Add fmt-gen subcommand (minio#20192)

fmt-gen subcommand is only available when built with build tag `fmtgen`.

cmd/fmt-gen.go

@@ -0,0 +1,120 @@
+// Copyright (c) 2015-2024 MinIO, Inc.
+//
+// This file is part of MinIO Object Storage stack
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+//go:build fmtgen
+
+package cmd
+
+import (
+	"encoding/json"
+	"log"
+	"os"
+	"path/filepath"
+
+	"github.com/klauspost/compress/zip"
+	"github.com/minio/cli"
+)
+
+var fmtGenFlags = []cli.Flag{
+	cli.IntFlag{
+		Name:  "parity",
+		Usage: "specify erasure code parity",
+	},
+	cli.StringFlag{
+		Name:  "deployment-id",
+		Usage: "deployment-id of the MinIO cluster for which format.json is needed",
+	},
+	cli.StringFlag{
+		Name:   "address",
+		Value:  ":" + GlobalMinioDefaultPort,
+		Usage:  "bind to a specific ADDRESS:PORT, ADDRESS can be an IP or hostname",
+		EnvVar: "MINIO_ADDRESS",
+	},
+}
+
+var fmtGenCmd = cli.Command{
+	Name:   "fmt-gen",
+	Usage:  "Generate format.json files for an erasure server pool",
+	Flags:  append(fmtGenFlags, GlobalFlags...),
+	Action: fmtGenMain,
+	CustomHelpTemplate: `NAME:
+  {{.HelpName}} - {{.Usage}}
+
+USAGE:
+  {{.HelpName}} {{if .VisibleFlags}}[FLAGS] {{end}}DIR1 [DIR2..]
+  {{.HelpName}} {{if .VisibleFlags}}[FLAGS] {{end}}DIR{1...64}
+  {{.HelpName}} {{if .VisibleFlags}}[FLAGS] {{end}}DIR{1...64} DIR{65...128}
+
+DIR:
+  DIR points to a directory on a filesystem. When you want to combine
+  multiple drives into a single large system, pass one directory per
+  filesystem separated by space. You may also use a '...' convention
+  to abbreviate the directory arguments. Remote directories in a
+  distributed setup are encoded as HTTP(s) URIs.
+{{if .VisibleFlags}}
+FLAGS:
+  {{range .VisibleFlags}}{{.}}
+  {{end}}{{end}}
+EXAMPLES:
+  1. Generate format.json.zip containing format.json files for all drives in a distributed MinIO server pool of 32 nodes with 32 drives each.
+     {{.Prompt}} {{.HelpName}} http://node{1...32}.example.com/mnt/export{1...32}
+
+`,
+}
+
+func fmtGenMain(ctxt *cli.Context) {
+	deploymentID := ctxt.String("deployment-id")
+	err := buildServerCtxt(ctxt, &globalServerCtxt)
+	if err != nil {
+		log.Fatalln(err)
+	}
+	handleCommonArgs(globalServerCtxt)
+	pools, _, err := createServerEndpoints(globalMinioAddr, globalServerCtxt.Layout.pools, globalServerCtxt.Layout.legacy)
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	zipFile, err := os.Create("format.json.zip")
+	if err != nil {
+		log.Fatalf("failed to create format.json.zip: %v", err)
+	}
+	defer zipFile.Close()
+	fmtZipW := zip.NewWriter(zipFile)
+	defer fmtZipW.Close()
+	for _, pool := range pools { // for each pool
+		setCount, setDriveCount := pool.SetCount, pool.DrivesPerSet
+		format := newFormatErasureV3(setCount, setDriveCount)
+		format.ID = deploymentID
+		for i := 0; i < setCount; i++ { // for each erasure set
+			for j := 0; j < setDriveCount; j++ {
+				newFormat := format.Clone()
+				newFormat.Erasure.This = format.Erasure.Sets[i][j]
+				if deploymentID != "" {
+					newFormat.ID = deploymentID
+				}
+				drive := pool.Endpoints[i*setDriveCount+j]
+				fmtBytes, err := json.Marshal(newFormat)
+				if err != nil {
+					//nolint:gocritic
+					log.Fatalf("failed to marshal format.json for %s: %v", drive.String(), err)
+				}
+				fmtJSON := filepath.Join(drive.Host, drive.Path, minioMetaBucket, "format.json")
+				embedFileInZip(fmtZipW, fmtJSON, fmtBytes, 0o600)
+			}
+		}
+	}
+}

cmd/fmt-gen_notsupported.go

@@ -0,0 +1,24 @@
+// Copyright (c) 2015-2024 MinIO, Inc.
+//
+// # This file is part of MinIO Object Storage stack
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+//go:build !fmtgen
+
+package cmd
+
+import "github.com/minio/cli"
+
+var fmtGenCmd cli.Command

cmd/main.go

@@ -107,6 +107,11 @@ func newApp(name string) *cli.App {
 
 	// registerCommand registers a cli command.
 	registerCommand := func(command cli.Command) {
+		// avoid registering commands which are not being built (via
+		// go:build tags)
+		if command.Name == "" {
+			return
+		}
 		commands = append(commands, command)
 		commandsTree.Insert(command.Name)
 	}
@@ -134,6 +139,7 @@ func newApp(name string) *cli.App {
 
 	// Register all commands.
 	registerCommand(serverCmd)
+	registerCommand(fmtGenCmd)
 
 	// Set up app.
 	cli.HelpFlag = cli.BoolFlag{