Add qemu CSP for Coordinator

Signed-off-by: Daniel Weiße <dw@edgeless.systems>

coordinator/cloudprovider/qemu/metadata.go

@@ -0,0 +1,41 @@
+package qemu
+
+import (
+	"context"
+
+	"github.com/edgelesssys/constellation/coordinator/core"
+	"github.com/edgelesssys/constellation/coordinator/role"
+)
+
+// Metadata implements core.ProviderMetadata interface for QEMU (currently not supported).
+type Metadata struct{}
+
+// Supported is used to determine if metadata API is implemented for this cloud provider.
+func (m *Metadata) Supported() bool {
+	return false
+}
+
+// List retrieves all instances belonging to the current constellation.
+func (m *Metadata) List(ctx context.Context) ([]core.Instance, error) {
+	panic("function *Metadata.List not implemented")
+}
+
+// Self retrieves the current instance.
+func (m *Metadata) Self(ctx context.Context) (core.Instance, error) {
+	panic("function *Metdata.Self not implemented")
+}
+
+// GetInstance retrieves an instance using its providerID.
+func (m Metadata) GetInstance(ctx context.Context, providerID string) (core.Instance, error) {
+	panic("function *Metadata.GetInstance not implemented")
+}
+
+// SignalRole signals the constellation role via cloud provider metadata (if supported by the CSP and deployment type, otherwise does nothing).
+func (m Metadata) SignalRole(ctx context.Context, role role.Role) error {
+	panic("function *Metadata.SignalRole not implemented")
+}
+
+// SetVPNIP stores the internally used VPN IP in cloud provider metadata (if supported and required for autoscaling by the CSP, otherwise does nothing).
+func (m Metadata) SetVPNIP(ctx context.Context, vpnIP string) error {
+	panic("function *Metadata.SetVPNIP not implemented")
+}