Introduce test remote plugin in dnet

There are multiple goals of introducing test driver plugin
  - Need a driver which can be configured to simulate
    different driver behaviors
  - For pure libnetwork multi-host integration testing
    a test driver configured for global scope can be used
    without trying to use a real driver like overlay
    which comes with it's own dependencies which can't
    be satisfied all enviroments(I am looking at you
    circleci)

This PR also makes all test cases that we have so far to be run
in circleci without any skipping needed.

Signed-off-by: Jana Radhakrishnan <mrjana@docker.com>

libnetwork/cmd/dnet/dnet.go

@@ -7,6 +7,7 @@ import (
 	"io"
 	"io/ioutil"
 	"net/http"
+	"net/http/httptest"
 	"os"
 	"strings"
 
@@ -19,6 +20,7 @@ import (
 	"github.com/docker/libnetwork"
 	"github.com/docker/libnetwork/api"
 	"github.com/docker/libnetwork/config"
+	"github.com/docker/libnetwork/driverapi"
 	"github.com/docker/libnetwork/netlabel"
 	"github.com/docker/libnetwork/options"
 	"github.com/gorilla/mux"
@@ -134,6 +136,10 @@ type dnetConnection struct {
 }
 
 func (d *dnetConnection) dnetDaemon(cfgFile string) error {
+	if err := startTestDriver(); err != nil {
+		return fmt.Errorf("failed to start test driver: %v\n", err)
+	}
+
 	cfg, err := parseConfig(cfgFile)
 	var cOptions []config.Option
 	if err == nil {
@@ -162,6 +168,64 @@ func (d *dnetConnection) dnetDaemon(cfgFile string) error {
 	return http.ListenAndServe(d.addr, r)
 }
 
+func startTestDriver() error {
+	mux := http.NewServeMux()
+	server := httptest.NewServer(mux)
+	if server == nil {
+		return fmt.Errorf("Failed to start a HTTP Server")
+	}
+
+	mux.HandleFunc("/Plugin.Activate", func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/vnd.docker.plugins.v1+json")
+		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")
+		fmt.Fprintf(w, `{"Scope":"global"}`)
+	})
+
+	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")
+		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")
+		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")
+		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")
+		fmt.Fprintf(w, "null")
+	})
+
+	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")
+		fmt.Fprintf(w, "null")
+	})
+
+	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")
+		fmt.Fprintf(w, "null")
+	})
+
+	if err := os.MkdirAll("/usr/share/docker/plugins", 0755); err != nil {
+		return err
+	}
+
+	if err := ioutil.WriteFile("/usr/share/docker/plugins/test.spec", []byte(server.URL), 0644); err != nil {
+		return err
+	}
+
+	return nil
+}
+
 func newDnetConnection(val string) (*dnetConnection, error) {
 	url, err := parsers.ParseHost(DefaultHTTPHost, DefaultUnixSocket, val)
 	if err != nil {

libnetwork/drivers/remote/driver.go

@@ -192,8 +192,8 @@ func (d *driver) Join(nid, eid string, sboxKey string, jinfo driverapi.JoinInfo,
 	}
 
 	ifaceName := res.InterfaceName
-	if ifaceName == nil {
-		return fmt.Errorf("no interface name information received")
+	if jinfo.InterfaceName() != nil && ifaceName == nil {
+		return fmt.Errorf("no interface name information received while one is expected")
 	}
 
 	if iface := jinfo.InterfaceName(); iface != nil {

libnetwork/test/integration/dnet/simple.bats

@@ -5,7 +5,7 @@ load helpers
 function setup() {
     if [ "${BATS_TEST_NUMBER}" -eq 1 ]; then
 	start_consul
-	start_dnet 1 simple multihost overlay
+	start_dnet 1 simple multihost test
     fi
 }
 
@@ -26,12 +26,13 @@ function teardown() {
     driver=$(echo ${lines[1]} | cut -d" " -f3)
     echo ${name} ${driver}
     [ "$name" = "multihost" ]
-    [ "$driver" = "overlay" ]
+    [ "$driver" = "test" ]
 }
 
 @test "Test network create" {
     echo $(docker ps)
-    run dnet_cmd $(inst_id2port 1) network create -d overlay mh1
+    run dnet_cmd $(inst_id2port 1) network create -d test mh1
+    echo ${output}
     [ "$status" -eq 0 ]
     line=$(dnet_cmd $(inst_id2port 1) network ls | grep mh1)
     echo ${line}
@@ -39,13 +40,13 @@ function teardown() {
     driver=$(echo ${line} | cut -d" " -f3)
     echo ${name} ${driver}
     [ "$name" = "mh1" ]
-    [ "$driver" = "overlay" ]
+    [ "$driver" = "test" ]
     dnet_cmd $(inst_id2port 1) network rm mh1
 }
 
 @test "Test network delete with id" {
     echo $(docker ps)
-    run dnet_cmd $(inst_id2port 1) network create -d overlay mh1
+    run dnet_cmd $(inst_id2port 1) network create -d test mh1
     [ "$status" -eq 0 ]
     echo ${output}
     dnet_cmd $(inst_id2port 1) network rm ${output}
@@ -82,7 +83,6 @@ function teardown() {
 }
 
 @test "Test service attach" {
-    skip_for_circleci
     echo $(docker ps)
     dnet_cmd $(inst_id2port 1) service publish svc1.multihost
     dnet_cmd $(inst_id2port 1) container create container_1