. As with boolean flags, explicit values use "=" so a bare
+// flag never consumes the following database argument.
+type logGrpcFlag string
+
+func (*logGrpcFlag) IsBool() bool { return true }
+
+func (m *logGrpcFlag) Decode(ctx *kong.DecodeContext) error {
+	if ctx.Scan.Peek().Type != kong.FlagValueToken {
+		*m = logGrpcModePayload
+		return nil
+	}
+	var value string
+	if err := ctx.Scan.PopValueInto("logging mode", &value); err != nil {
+		return err
+	}
+	// Preserve Kong's previous boolean spellings as well as the bare flag.
+	// The enum tag validates explicit mode names after this normalization.
+	switch strings.ToLower(value) {
+	case "true", "1", "yes":
+		value = logGrpcModePayload
+	case "false", "0", "no":
+		value = logGrpcModeOff
+	}
+	*m = logGrpcFlag(value)
+	return nil
+}

log_grpc_flag_test.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/alecthomas/kong"
+)
+
+func TestLogGrpcFlag(t *testing.T) {
+	for _, tt := range []struct {
+		name    string
+		args    []string
+		want    string
+		wantDB  string
+		wantErr bool
+	}{
+		{name: "omitted", args: []string{"db"}, want: "off", wantDB: "db"},
+		{name: "bare_before_database", args: []string{"--log-grpc", "db"}, want: "payload", wantDB: "db"},
+		{name: "bare_after_database", args: []string{"db", "--log-grpc"}, want: "payload", wantDB: "db"},
+		{name: "mode_named_database", args: []string{"--log-grpc", "metadata"}, want: "payload", wantDB: "metadata"},
+		{name: "off", args: []string{"db", "--log-grpc=off"}, want: "off", wantDB: "db"},
+		{name: "metadata", args: []string{"db", "--log-grpc=metadata"}, want: "metadata", wantDB: "db"},
+		{name: "payload", args: []string{"db", "--log-grpc=payload"}, want: "payload", wantDB: "db"},
+		{name: "legacy_true", args: []string{"db", "--log-grpc=true"}, want: "payload", wantDB: "db"},
+		{name: "legacy_yes", args: []string{"db", "--log-grpc=YES"}, want: "payload", wantDB: "db"},
+		{name: "legacy_one", args: []string{"db", "--log-grpc=1"}, want: "payload", wantDB: "db"},
+		{name: "legacy_false", args: []string{"db", "--log-grpc=false"}, want: "off", wantDB: "db"},
+		{name: "legacy_no", args: []string{"db", "--log-grpc=NO"}, want: "off", wantDB: "db"},
+		{name: "legacy_zero", args: []string{"db", "--log-grpc=0"}, want: "off", wantDB: "db"},
+		{name: "invalid", args: []string{"db", "--log-grpc=invalid"}, wantErr: true},
+		{name: "empty", args: []string{"db", "--log-grpc="}, wantErr: true},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			var o opts
+			parser, err := kong.New(&o)
+			if err != nil {
+				t.Fatal(err)
+			}
+			args := append(append([]string{}, tt.args...), "--project=p", "--instance=i", "--sql=SELECT 1")
+			_, err = parser.Parse(args)
+			if tt.wantErr {
+				if err == nil || !strings.Contains(err.Error(), "--log-grpc") {
+					t.Fatalf("error = %v, want invalid log mode", err)
+				}
+				return
+			}
+			if err != nil {
+				t.Fatal(err)
+			}
+			if string(o.LogGrpc) != tt.want || o.Database != tt.wantDB {
+				t.Fatalf("mode=%q database=%q, want %q %q", o.LogGrpc, o.Database, tt.want, tt.wantDB)
+			}
+		})
+	}
+}

main.go

@@ -65,7 +65,7 @@ type opts struct {
 	JqInputMode          string        `name:"jq-input-mode" enum:"eager,lazy" default:"eager" help:"How query rows are passed to jq (json/yaml only): eager (full ResultSet), lazy (JQValue root)."`
 	ParamFlags           []string      `name:"param" help:"[name]=[type or literal]; legacy [name]:[...] also accepted"`
 	ParamFile            string        `name:"param-file" help:"YAML or JSON file of query parameters (name to type/literal string)"`
-	LogGrpc              string        `name:"log-grpc" enum:"off,metadata,payload" default:"off" help:"gRPC logging mode: off, metadata, or payload (payload may include request and response payloads in logs)"`
+	LogGrpc              logGrpcFlag   `name:"log-grpc" enum:"off,metadata,payload" default:"off" help:"gRPC logging: --log-grpc means payload; use --log-grpc=off|metadata|payload to select a mode (payload may include request and response payloads)"`
 	TraceProject         string        `name:"experimental-trace-project" xor:"trace" help:"Export traces to Cloud Trace in the given project."`
 	TraceStdout          bool          `name:"experimental-trace-stdout" xor:"trace" help:"Export spans to stderr as pretty JSON (local debugging)."`
 	TraceOTLP            bool          `name:"experimental-trace-otlp" xor:"trace" help:"Export spans via OTLP/gRPC to a local OpenTelemetry collector."`
@@ -474,7 +474,7 @@ func runCLI(clientOptions ...option.ClientOption) error {
 		}()
 	}
 
-	client, err := newClient(ctx, o.Project, o.Instance, o.Database, o.DatabaseRole, o.LogGrpc, tracingEnabled(o), clientOptions...)
+	client, err := newClient(ctx, o.Project, o.Instance, o.Database, o.DatabaseRole, string(o.LogGrpc), tracingEnabled(o), clientOptions...)
 	if err != nil {
 		return err
 	}