Add SessionProvisioner and InstanceProvisionerFactory

Remove AllowedImages and IsDockerHost as it is not really being used for
anything useful

provisioner/overlay.go

@@ -0,0 +1,50 @@
+package provisioner
+
+import (
+	"fmt"
+	"log"
+	"net/url"
+	"strings"
+
+	"github.com/play-with-docker/play-with-docker/config"
+	"github.com/play-with-docker/play-with-docker/docker"
+	"github.com/play-with-docker/play-with-docker/pwd/types"
+)
+
+type overlaySessionProvisioner struct {
+	dockerFactory docker.FactoryApi
+}
+
+func NewOverlaySessionProvisioner(df docker.FactoryApi) SessionProvisionerApi {
+	return &overlaySessionProvisioner{dockerFactory: df}
+}
+
+func (p *overlaySessionProvisioner) SessionNew(s *types.Session) error {
+	dockerClient, err := p.dockerFactory.GetForSession(s.Id)
+	if err != nil {
+		// We assume we are out of capacity
+		return fmt.Errorf("Out of capacity")
+	}
+	u, _ := url.Parse(dockerClient.GetDaemonHost())
+	if u.Host == "" {
+		s.Host = "localhost"
+	} else {
+		chunks := strings.Split(u.Host, ":")
+		s.Host = chunks[0]
+	}
+
+	if err := dockerClient.CreateNetwork(s.Id); err != nil {
+		log.Println("ERROR NETWORKING", err)
+		return err
+	}
+	log.Printf("Network [%s] created for session [%s]\n", s.Id, s.Id)
+
+	ip, err := dockerClient.ConnectNetwork(config.L2ContainerName, s.Id, s.PwdIpAddress)
+	if err != nil {
+		log.Println(err)
+		return err
+	}
+	s.PwdIpAddress = ip
+	log.Printf("Connected %s to network [%s]\n", config.PWDContainerName, s.Id)
+	return nil
+}