config: add freeBytes gc policy entry

Signed-off-by: Justin Chadwell <me@jedevc.com>

api/services/control/control.proto

@@ -32,6 +32,7 @@ message PruneRequest {
 	bool all = 2;
 	int64 keepDuration = 3 [(gogoproto.nullable) = true];
 	int64 keepBytes = 4 [(gogoproto.nullable) = true];
+	int64 freeBytes = 5 [(gogoproto.nullable) = true];
 }
 
 message DiskUsageRequest {

api/types/worker.proto

@@ -22,6 +22,7 @@ message GCPolicy {
 	int64 keepDuration = 2;
 	int64 keepBytes = 3;
 	repeated string filters = 4;
+	int64 freeBytes = 5;
 }
 
 message BuildkitVersion {

cache/manager.go

@@ -22,6 +22,7 @@ import (
 	"github.com/moby/buildkit/session"
 	"github.com/moby/buildkit/snapshot"
 	"github.com/moby/buildkit/util/bklog"
+	"github.com/moby/buildkit/util/disk"
 	"github.com/moby/buildkit/util/flightcontrol"
 	"github.com/moby/buildkit/util/progress"
 	digest "github.com/opencontainers/go-digest"
@@ -1053,26 +1054,46 @@ func (cm *cacheManager) pruneOnce(ctx context.Context, ch chan client.UsageInfo,
 		}
 	}
 
+	// TODO: pick a better path here
+	totalFree, _, err := disk.GetDiskSize(cm.mountPool.tmpdirRoot)
+	if err != nil {
+		return err
+	}
+
 	return cm.prune(ctx, ch, pruneOpt{
-		filter:       filter,
-		all:          opt.All,
-		checkShared:  check,
-		keepDuration: opt.KeepDuration,
-		keepBytes:    opt.KeepBytes,
-		totalSize:    totalSize,
+		filter:         filter,
+		all:            opt.All,
+		checkShared:    check,
+		keepDuration:   opt.KeepDuration,
+		keepBytes:      opt.KeepBytes,
+		totalKeptBytes: totalSize,
+		freeBytes:      opt.FreeBytes,
+		totalFreeBytes: totalFree,
 	})
 }
 
 func (cm *cacheManager) prune(ctx context.Context, ch chan client.UsageInfo, opt pruneOpt) (err error) {
-	var toDelete []*deleteRecord
-
-	if opt.keepBytes != 0 && opt.totalSize < opt.keepBytes {
+	var gcMode, gcNeeded bool
+	if opt.keepBytes != 0 {
+		gcMode = true
+		if opt.totalKeptBytes >= opt.keepBytes {
+			gcNeeded = true
+		}
+	}
+	if opt.freeBytes != 0 {
+		gcMode = true
+		if opt.totalFreeBytes >= opt.freeBytes {
+			gcNeeded = true
+		}
+	}
+	if gcMode && !gcNeeded {
 		return nil
 	}
 
+	var toDelete []*deleteRecord
+
 	cm.mu.Lock()
 
-	gcMode := opt.keepBytes != 0
 	cutOff := time.Now().Add(-opt.keepDuration)
 
 	locked := map[*sync.Mutex]struct{}{}
@@ -1240,7 +1261,7 @@ func (cm *cacheManager) prune(ctx context.Context, ch chan client.UsageInfo, opt
 			c.Size = cr.equalImmutable.getSize() // benefit from DiskUsage calc
 		}
 
-		opt.totalSize -= c.Size
+		opt.totalKeptBytes -= c.Size
 
 		if cr.equalImmutable != nil {
 			if err1 := cr.equalImmutable.remove(ctx, false); err == nil {
@@ -1606,12 +1627,15 @@ func adaptUsageInfo(info *client.UsageInfo) filters.Adaptor {
 }
 
 type pruneOpt struct {
-	filter       filters.Filter
-	all          bool
-	checkShared  ExternalRefChecker
-	keepDuration time.Duration
-	keepBytes    int64
-	totalSize    int64
+	filter      filters.Filter
+	all         bool
+	checkShared ExternalRefChecker
+
+	keepDuration   time.Duration
+	keepBytes      int64
+	totalKeptBytes int64
+	freeBytes      int64
+	totalFreeBytes int64
 }
 
 type deleteRecord struct {

client/prune.go

@@ -19,6 +19,7 @@ func (c *Client) Prune(ctx context.Context, ch chan UsageInfo, opts ...PruneOpti
 		Filter:       info.Filter,
 		KeepDuration: int64(info.KeepDuration),
 		KeepBytes:    int64(info.KeepBytes),
+		FreeBytes:    int64(info.FreeBytes),
 	}
 	if info.All {
 		req.All = true
@@ -63,6 +64,7 @@ type PruneInfo struct {
 	All          bool          `json:"all"`
 	KeepDuration time.Duration `json:"keepDuration"`
 	KeepBytes    int64         `json:"keepBytes"`
+	FreeBytes    int64         `json:"freeBytes"`
 }
 
 type pruneOptionFunc func(*PruneInfo)
@@ -75,9 +77,10 @@ var PruneAll = pruneOptionFunc(func(pi *PruneInfo) {
 	pi.All = true
 })
 
-func WithKeepOpt(duration time.Duration, bytes int64) PruneOption {
+func WithKeepOpt(duration time.Duration, bytes int64, freeBytes int64) PruneOption {
 	return pruneOptionFunc(func(pi *PruneInfo) {
 		pi.KeepDuration = duration
 		pi.KeepBytes = bytes
+		pi.FreeBytes = freeBytes
 	})
 }

client/workers.go

@@ -66,6 +66,7 @@ func fromAPIGCPolicy(in []*apitypes.GCPolicy) []PruneInfo {
 			Filter:       p.Filters,
 			KeepDuration: time.Duration(p.KeepDuration),
 			KeepBytes:    p.KeepBytes,
+			FreeBytes:    p.FreeBytes,
 		})
 	}
 	return out

cmd/buildctl/debug/workers.go

@@ -94,6 +94,9 @@ func printWorkersVerbose(tw *tabwriter.Writer, winfo []*client.WorkerInfo) {
 			if rule.KeepBytes > 0 {
 				fmt.Fprintf(tw, "\tKeep Bytes:\t%g\n", units.Bytes(rule.KeepBytes))
 			}
+			if rule.FreeBytes > 0 {
+				fmt.Fprintf(tw, "\tFree Bytes:\t%g\n", units.Bytes(rule.FreeBytes))
+			}
 		}
 		fmt.Fprintf(tw, "\n")
 	}

cmd/buildctl/prune.go

@@ -25,6 +25,10 @@ var pruneCommand = cli.Command{
 			Name:  "keep-storage",
 			Usage: "Keep data below this limit (in MB)",
 		},
+		cli.Float64Flag{
+			Name:  "free-storage",
+			Usage: "Keep free data below this limit (in MB)",
+		},
 		cli.StringSliceFlag{
 			Name:  "filter, f",
 			Usage: "Filter records",
@@ -56,7 +60,11 @@ func prune(clicontext *cli.Context) error {
 
 	opts := []client.PruneOption{
 		client.WithFilter(clicontext.StringSlice("filter")),
-		client.WithKeepOpt(clicontext.Duration("keep-duration"), int64(clicontext.Float64("keep-storage")*1e6)),
+		client.WithKeepOpt(
+			clicontext.Duration("keep-duration"),
+			int64(clicontext.Float64("keep-storage")*1e6),
+			int64(clicontext.Float64("free-storage")*1e6),
+		),
 	}
 
 	if clicontext.Bool("all") {

cmd/buildkitd/config/config.go

@@ -157,6 +157,7 @@ type GCPolicy struct {
 	All          bool      `toml:"all"`
 	KeepBytes    DiskSpace `toml:"keepBytes"`
 	KeepDuration Duration  `toml:"keepDuration"`
+	FreeBytes    DiskSpace `toml:"freeBytes"`
 	Filters      []string  `toml:"filters"`
 }
 

cmd/buildkitd/config/gcpolicy.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/docker/go-units"
 	"github.com/moby/buildkit/util/bklog"
+	"github.com/moby/buildkit/util/disk"
 	"github.com/pkg/errors"
 )
 
@@ -118,7 +119,7 @@ func (d DiskSpace) AsBytes(root string) int64 {
 		return 0
 	}
 
-	diskSize, err := getDiskSize(root)
+	_, diskSize, err := disk.GetDiskSize(root)
 	if err != nil {
 		bklog.L.Warnf("failed to get disk size: %v", err)
 		return defaultCap

cmd/buildkitd/config/gcpolicy_unix.go

@@ -1,19 +1,3 @@
-//go:build !windows && !openbsd
-// +build !windows,!openbsd
-
 package config
 
-import (
-	"syscall"
-)
-
 var DiskSpacePercentage int64 = 10
-
-func getDiskSize(root string) (int64, error) {
-	var st syscall.Statfs_t
-	if err := syscall.Statfs(root, &st); err != nil {
-		return 0, err
-	}
-	diskSize := int64(st.Bsize) * int64(st.Blocks)
-	return diskSize, nil
-}

cmd/buildkitd/config/gcpolicy_windows.go

@@ -1,31 +1,5 @@
-//go:build windows
-// +build windows
-
 package config
 
-import (
-	"golang.org/x/sys/windows"
-)
-
 // set as double that for Linux since
 // Windows images are generally larger.
 var DiskSpacePercentage int64 = 20
-
-func getDiskSize(root string) (int64, error) {
-	rootUTF16, err := windows.UTF16FromString(root)
-	if err != nil {
-		return 0, err
-	}
-	var freeAvailableBytes uint64
-	var totalBytes uint64
-	var totalFreeBytes uint64
-
-	if err := windows.GetDiskFreeSpaceEx(
-		&rootUTF16[0],
-		&freeAvailableBytes,
-		&totalBytes,
-		&totalFreeBytes); err != nil {
-		return 0, err
-	}
-	return int64(totalBytes), nil
-}

cmd/buildkitd/main.go

@@ -928,6 +928,7 @@ func getGCPolicy(cfg config.GCConfig, root string) []client.PruneInfo {
 			All:          rule.All,
 			KeepBytes:    rule.KeepBytes.AsBytes(root),
 			KeepDuration: rule.KeepDuration.Duration,
+			FreeBytes:    rule.FreeBytes.AsBytes(root),
 		})
 	}
 	return out