add --metadata to add user metadata during put

cli/flags.go

@@ -269,6 +269,10 @@ var ioFlags = []cli.Flag{
 		Value: 0,
 		Usage: "Rate limit each instance to this number of requests per second (0 to disable)",
 	},
+	cli.StringSliceFlag{
+		Name:  "metadata",
+		Usage: "Set user metada to all objects using the format <key>=<value>. Random value can be set with `rand:%length`. Can be used multiple times. Example: --metadata foo=bar --metadata randomValue=rand:1024.",
+	},
 }
 
 func getCommon(ctx *cli.Context, src func() generator.Source) bench.Common {

cli/put.go

@@ -18,6 +18,9 @@
 package cli
 
 import (
+	"fmt"
+	"math/rand"
+	"strings"
 	"github.com/minio/cli"
 	"github.com/minio/minio-go/v7"
 	"github.com/minio/pkg/v2/console"
@@ -71,16 +74,43 @@ func mainPut(ctx *cli.Context) error {
 	return runBench(ctx, &b)
 }
 
+const metadataChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890-_."
+
 // putOpts retrieves put options from the context.
 func putOpts(ctx *cli.Context) minio.PutObjectOptions {
 	pSize, _ := toSize(ctx.String("part.size"))
+
+	/* metadatas */
+	metadatas := make(map[string]string)
+	for _, v := range ctx.StringSlice("metadata") {
+			idx := strings.Index(v, "=")
+			if idx <= 0 {
+				console.Fatal("--metadata takes `key=value` argument")
+			}
+			key := v[:idx]
+			value := v[idx+1:]
+			if len(value) == 0 {
+				console.Fatal("--metadata value can't be empty")
+			}
+			var rand_n int;
+			if _, err := fmt.Sscanf(value, "rand:%d", &rand_n); err == nil {
+				rng := rand.New(rand.NewSource(int64(rand.Uint64())))
+				value = ""
+				for i:=0; i<rand_n; i++ {
+					value = value + string(metadataChars[rng.Int()%len(metadataChars)])
+				}
+			}
+			metadatas[key] = value
+	}
+
 	return minio.PutObjectOptions{
 		ServerSideEncryption: newSSE(ctx),
 		DisableMultipart:     ctx.Bool("disable-multipart"),
 		DisableContentSha256: ctx.Bool("disable-sha256-payload"),
 		SendContentMd5:       ctx.Bool("md5"),
 		StorageClass:         ctx.String("storage-class"),
 		PartSize:             pSize,
+		UserMetadata:         metadatas,
 	}
 }