Add --storage.tsdb.retention.percentage (#10287)

Signed-off-by: Jérôme LOYET <822436+fatpat@users.noreply.github.com>

cmd/prometheus/main.go

@@ -415,6 +415,9 @@ func main() {
 	serverOnlyFlag(a, "storage.tsdb.retention.size", "Maximum number of bytes that can be stored for blocks. A unit is required, supported units: B, KB, MB, GB, TB, PB, EB. Ex: \"512MB\". Based on powers-of-2, so 1KB is 1024B.").
 		BytesVar(&cfg.tsdb.MaxBytes)
 
+	serverOnlyFlag(a, "storage.tsdb.retention.percentage", "Maximum percentage of the disk space that can be used to store blocks (prevails over storage.tsdb.retention.size).").
+		UintVar(&cfg.tsdb.MaxPercentage)
+
 	serverOnlyFlag(a, "storage.tsdb.no-lockfile", "Do not create lockfile in data directory.").
 		Default("false").BoolVar(&cfg.tsdb.NoLockfile)
 
@@ -635,9 +638,9 @@ func main() {
 	cfg.web.RoutePrefix = "/" + strings.Trim(cfg.web.RoutePrefix, "/")
 
 	if !agentMode {
-		if cfg.tsdb.RetentionDuration == 0 && cfg.tsdb.MaxBytes == 0 {
+		if cfg.tsdb.RetentionDuration == 0 && cfg.tsdb.MaxBytes == 0 && cfg.tsdb.MaxPercentage == 0 {
 			cfg.tsdb.RetentionDuration = defaultRetentionDuration
-			logger.Info("No time or size retention was set so using the default time retention", "duration", defaultRetentionDuration)
+			logger.Info("No time, size or percentage retention was set so using the default time retention", "duration", defaultRetentionDuration)
 		}
 
 		// Check for overflows. This limits our max retention to 100y.
@@ -650,6 +653,17 @@ func main() {
 			logger.Warn("Time retention value is too high. Limiting to: " + y.String())
 		}
 
+		if cfg.tsdb.MaxPercentage > 100 {
+			cfg.tsdb.MaxPercentage = 100
+			logger.Warn("Percentage retention value is too high. Limiting to: 100%")
+		}
+		if cfg.tsdb.MaxPercentage > 0 {
+			if prom_runtime.FsSize(localStoragePath) == 0 {
+				fmt.Fprintln(os.Stderr, fmt.Errorf("unable to detect size of partition %s, please disable retention percentage (%d%%)", localStoragePath, cfg.tsdb.MaxPercentage))
+				os.Exit(2)
+			}
+		}
+
 		// Max block size settings.
 		if cfg.tsdb.MaxBlockDuration == 0 {
 			maxBlockDuration, err := model.ParseDuration("31d")
@@ -824,6 +838,7 @@ func main() {
 	cfg.web.Context = ctxWeb
 	cfg.web.TSDBRetentionDuration = cfg.tsdb.RetentionDuration
 	cfg.web.TSDBMaxBytes = cfg.tsdb.MaxBytes
+	cfg.web.TSDBMaxPercentage = cfg.tsdb.MaxPercentage
 	cfg.web.TSDBDir = localStoragePath
 	cfg.web.LocalStorage = localStorage
 	cfg.web.Storage = fanoutStorage
@@ -1246,7 +1261,7 @@ func main() {
 					return fmt.Errorf("opening storage failed: %w", err)
 				}
 
-				switch fsType := prom_runtime.Statfs(localStoragePath); fsType {
+				switch fsType := prom_runtime.FsType(localStoragePath); fsType {
 				case "NFS_SUPER_MAGIC":
 					logger.Warn("This filesystem is not supported and may lead to data corruption and data loss. Please carefully read https://prometheus.io/docs/prometheus/latest/storage/ to learn more about supported filesystems.", "fs_type", fsType)
 				default:
@@ -1258,6 +1273,7 @@ func main() {
 					"MinBlockDuration", cfg.tsdb.MinBlockDuration,
 					"MaxBlockDuration", cfg.tsdb.MaxBlockDuration,
 					"MaxBytes", cfg.tsdb.MaxBytes,
+					"MaxPercentage", cfg.tsdb.MaxPercentage,
 					"NoLockfile", cfg.tsdb.NoLockfile,
 					"RetentionDuration", cfg.tsdb.RetentionDuration,
 					"WALSegmentSize", cfg.tsdb.WALSegmentSize,
@@ -1302,7 +1318,7 @@ func main() {
 					return fmt.Errorf("opening storage failed: %w", err)
 				}
 
-				switch fsType := prom_runtime.Statfs(localStoragePath); fsType {
+				switch fsType := prom_runtime.FsType(localStoragePath); fsType {
 				case "NFS_SUPER_MAGIC":
 					logger.Warn(fsType, "msg", "This filesystem is not supported and may lead to data corruption and data loss. Please carefully read https://prometheus.io/docs/prometheus/latest/storage/ to learn more about supported filesystems.")
 				default:
@@ -1782,6 +1798,7 @@ type tsdbOptions struct {
 	MaxBlockChunkSegmentSize       units.Base2Bytes
 	RetentionDuration              model.Duration
 	MaxBytes                       units.Base2Bytes
+	MaxPercentage                  uint
 	NoLockfile                     bool
 	WALCompression                 bool
 	WALCompressionType             string
@@ -1806,6 +1823,7 @@ func (opts tsdbOptions) ToTSDBOptions() tsdb.Options {
 		MaxBlockChunkSegmentSize:       int64(opts.MaxBlockChunkSegmentSize),
 		RetentionDuration:              int64(time.Duration(opts.RetentionDuration) / time.Millisecond),
 		MaxBytes:                       int64(opts.MaxBytes),
+		MaxPercentage:                  opts.MaxPercentage,
 		NoLockfile:                     opts.NoLockfile,
 		WALCompression:                 wlog.ParseCompressionType(opts.WALCompression, opts.WALCompressionType),
 		HeadChunksWriteQueueSize:       opts.HeadChunksWriteQueueSize,

docs/command-line/prometheus.md

@@ -37,6 +37,7 @@ The Prometheus monitoring server
 | <code class="text-nowrap">--storage.tsdb.path</code> | Base path for metrics storage. Use with server mode only. | `data/` |
 | <code class="text-nowrap">--storage.tsdb.retention.time</code> | How long to retain samples in storage. If neither this flag nor "storage.tsdb.retention.size" is set, the retention time defaults to 15d. Units Supported: y, w, d, h, m, s, ms. Use with server mode only. |  |
 | <code class="text-nowrap">--storage.tsdb.retention.size</code> | Maximum number of bytes that can be stored for blocks. A unit is required, supported units: B, KB, MB, GB, TB, PB, EB. Ex: "512MB". Based on powers-of-2, so 1KB is 1024B. Use with server mode only. |  |
+| <code class="text-nowrap">--storage.tsdb.retention.percentage</code> | Maximum percentage of the disk space that can be used to store blocks (prevails over storage.tsdb.retention.size). Use with server mode only. |  |
 | <code class="text-nowrap">--storage.tsdb.no-lockfile</code> | Do not create lockfile in data directory. Use with server mode only. | `false` |
 | <code class="text-nowrap">--storage.tsdb.head-chunks-write-queue-size</code> | Size of the queue through which head chunks are written to the disk to be m-mapped, 0 disables the queue completely. Experimental. Use with server mode only. | `0` |
 | <code class="text-nowrap">--storage.agent.path</code> | Base path for metrics storage. Use with agent mode only. | `data-agent/` |

tsdb/db.go

@@ -46,6 +46,7 @@ import (
 	_ "github.com/prometheus/prometheus/tsdb/goversion" // Load the package into main to make sure minimum Go version is met.
 	"github.com/prometheus/prometheus/tsdb/tsdbutil"
 	"github.com/prometheus/prometheus/tsdb/wlog"
+	prom_runtime "github.com/prometheus/prometheus/util/runtime"
 )
 
 const (
@@ -115,6 +116,11 @@ type Options struct {
 	// the current size of the database.
 	MaxBytes int64
 
+	// Maximum % of disk space to use for blocks to be retained
+	// 0 or less means disabled
+	// If both MaxBytes and MaxPercentage are set, percentage prevails
+	MaxPercentage uint
+
 	// NoLockfile disables creation and consideration of a lock file.
 	NoLockfile bool
 
@@ -1753,11 +1759,32 @@ func BeyondTimeRetention(db *DB, blocks []*Block) (deletable map[ulid.ULID]struc
 // BeyondSizeRetention returns those blocks which are beyond the size retention
 // set in the db options.
 func BeyondSizeRetention(db *DB, blocks []*Block) (deletable map[ulid.ULID]struct{}) {
-	// Size retention is disabled or no blocks to work with.
-	if len(blocks) == 0 || db.opts.MaxBytes <= 0 {
+	// No blocks to work with
+	if len(blocks) == 0 {
 		return
 	}
 
+	maxBytes := db.opts.MaxBytes
+
+	// percentage prevails
+	if db.opts.MaxPercentage > 0 {
+		// retrieve FS size
+		diskSize := prom_runtime.FsSize(db.dir)
+		if diskSize <= 0 {
+			db.logger.Warn("msg", "Unable to retrieve filesystem size of database directory (%s), skip percentage limitation and default to fixed size limitation", db.dir)
+		} else {
+			// apply percentage
+			maxBytes = int64(uint64(db.opts.MaxPercentage) * diskSize / 100)
+		}
+	}
+
+	// Size retention is disabled
+	if maxBytes <= 0 {
+		return
+	}
+	// update MaxBytes gauge
+	db.metrics.maxBytes.Set(float64(maxBytes))
+
 	deletable = make(map[ulid.ULID]struct{})
 
 	// Initializing size counter with WAL size and Head chunks
@@ -1765,7 +1792,7 @@ func BeyondSizeRetention(db *DB, blocks []*Block) (deletable map[ulid.ULID]struc
 	blocksSize := db.Head().Size()
 	for i, block := range blocks {
 		blocksSize += block.Size()
-		if blocksSize > db.opts.MaxBytes {
+		if blocksSize > maxBytes {
 			// Add this and all following blocks for deletion.
 			for _, b := range blocks[i:] {
 				deletable[b.meta.ULID] = struct{}{}

util/runtime/statfs.go

@@ -11,12 +11,18 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build openbsd || windows || netbsd || solaris
+//go:build openbsd || netbsd || solaris
 
 package runtime
 
-// Statfs returns the file system type (Unix only)
+// FsType returns the file system type (Unix only)
 // syscall.Statfs_t isn't available on openbsd
-func Statfs(path string) string {
+func FsType(path string) string {
 	return "unknown"
 }
+
+// FsSize returns the file system size (Unix only)
+// syscall.Statfs_t isn't available on openbsd
+func FsSize(path string) uint64 {
+	return 0
+}

util/runtime/statfs_default.go

@@ -20,8 +20,8 @@ import (
 	"syscall"
 )
 
-// Statfs returns the file system type (Unix only).
-func Statfs(path string) string {
+// FsType returns the file system type (Unix only).
+func FsType(path string) string {
 	// Types of file systems that may be returned by `statfs`
 	fsTypes := map[int64]string{
 		0xadf5:     "ADFS_SUPER_MAGIC",
@@ -67,6 +67,7 @@ func Statfs(path string) string {
 		0x012FF7B4: "XENIX_SUPER_MAGIC",
 		0x58465342: "XFS_SUPER_MAGIC",
 		0x012FD16D: "_XIAFS_SUPER_MAGIC",
+		0x794c7630: "OVERLAYFS_SUPER_MAGIC",
 	}
 
 	var fs syscall.Statfs_t
@@ -82,3 +83,13 @@ func Statfs(path string) string {
 	}
 	return strconv.FormatInt(localType, 16)
 }
+
+// FsSize returns the file system size (Unix only).
+func FsSize(path string) uint64 {
+	var fs syscall.Statfs_t
+	err := syscall.Statfs(path, &fs)
+	if err != nil {
+		return 0
+	}
+	return uint64(fs.Bsize) * fs.Blocks
+}

util/runtime/statfs_linux_386.go

@@ -20,8 +20,8 @@ import (
 	"syscall"
 )
 
-// Statfs returns the file system type (Unix only)
-func Statfs(path string) string {
+// FsType returns the file system type (Unix only)
+func FsType(path string) string {
 	// Types of file systems that may be returned by `statfs`
 	fsTypes := map[int32]string{
 		0xadf5:     "ADFS_SUPER_MAGIC",
@@ -63,6 +63,7 @@ func Statfs(path string) string {
 		0x012FF7B4: "XENIX_SUPER_MAGIC",
 		0x58465342: "XFS_SUPER_MAGIC",
 		0x012FD16D: "_XIAFS_SUPER_MAGIC",
+		0x794c7630: "OVERLAYFS_SUPER_MAGIC",
 	}
 
 	var fs syscall.Statfs_t
@@ -75,3 +76,13 @@ func Statfs(path string) string {
 	}
 	return strconv.Itoa(int(fs.Type))
 }
+
+// FsSize returns the file system size (Unix only)
+func FsSize(path string) uint64 {
+	var fs syscall.Statfs_t
+	err := syscall.Statfs(path, &fs)
+	if err != nil {
+		return 0
+	}
+	return uint64(fs.Bsize) * fs.Blocks
+}

util/runtime/statfs_uint32.go

@@ -20,8 +20,8 @@ import (
 	"syscall"
 )
 
-// Statfs returns the file system type (Unix only)
-func Statfs(path string) string {
+// FsType returns the file system type (Unix only)
+func FsType(path string) string {
 	// Types of file systems that may be returned by `statfs`
 	fsTypes := map[uint32]string{
 		0xadf5:     "ADFS_SUPER_MAGIC",
@@ -63,6 +63,7 @@ func Statfs(path string) string {
 		0x012FF7B4: "XENIX_SUPER_MAGIC",
 		0x58465342: "XFS_SUPER_MAGIC",
 		0x012FD16D: "_XIAFS_SUPER_MAGIC",
+		0x794c7630: "OVERLAYFS_SUPER_MAGIC",
 	}
 
 	var fs syscall.Statfs_t
@@ -75,3 +76,13 @@ func Statfs(path string) string {
 	}
 	return strconv.Itoa(int(fs.Type))
 }
+
+// FsSize returns the file system size (Unix only)
+func FsSize(path string) uint64 {
+	var fs syscall.Statfs_t
+	err := syscall.Statfs(path, &fs)
+	if err != nil {
+		return 0
+	}
+	return uint64(fs.Bsize) * fs.Blocks
+}

util/runtime/statfs_unix_test.go

@@ -0,0 +1,59 @@
+// Copyright 2016 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build !windows && !openbsd && !netbsd && !solaris
+// +build !windows,!openbsd,!netbsd,!solaris
+
+package runtime
+
+import (
+	"os"
+	"testing"
+
+	"github.com/grafana/regexp"
+	"github.com/stretchr/testify/require"
+)
+
+var regexpFsType = regexp.MustCompile("^[A-Z][A-Z0-9_]*_MAGIC$")
+
+func TestFsType(t *testing.T) {
+	var fsType string
+
+	path, err := os.Getwd()
+	require.NoError(t, err)
+
+	fsType = FsType(path)
+	require.Regexp(t, regexpFsType, fsType)
+
+	fsType = FsType("/no/where/to/be/found")
+	require.Equal(t, "0", fsType)
+
+	fsType = FsType("  %% not event a real path\n\n")
+	require.Equal(t, "0", fsType)
+}
+
+func TestFsSize(t *testing.T) {
+	var size uint64
+
+	path, err := os.Getwd()
+	require.NoError(t, err)
+
+	size = FsSize(path)
+	require.Positive(t, size)
+
+	size = FsSize("/no/where/to/be/found")
+	require.Equal(t, uint64(0), size)
+
+	size = FsSize("  %% not event a real path\n\n")
+	require.Equal(t, uint64(0), size)
+}

util/runtime/statfs_windows.go

@@ -0,0 +1,61 @@
+// Copyright 2017 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build windows
+// +build windows
+
+package runtime
+
+import (
+	"os"
+	"syscall"
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+var (
+	dll                 = windows.MustLoadDLL("kernel32.dll")
+	getDiskFreeSpaceExW = dll.MustFindProc("GetDiskFreeSpaceExW")
+)
+
+// FsType returns the file system type (Unix only)
+// syscall.Statfs_t isn't available on openbsd
+func FsType(path string) string {
+	return "unknown"
+}
+
+// FsSize returns the file system size (Unix only)
+// syscall.Statfs_t isn't available on openbsd
+func FsSize(path string) uint64 {
+	// ensure the path exists
+	if _, err := os.Stat(path); err != nil {
+		return 0
+	}
+
+	var avail int64
+	var total int64
+	var free int64
+	// https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-getdiskfreespaceexa
+	ret, _, _ := getDiskFreeSpaceExW.Call(
+		uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(path))),
+		uintptr(unsafe.Pointer(&avail)),
+		uintptr(unsafe.Pointer(&total)),
+		uintptr(unsafe.Pointer(&free)))
+
+	if ret == 0 || uint64(free) > uint64(total) {
+		return 0
+	}
+
+	return uint64(total)
+}

util/runtime/statfs_windows_test.go

@@ -0,0 +1,50 @@
+// Copyright 2016 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build windows
+// +build windows
+
+package runtime
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestFsType(t *testing.T) {
+	var fsType string
+
+	path, err := os.Getwd()
+	require.NoError(t, err)
+
+	fsType = FsType(path)
+	require.Equal(t, "unknown", fsType)
+
+	fsType = FsType("A:\\no\\where\\to\\be\\found")
+	require.Equal(t, "unknown", fsType)
+}
+
+func TestFsSize(t *testing.T) {
+	var size uint64
+
+	size = FsSize("C:\\")
+	require.Positive(t, size)
+
+	size = FsSize("c:\\no\\where\\to\\be\\found")
+	require.Equal(t, uint64(0), size)
+
+	size = FsSize("  %% not event a real path\n\n")
+	require.Equal(t, uint64(0), size)
+}

web/web.go

@@ -257,6 +257,7 @@ type Options struct {
 	TSDBRetentionDuration model.Duration
 	TSDBDir               string
 	TSDBMaxBytes          units.Base2Bytes
+	TSDBMaxPercentage     uint
 	LocalStorage          LocalStorage
 	Storage               storage.Storage
 	ExemplarStorage       storage.ExemplarQueryable
@@ -813,6 +814,12 @@ func (h *Handler) runtimeInfo() (api_v1.RuntimeInfo, error) {
 		}
 		status.StorageRetention += h.options.TSDBMaxBytes.String()
 	}
+	if h.options.TSDBMaxPercentage != 0 {
+		if status.StorageRetention != "" {
+			status.StorageRetention += " or "
+		}
+		status.StorageRetention = status.StorageRetention + strconv.FormatUint(uint64(h.options.TSDBMaxPercentage), 10) + "%"
+	}
 
 	metrics, err := h.gatherer.Gather()
 	if err != nil {