@@ -36,6 +36,15 @@ func NewArgs(initialArgs ...KeyValuePair) Args {

 	return args

 }

+// Keys returns all the keys in list of Args

+func (args Args) Keys() []string {

+	keys := make([]string, 0, len(args.fields))

+	for k := range args.fields {

+		keys = append(keys, k)

+	}

+	return keys

+}

+

 // MarshalJSON returns a JSON byte representation of the Args

 func (args Args) MarshalJSON() ([]byte, error) {

 	if len(args.fields) == 0 {

@@ -8,6 +8,7 @@ import (

 	"github.com/containerd/containerd/content/local"

 	"github.com/containerd/containerd/platforms"

 	"github.com/docker/docker/api/types"

+	"github.com/docker/docker/api/types/filters"

 	"github.com/docker/docker/builder/builder-next/adapters/containerimage"

 	"github.com/docker/docker/builder/builder-next/adapters/localinlinecache"

 	"github.com/docker/docker/builder/builder-next/adapters/snapshot"

@@ -232,7 +233,7 @@ func getGCPolicy(conf config.BuilderConfig, root string) ([]client.PruneInfo, er

 				gcPolicy[i], err = toBuildkitPruneInfo(types.BuildCachePruneOptions{

 					All:         p.All,

 					KeepStorage: b,

-					Filters:     p.Filter,

+					Filters:     filters.Args(p.Filter),

 				})

 				if err != nil {

 					return nil, err

@@ -1,12 +1,57 @@

 package config

-import "github.com/docker/docker/api/types/filters"

+import (

+	"encoding/json"

+	"fmt"

+	"sort"

+	"strings"

+

+	"github.com/docker/docker/api/types/filters"

+)

 // BuilderGCRule represents a GC rule for buildkit cache

 type BuilderGCRule struct {

-	All         bool         `json:",omitempty"`

-	Filter      filters.Args `json:",omitempty"`

-	KeepStorage string       `json:",omitempty"`

+	All         bool            `json:",omitempty"`

+	Filter      BuilderGCFilter `json:",omitempty"`

+	KeepStorage string          `json:",omitempty"`

+}

+

+// BuilderGCFilter contains garbage-collection filter rules for a BuildKit builder

+type BuilderGCFilter filters.Args

+

+// MarshalJSON returns a JSON byte representation of the BuilderGCFilter

+func (x *BuilderGCFilter) MarshalJSON() ([]byte, error) {

+	f := filters.Args(*x)

+	keys := f.Keys()

+	sort.Strings(keys)

+	arr := make([]string, 0, len(keys))

+	for _, k := range keys {

+		values := f.Get(k)

+		for _, v := range values {

+			arr = append(arr, fmt.Sprintf("%s=%s", k, v))

+		}

+	}

+	return json.Marshal(arr)

+}

+

+// UnmarshalJSON fills the BuilderGCFilter values structure from JSON input

+func (x *BuilderGCFilter) UnmarshalJSON(data []byte) error {

+	var arr []string

+	f := filters.NewArgs()

+	if err := json.Unmarshal(data, &arr); err != nil {

+		// backwards compat for deprecated buggy form

+		err := json.Unmarshal(data, &f)

+		*x = BuilderGCFilter(f)

+		return err

+	}

+	for _, s := range arr {

+		fields := strings.SplitN(s, "=", 2)

+		name := strings.ToLower(strings.TrimSpace(fields[0]))

+		value := strings.TrimSpace(fields[1])

+		f.Add(name, value)

+	}

+	*x = BuilderGCFilter(f)

+	return nil

 }

 // BuilderGCConfig contains GC config for a buildkit builder

new file mode 100644

@@ -0,0 +1,44 @@

+package config

+

+import (

+	"testing"

+

+	"github.com/docker/docker/api/types/filters"

+	"github.com/google/go-cmp/cmp"

+	"gotest.tools/assert"

+	"gotest.tools/fs"

+)

+

+func TestBuilderGC(t *testing.T) {

+	tempFile := fs.NewFile(t, "config", fs.WithContent(`{

+  "builder": {

+    "gc": {

+      "enabled": true,

+      "policy": [

+        {"keepStorage": "10GB", "filter": ["unused-for=2200h"]},

+        {"keepStorage": "50GB", "filter": {"unused-for": {"3300h": true}}},

+        {"keepStorage": "100GB", "all": true}

+      ]

+    }

+  }

+}`))

+	defer tempFile.Remove()

+	configFile := tempFile.Path()

+

+	cfg, err := MergeDaemonConfigurations(&Config{}, nil, configFile)

+	assert.NilError(t, err)

+	assert.Assert(t, cfg.Builder.GC.Enabled)

+	f1 := filters.NewArgs()

+	f1.Add("unused-for", "2200h")

+	f2 := filters.NewArgs()

+	f2.Add("unused-for", "3300h")

+	expectedPolicy := []BuilderGCRule{

+		{KeepStorage: "10GB", Filter: BuilderGCFilter(f1)},

+		{KeepStorage: "50GB", Filter: BuilderGCFilter(f2)}, /* parsed from deprecated form */

+		{KeepStorage: "100GB", All: true},

+	}

+	assert.DeepEqual(t, cfg.Builder.GC.Policy, expectedPolicy, cmp.AllowUnexported(BuilderGCFilter{}))

+	// double check to please the skeptics

+	assert.Assert(t, filters.Args(cfg.Builder.GC.Policy[0].Filter).UniqueExactMatch("unused-for", "2200h"))

+	assert.Assert(t, filters.Args(cfg.Builder.GC.Policy[1].Filter).UniqueExactMatch("unused-for", "3300h"))

+}