parquet_pushdown(M0-C5): add weed pushdown.ping smoke command

Add weed/command/pushdown_ping.go that dials a pushdown daemon over
gRPC, calls Ping with a 5s timeout, and prints the daemon's reported
version and trust mode. Used both as a deployment smoke test and by
the M0 integration test.

Default -server=localhost:18888 matches the daemon's default listen
port. -tls toggles between insecure and the security/grpc.client
TLS config; default insecure mirrors the iam command's pattern for
local-development smoke tests.

Naming follows the existing dotted convention (mq.agent, mq.broker,
mq.kafka.gateway): the daemon is "weed pushdown", the smoke test is
"weed pushdown.ping".

weed/command/command.go

@@ -38,6 +38,7 @@ var Commands = []*Command{
 	cmdMqBroker,
 	cmdMqKafkaGateway,
 	cmdPushdown,
+	cmdPushdownPing,
 	cmdS3,
 	cmdScaffold,
 	cmdServer,

weed/command/pushdown_ping.go

@@ -0,0 +1,71 @@
+package command
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"time"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+
+	"github.com/seaweedfs/seaweedfs/weed/glog"
+	pb "github.com/seaweedfs/seaweedfs/weed/pb/parquet_pushdown_pb"
+	"github.com/seaweedfs/seaweedfs/weed/security"
+	"github.com/seaweedfs/seaweedfs/weed/util"
+)
+
+var (
+	pushdownPingOptions PushdownPingOptions
+)
+
+type PushdownPingOptions struct {
+	target  *string
+	timeout *time.Duration
+	useTLS  *bool
+}
+
+func init() {
+	cmdPushdownPing.Run = runPushdownPing
+	pushdownPingOptions.target = cmdPushdownPing.Flag.String("server", "localhost:18888", "pushdown daemon gRPC address")
+	pushdownPingOptions.timeout = cmdPushdownPing.Flag.Duration("timeout", 5*time.Second, "RPC deadline")
+	pushdownPingOptions.useTLS = cmdPushdownPing.Flag.Bool("tls", false, "dial with TLS using grpc.client config")
+}
+
+var cmdPushdownPing = &Command{
+	UsageLine: "pushdown.ping [-server=<ip:port>]",
+	Short:     "<WIP> ping a running pushdown daemon (M0 smoke test)",
+	Long: `ping a running pushdown daemon.
+
+	Calls the SeaweedParquetPushdown.Ping RPC and prints the daemon's
+	reported version and trust mode. Used as a deployment smoke test
+	and by the M0 integration test.`,
+}
+
+func runPushdownPing(cmd *Command, args []string) bool {
+	util.LoadSecurityConfiguration()
+
+	dialOpt := grpc.WithTransportCredentials(insecure.NewCredentials())
+	if *pushdownPingOptions.useTLS {
+		dialOpt = security.LoadClientTLS(util.GetViper(), "grpc.client")
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), *pushdownPingOptions.timeout)
+	defer cancel()
+
+	conn, err := grpc.NewClient(*pushdownPingOptions.target, dialOpt)
+	if err != nil {
+		glog.Errorf("dial %s: %v", *pushdownPingOptions.target, err)
+		return false
+	}
+	defer conn.Close()
+
+	resp, err := pb.NewSeaweedParquetPushdownClient(conn).Ping(ctx, &pb.PingRequest{})
+	if err != nil {
+		glog.Errorf("ping %s: %v", *pushdownPingOptions.target, err)
+		return false
+	}
+
+	fmt.Fprintf(os.Stdout, "ok: server=%s version=%q trust=%q\n", *pushdownPingOptions.target, resp.Version, resp.TrustMode)
+	return true
+}