controller: remove remaining parts of the controller

Removes all references to the controller and moves the remaining
sections of code to other packages.

Processes has been moved to monitor where it is used and the data
structs have been removed so buildflags is used directly. The controller
build function has been moved to the commands package.

Signed-off-by: Jonathan A. Sternberg <jonathan.sternberg@docker.com>

util/buildflags/attests.go

@@ -7,7 +7,6 @@ import (
 	"strconv"
 	"strings"
 
-	controllerapi "github.com/docker/buildx/controller/pb"
 	"github.com/pkg/errors"
 	"github.com/tonistiigi/go-csvvalue"
 )
@@ -33,16 +32,32 @@ func (a Attests) Normalize() Attests {
 	return removeAttestDupes(a)
 }
 
-func (a Attests) ToPB() []*controllerapi.Attest {
-	if len(a) == 0 {
-		return nil
-	}
+func (a Attests) ToMap() map[string]*string {
+	result := map[string]*string{}
+	for _, attest := range a {
+		// ignore duplicates
+		if _, ok := result[attest.Type]; ok {
+			continue
+		}
 
-	entries := make([]*controllerapi.Attest, len(a))
-	for i, entry := range a {
-		entries[i] = entry.ToPB()
+		if attest.Disabled {
+			result[attest.Type] = nil
+			continue
+		}
+
+		var b csvBuilder
+		if attest.Type != "" {
+			b.Write("type", attest.Type)
+		}
+		if attest.Disabled {
+			b.Write("disabled", "true")
+		}
+		b.WriteAttributes(attest.Attrs)
+
+		s := b.String()
+		result[attest.Type] = &s
 	}
-	return entries
+	return result
 }
 
 type Attest struct {
@@ -72,23 +87,6 @@ func (a *Attest) String() string {
 	return b.String()
 }
 
-func (a *Attest) ToPB() *controllerapi.Attest {
-	var b csvBuilder
-	if a.Type != "" {
-		b.Write("type", a.Type)
-	}
-	if a.Disabled {
-		b.Write("disabled", "true")
-	}
-	b.WriteAttributes(a.Attrs)
-
-	return &controllerapi.Attest{
-		Type:     a.Type,
-		Disabled: a.Disabled,
-		Attrs:    b.String(),
-	}
-}
-
 func (a *Attest) MarshalJSON() ([]byte, error) {
 	m := make(map[string]any, len(a.Attrs)+2)
 	for k, v := range a.Attrs {
@@ -182,7 +180,7 @@ func CanonicalizeAttest(attestType string, in string) string {
 	return fmt.Sprintf("type=%s,%s", attestType, in)
 }
 
-func ParseAttests(in []string) ([]*controllerapi.Attest, error) {
+func ParseAttests(in []string) (Attests, error) {
 	var outs []*Attest
 	for _, s := range in {
 		var out Attest
@@ -191,66 +189,7 @@ func ParseAttests(in []string) ([]*controllerapi.Attest, error) {
 		}
 		outs = append(outs, &out)
 	}
-	return ConvertAttests(outs)
-}
-
-// ConvertAttests converts Attestations for the controller API from
-// the ones in this package.
-//
-// Attestations of the same type will cause an error. Some tools,
-// like bake, remove the duplicates before calling this function.
-func ConvertAttests(in []*Attest) ([]*controllerapi.Attest, error) {
-	out := make([]*controllerapi.Attest, 0, len(in))
-
-	// Check for duplicate attestations while we convert them
-	// to the controller API.
-	found := map[string]struct{}{}
-	for _, attest := range in {
-		if _, ok := found[attest.Type]; ok {
-			return nil, errors.Errorf("duplicate attestation field %s", attest.Type)
-		}
-		found[attest.Type] = struct{}{}
-		out = append(out, attest.ToPB())
-	}
-	return out, nil
-}
-
-func ParseAttest(in string) (*controllerapi.Attest, error) {
-	if in == "" {
-		return nil, nil
-	}
-
-	fields, err := csvvalue.Fields(in, nil)
-	if err != nil {
-		return nil, err
-	}
-
-	attest := controllerapi.Attest{
-		Attrs: in,
-	}
-	for _, field := range fields {
-		key, value, ok := strings.Cut(field, "=")
-		if !ok {
-			return nil, errors.Errorf("invalid value %s", field)
-		}
-		key = strings.TrimSpace(strings.ToLower(key))
-
-		switch key {
-		case "type":
-			attest.Type = value
-		case "disabled":
-			disabled, err := strconv.ParseBool(value)
-			if err != nil {
-				return nil, errors.Wrapf(err, "invalid value %s", field)
-			}
-			attest.Disabled = disabled
-		}
-	}
-	if attest.Type == "" {
-		return nil, errors.Errorf("attestation type not specified")
-	}
-
-	return &attest, nil
+	return outs, nil
 }
 
 func removeAttestDupes(s []*Attest) []*Attest {