Merge pull request moby#46080 from thaJeztah/pkg_plugin_cleanup_STEP2

pkg/plugins: some cleaning up (step 2)

integration-cli/docker_cli_external_volume_driver_test.go

@@ -16,6 +16,7 @@ import (
 	"github.com/docker/docker/api/types"
 	volumetypes "github.com/docker/docker/api/types/volume"
 	"github.com/docker/docker/integration-cli/daemon"
+	"github.com/docker/docker/pkg/plugins"
 	"github.com/docker/docker/pkg/stringid"
 	testdaemon "github.com/docker/docker/testutil/daemon"
 	"github.com/docker/docker/volume"
@@ -104,10 +105,10 @@ func newVolumePlugin(c *testing.T, name string) *volumePlugin {
 		case error:
 			http.Error(w, t.Error(), 500)
 		case string:
-			w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+			w.Header().Set("Content-Type", plugins.VersionMimetype)
 			fmt.Fprintln(w, t)
 		default:
-			w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+			w.Header().Set("Content-Type", plugins.VersionMimetype)
 			json.NewEncoder(w).Encode(&data)
 		}
 	}

integration-cli/docker_cli_network_unix_test.go

@@ -22,6 +22,7 @@ import (
 	"github.com/docker/docker/libnetwork/ipamapi"
 	remoteipam "github.com/docker/docker/libnetwork/ipams/remote/api"
 	"github.com/docker/docker/libnetwork/netlabel"
+	"github.com/docker/docker/pkg/plugins"
 	"github.com/docker/docker/pkg/stringid"
 	"github.com/docker/docker/runconfig"
 	testdaemon "github.com/docker/docker/testutil/daemon"
@@ -58,13 +59,13 @@ func (s *DockerNetworkSuite) SetUpSuite(c *testing.T) {
 
 func setupRemoteNetworkDrivers(c *testing.T, mux *http.ServeMux, url, netDrv, ipamDrv string) {
 	mux.HandleFunc("/Plugin.Activate", func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, `{"Implements": ["%s", "%s"]}`, driverapi.NetworkPluginEndpointType, ipamapi.PluginEndpointType)
 	})
 
 	// Network driver implementation
 	mux.HandleFunc(fmt.Sprintf("/%s.GetCapabilities", driverapi.NetworkPluginEndpointType), func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, `{"Scope":"local"}`)
 	})
 
@@ -74,22 +75,22 @@ func setupRemoteNetworkDrivers(c *testing.T, mux *http.ServeMux, url, netDrv, ip
 			http.Error(w, "Unable to decode JSON payload: "+err.Error(), http.StatusBadRequest)
 			return
 		}
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, "null")
 	})
 
 	mux.HandleFunc(fmt.Sprintf("/%s.DeleteNetwork", driverapi.NetworkPluginEndpointType), func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, "null")
 	})
 
 	mux.HandleFunc(fmt.Sprintf("/%s.CreateEndpoint", driverapi.NetworkPluginEndpointType), func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, `{"Interface":{"MacAddress":"a0:b1:c2:d3:e4:f5"}}`)
 	})
 
 	mux.HandleFunc(fmt.Sprintf("/%s.Join", driverapi.NetworkPluginEndpointType), func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 
 		veth := &netlink.Veth{
 			LinkAttrs: netlink.LinkAttrs{Name: "randomIfName", TxQLen: 0}, PeerName: "cnt0",
@@ -102,12 +103,12 @@ func setupRemoteNetworkDrivers(c *testing.T, mux *http.ServeMux, url, netDrv, ip
 	})
 
 	mux.HandleFunc(fmt.Sprintf("/%s.Leave", driverapi.NetworkPluginEndpointType), func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, "null")
 	})
 
 	mux.HandleFunc(fmt.Sprintf("/%s.DeleteEndpoint", driverapi.NetworkPluginEndpointType), func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		if link, err := netlink.LinkByName("cnt0"); err == nil {
 			netlink.LinkDel(link)
 		}
@@ -128,7 +129,7 @@ func setupRemoteNetworkDrivers(c *testing.T, mux *http.ServeMux, url, netDrv, ip
 	)
 
 	mux.HandleFunc(fmt.Sprintf("/%s.GetDefaultAddressSpaces", ipamapi.PluginEndpointType), func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, `{"LocalDefaultAddressSpace":"`+lAS+`", "GlobalDefaultAddressSpace": "`+gAS+`"}`)
 	})
 
@@ -138,7 +139,7 @@ func setupRemoteNetworkDrivers(c *testing.T, mux *http.ServeMux, url, netDrv, ip
 			http.Error(w, "Unable to decode JSON payload: "+err.Error(), http.StatusBadRequest)
 			return
 		}
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		if poolRequest.AddressSpace != lAS && poolRequest.AddressSpace != gAS {
 			fmt.Fprintf(w, `{"Error":"Unknown address space in pool request: `+poolRequest.AddressSpace+`"}`)
 		} else if poolRequest.Pool != "" && poolRequest.Pool != pool {
@@ -154,7 +155,7 @@ func setupRemoteNetworkDrivers(c *testing.T, mux *http.ServeMux, url, netDrv, ip
 			http.Error(w, "Unable to decode JSON payload: "+err.Error(), http.StatusBadRequest)
 			return
 		}
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		// make sure libnetwork is now querying on the expected pool id
 		if addressRequest.PoolID != poolID {
 			fmt.Fprintf(w, `{"Error":"unknown pool id"}`)
@@ -171,7 +172,7 @@ func setupRemoteNetworkDrivers(c *testing.T, mux *http.ServeMux, url, netDrv, ip
 			http.Error(w, "Unable to decode JSON payload: "+err.Error(), http.StatusBadRequest)
 			return
 		}
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		// make sure libnetwork is now asking to release the expected address from the expected poolid
 		if addressRequest.PoolID != poolID {
 			fmt.Fprintf(w, `{"Error":"unknown pool id"}`)
@@ -188,7 +189,7 @@ func setupRemoteNetworkDrivers(c *testing.T, mux *http.ServeMux, url, netDrv, ip
 			http.Error(w, "Unable to decode JSON payload: "+err.Error(), http.StatusBadRequest)
 			return
 		}
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		// make sure libnetwork is now asking to release the expected poolid
 		if addressRequest.PoolID != poolID {
 			fmt.Fprintf(w, `{"Error":"unknown pool id"}`)

integration-cli/docker_cli_swarm_test.go

@@ -26,6 +26,7 @@ import (
 	"github.com/docker/docker/libnetwork/driverapi"
 	"github.com/docker/docker/libnetwork/ipamapi"
 	remoteipam "github.com/docker/docker/libnetwork/ipams/remote/api"
+	"github.com/docker/docker/pkg/plugins"
 	"github.com/moby/swarmkit/v2/ca/keyutils"
 	"github.com/vishvananda/netlink"
 	"gotest.tools/v3/assert"
@@ -617,13 +618,13 @@ const (
 
 func setupRemoteGlobalNetworkPlugin(c *testing.T, mux *http.ServeMux, url, netDrv, ipamDrv string) {
 	mux.HandleFunc("/Plugin.Activate", func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, `{"Implements": ["%s", "%s"]}`, driverapi.NetworkPluginEndpointType, ipamapi.PluginEndpointType)
 	})
 
 	// Network driver implementation
 	mux.HandleFunc(fmt.Sprintf("/%s.GetCapabilities", driverapi.NetworkPluginEndpointType), func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, `{"Scope":"global"}`)
 	})
 
@@ -633,12 +634,12 @@ func setupRemoteGlobalNetworkPlugin(c *testing.T, mux *http.ServeMux, url, netDr
 			http.Error(w, "Unable to decode JSON payload: "+err.Error(), http.StatusBadRequest)
 			return
 		}
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, "null")
 	})
 
 	mux.HandleFunc(fmt.Sprintf("/%s.FreeNetwork", driverapi.NetworkPluginEndpointType), func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, "null")
 	})
 
@@ -648,22 +649,22 @@ func setupRemoteGlobalNetworkPlugin(c *testing.T, mux *http.ServeMux, url, netDr
 			http.Error(w, "Unable to decode JSON payload: "+err.Error(), http.StatusBadRequest)
 			return
 		}
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, "null")
 	})
 
 	mux.HandleFunc(fmt.Sprintf("/%s.DeleteNetwork", driverapi.NetworkPluginEndpointType), func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, "null")
 	})
 
 	mux.HandleFunc(fmt.Sprintf("/%s.CreateEndpoint", driverapi.NetworkPluginEndpointType), func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, `{"Interface":{"MacAddress":"a0:b1:c2:d3:e4:f5"}}`)
 	})
 
 	mux.HandleFunc(fmt.Sprintf("/%s.Join", driverapi.NetworkPluginEndpointType), func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 
 		veth := &netlink.Veth{
 			LinkAttrs: netlink.LinkAttrs{Name: "randomIfName", TxQLen: 0}, PeerName: "cnt0",
@@ -676,12 +677,12 @@ func setupRemoteGlobalNetworkPlugin(c *testing.T, mux *http.ServeMux, url, netDr
 	})
 
 	mux.HandleFunc(fmt.Sprintf("/%s.Leave", driverapi.NetworkPluginEndpointType), func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, "null")
 	})
 
 	mux.HandleFunc(fmt.Sprintf("/%s.DeleteEndpoint", driverapi.NetworkPluginEndpointType), func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		if link, err := netlink.LinkByName("cnt0"); err == nil {
 			netlink.LinkDel(link)
 		}
@@ -702,7 +703,7 @@ func setupRemoteGlobalNetworkPlugin(c *testing.T, mux *http.ServeMux, url, netDr
 	)
 
 	mux.HandleFunc(fmt.Sprintf("/%s.GetDefaultAddressSpaces", ipamapi.PluginEndpointType), func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, `{"LocalDefaultAddressSpace":"`+lAS+`", "GlobalDefaultAddressSpace": "`+gAS+`"}`)
 	})
 
@@ -712,7 +713,7 @@ func setupRemoteGlobalNetworkPlugin(c *testing.T, mux *http.ServeMux, url, netDr
 			http.Error(w, "Unable to decode JSON payload: "+err.Error(), http.StatusBadRequest)
 			return
 		}
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		if poolRequest.AddressSpace != lAS && poolRequest.AddressSpace != gAS {
 			fmt.Fprintf(w, `{"Error":"Unknown address space in pool request: `+poolRequest.AddressSpace+`"}`)
 		} else if poolRequest.Pool != "" && poolRequest.Pool != pool {
@@ -728,7 +729,7 @@ func setupRemoteGlobalNetworkPlugin(c *testing.T, mux *http.ServeMux, url, netDr
 			http.Error(w, "Unable to decode JSON payload: "+err.Error(), http.StatusBadRequest)
 			return
 		}
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		// make sure libnetwork is now querying on the expected pool id
 		if addressRequest.PoolID != poolID {
 			fmt.Fprintf(w, `{"Error":"unknown pool id"}`)
@@ -745,7 +746,7 @@ func setupRemoteGlobalNetworkPlugin(c *testing.T, mux *http.ServeMux, url, netDr
 			http.Error(w, "Unable to decode JSON payload: "+err.Error(), http.StatusBadRequest)
 			return
 		}
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		// make sure libnetwork is now asking to release the expected address from the expected poolid
 		if addressRequest.PoolID != poolID {
 			fmt.Fprintf(w, `{"Error":"unknown pool id"}`)
@@ -762,7 +763,7 @@ func setupRemoteGlobalNetworkPlugin(c *testing.T, mux *http.ServeMux, url, netDr
 			http.Error(w, "Unable to decode JSON payload: "+err.Error(), http.StatusBadRequest)
 			return
 		}
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		// make sure libnetwork is now asking to release the expected poolid
 		if addressRequest.PoolID != poolID {
 			fmt.Fprintf(w, `{"Error":"unknown pool id"}`)

integration/plugin/graphdriver/external_test.go

@@ -126,7 +126,7 @@ func setupPlugin(t *testing.T, ec map[string]*graphEventsCounter, ext string, mu
 	}
 
 	respond := func(w http.ResponseWriter, data interface{}) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		switch t := data.(type) {
 		case error:
 			fmt.Fprintf(w, "{\"Err\": %q}\n", t.Error())

libnetwork/drivers/remote/driver_test.go

@@ -66,7 +66,7 @@ func setupPlugin(t *testing.T, name string, mux *http.ServeMux) func() {
 	}
 
 	mux.HandleFunc("/Plugin.Activate", func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, `{"Implements": ["%s"]}`, driverapi.NetworkPluginEndpointType)
 	})
 

libnetwork/ipams/remote/remote_test.go

@@ -61,7 +61,7 @@ func setupPlugin(t *testing.T, name string, mux *http.ServeMux) func() {
 	}
 
 	mux.HandleFunc("/Plugin.Activate", func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, `{"Implements": ["%s"]}`, ipamapi.PluginEndpointType)
 	})
 

libnetwork/libnetwork_test.go

@@ -1164,7 +1164,7 @@ func TestInvalidRemoteDriver(t *testing.T) {
 	defer server.Close()
 
 	mux.HandleFunc("/Plugin.Activate", func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintln(w, `{"Implements": ["InvalidDriver"]}`)
 	})
 
@@ -1207,19 +1207,19 @@ func TestValidRemoteDriver(t *testing.T) {
 	defer server.Close()
 
 	mux.HandleFunc("/Plugin.Activate", func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, `{"Implements": ["%s"]}`, driverapi.NetworkPluginEndpointType)
 	})
 	mux.HandleFunc(fmt.Sprintf("/%s.GetCapabilities", driverapi.NetworkPluginEndpointType), func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, `{"Scope":"local"}`)
 	})
 	mux.HandleFunc(fmt.Sprintf("/%s.CreateNetwork", driverapi.NetworkPluginEndpointType), func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, "null")
 	})
 	mux.HandleFunc(fmt.Sprintf("/%s.DeleteNetwork", driverapi.NetworkPluginEndpointType), func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintf(w, "null")
 	})
 

pkg/plugins/client.go

@@ -26,6 +26,9 @@ const (
 	dummyHost = "plugin.moby.localhost"
 )
 
+// VersionMimetype is the Content-Type the engine sends to plugins.
+const VersionMimetype = transport.VersionMimetype
+
 func newTransport(addr string, tlsConfig *tlsconfig.Options) (*transport.HTTPTransport, error) {
 	tr := &http.Transport{}
 

pkg/plugins/transport/transport.go → pkg/plugins/transport/mimetype.go

@@ -1,4 +1,6 @@
 package transport // import "github.com/docker/docker/pkg/plugins/transport"
 
 // VersionMimetype is the Content-Type the engine sends to plugins.
+//
+// For convenience, there is an alias in [github.com/docker/docker/pkg/plugins.VersionMimetype].
 const VersionMimetype = "application/vnd.docker.plugins.v1.2+json"

volume/drivers/proxy_test.go

@@ -18,42 +18,42 @@ func TestVolumeRequestError(t *testing.T) {
 	defer server.Close()
 
 	mux.HandleFunc("/VolumeDriver.Create", func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintln(w, `{"Err": "Cannot create volume"}`)
 	})
 
 	mux.HandleFunc("/VolumeDriver.Remove", func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintln(w, `{"Err": "Cannot remove volume"}`)
 	})
 
 	mux.HandleFunc("/VolumeDriver.Mount", func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintln(w, `{"Err": "Cannot mount volume"}`)
 	})
 
 	mux.HandleFunc("/VolumeDriver.Unmount", func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintln(w, `{"Err": "Cannot unmount volume"}`)
 	})
 
 	mux.HandleFunc("/VolumeDriver.Path", func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintln(w, `{"Err": "Unknown volume"}`)
 	})
 
 	mux.HandleFunc("/VolumeDriver.List", func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintln(w, `{"Err": "Cannot list volumes"}`)
 	})
 
 	mux.HandleFunc("/VolumeDriver.Get", func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		fmt.Fprintln(w, `{"Err": "Cannot get volume"}`)
 	})
 
 	mux.HandleFunc("/VolumeDriver.Capabilities", func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		w.Header().Set("Content-Type", plugins.VersionMimetype)
 		http.Error(w, "error", 500)
 	})