define CapMountSSH

Signed-off-by: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>

client/llb/exec.go

@@ -270,6 +270,10 @@ func (e *ExecOp) Marshal(c *Constraints) (digest.Digest, []byte, *pb.OpMetadata,
 		addCap(&e.constraints, pb.CapMountSecret)
 	}
 
+	if len(e.ssh) > 0 {
+		addCap(&e.constraints, pb.CapMountSSH)
+	}
+
 	for _, s := range e.secrets {
 		pm := &pb.Mount{
 			Dest:      s.Target,

solver/pb/caps.go

@@ -40,6 +40,7 @@ const (
 	CapExecMountSelector       apicaps.CapID = "exec.mount.selector"
 	CapExecMountTmpfs          apicaps.CapID = "exec.mount.tmpfs"
 	CapMountSecret             apicaps.CapID = "exec.mount.secret"
+	CapMountSSH                apicaps.CapID = "exec.mount.ssh"
 
 	CapConstraints apicaps.CapID = "constraints"
 	CapPlatform    apicaps.CapID = "platform"
@@ -212,6 +213,12 @@ func init() {
 		Status:  apicaps.CapStatusExperimental,
 	})
 
+	Caps.Init(apicaps.Cap{
+		ID:      CapMountSSH,
+		Enabled: true,
+		Status:  apicaps.CapStatusExperimental,
+	})
+
 	Caps.Init(apicaps.Cap{
 		ID:      CapConstraints,
 		Enabled: true,