add `docker network prune`

`docker network prune` prunes unused networks, including overlay ones.
`docker system prune` also prunes unused networks.

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

interface.go

@@ -91,6 +91,7 @@ type NetworkAPIClient interface {
 	NetworkInspectWithRaw(ctx context.Context, networkID string) (types.NetworkResource, []byte, error)
 	NetworkList(ctx context.Context, options types.NetworkListOptions) ([]types.NetworkResource, error)
 	NetworkRemove(ctx context.Context, networkID string) error
+	NetworksPrune(ctx context.Context, cfg types.NetworksPruneConfig) (types.NetworksPruneReport, error)
 }
 
 // NodeAPIClient defines API client methods for the nodes

network_prune.go

@@ -0,0 +1,26 @@
+package client
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"github.com/docker/docker/api/types"
+	"golang.org/x/net/context"
+)
+
+// NetworksPrune requests the daemon to delete unused networks
+func (cli *Client) NetworksPrune(ctx context.Context, cfg types.NetworksPruneConfig) (types.NetworksPruneReport, error) {
+	var report types.NetworksPruneReport
+
+	serverResp, err := cli.post(ctx, "/networks/prune", nil, cfg, nil)
+	if err != nil {
+		return report, err
+	}
+	defer ensureReaderClosed(serverResp)
+
+	if err := json.NewDecoder(serverResp.body).Decode(&report); err != nil {
+		return report, fmt.Errorf("Error retrieving network prune report: %v", err)
+	}
+
+	return report, nil
+}