func (s *DockerServer) CustomHandler(path string, handler http.Handler) {
	s.handlerMutex.Lock()
	s.customHandlers[path] = handler
	s.handlerMutex.Unlock()
}
CustomHandler registers a custom handler for a specific path.

For example:

server.CustomHandler("/containers/json", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
http.Error(w, "Something wrong is not right", http.StatusInternalServerError)
}))
package testing
import (
	"archive/tar"
	"crypto/rand"
	"encoding/json"
	"errors"
	"fmt"
	mathrand "math/rand"
	"net"
	"net/http"
	"regexp"
	"strconv"
	"strings"
	"sync"
	"time"
	"github.com/fsouza/go-dockerclient"
	"github.com/fsouza/go-dockerclient/external/github.com/docker/docker/pkg/stdcopy"
	"github.com/fsouza/go-dockerclient/external/github.com/gorilla/mux"
)
var nameRegexp = regexp.MustCompile(`^[a-zA-Z0-9][a-zA-Z0-9_.-]+$`)
type DockerServer struct {
	containers     []*docker.Container
	execs          []*docker.ExecInspect
	execMut        sync.RWMutex
	cMut           sync.RWMutex
	images         []docker.Image
	iMut           sync.RWMutex
	imgIDs         map[string]string
	listener       net.Listener
	mux            *mux.Router
	hook           func(*http.Request)
	failures       map[string]string
	multiFailures  []map[string]string
	execCallbacks  map[string]func()
	statsCallbacks map[string]func(string) docker.Stats
	customHandlers map[string]http.Handler
	handlerMutex   sync.RWMutex
	cChan          chan<- *docker.Container
}
func NewServer(bind string, containerChan chan<- *docker.Container, hook func(*http.Request)) (*DockerServer, error) {
	listener, err := net.Listen("tcp", bind)
	if err != nil {
		return nil, err
	}
	server := DockerServer{
		listener:       listener,
		imgIDs:         make(map[string]string),
		hook:           hook,
		failures:       make(map[string]string),
		execCallbacks:  make(map[string]func()),
		statsCallbacks: make(map[string]func(string) docker.Stats),
		customHandlers: make(map[string]http.Handler),
		cChan:          containerChan,
	}
	server.buildMuxer()
	go http.Serve(listener, &server)
	return &server, nil
}
func (s *DockerServer) notify(container *docker.Container) {
	if s.cChan != nil {
		s.cChan <- container
	}
}
func (s *DockerServer) buildMuxer() {
	s.mux = mux.NewRouter()
	s.mux.Path("/commit").Methods("POST").HandlerFunc(s.handlerWrapper(s.commitContainer))
	s.mux.Path("/containers/json").Methods("GET").HandlerFunc(s.handlerWrapper(s.listContainers))
	s.mux.Path("/containers/create").Methods("POST").HandlerFunc(s.handlerWrapper(s.createContainer))
	s.mux.Path("/containers/{id:.*}/json").Methods("GET").HandlerFunc(s.handlerWrapper(s.inspectContainer))
	s.mux.Path("/containers/{id:.*}/rename").Methods("POST").HandlerFunc(s.handlerWrapper(s.renameContainer))
	s.mux.Path("/containers/{id:.*}/top").Methods("GET").HandlerFunc(s.handlerWrapper(s.topContainer))
	s.mux.Path("/containers/{id:.*}/start").Methods("POST").HandlerFunc(s.handlerWrapper(s.startContainer))
	s.mux.Path("/containers/{id:.*}/kill").Methods("POST").HandlerFunc(s.handlerWrapper(s.stopContainer))
	s.mux.Path("/containers/{id:.*}/stop").Methods("POST").HandlerFunc(s.handlerWrapper(s.stopContainer))
	s.mux.Path("/containers/{id:.*}/pause").Methods("POST").HandlerFunc(s.handlerWrapper(s.pauseContainer))
	s.mux.Path("/containers/{id:.*}/unpause").Methods("POST").HandlerFunc(s.handlerWrapper(s.unpauseContainer))
	s.mux.Path("/containers/{id:.*}/wait").Methods("POST").HandlerFunc(s.handlerWrapper(s.waitContainer))
	s.mux.Path("/containers/{id:.*}/attach").Methods("POST").HandlerFunc(s.handlerWrapper(s.attachContainer))
	s.mux.Path("/containers/{id:.*}").Methods("DELETE").HandlerFunc(s.handlerWrapper(s.removeContainer))
	s.mux.Path("/containers/{id:.*}/exec").Methods("POST").HandlerFunc(s.handlerWrapper(s.createExecContainer))
	s.mux.Path("/containers/{id:.*}/stats").Methods("GET").HandlerFunc(s.handlerWrapper(s.statsContainer))
	s.mux.Path("/exec/{id:.*}/resize").Methods("POST").HandlerFunc(s.handlerWrapper(s.resizeExecContainer))
	s.mux.Path("/exec/{id:.*}/start").Methods("POST").HandlerFunc(s.handlerWrapper(s.startExecContainer))
	s.mux.Path("/exec/{id:.*}/json").Methods("GET").HandlerFunc(s.handlerWrapper(s.inspectExecContainer))
	s.mux.Path("/images/create").Methods("POST").HandlerFunc(s.handlerWrapper(s.pullImage))
	s.mux.Path("/build").Methods("POST").HandlerFunc(s.handlerWrapper(s.buildImage))
	s.mux.Path("/images/json").Methods("GET").HandlerFunc(s.handlerWrapper(s.listImages))
	s.mux.Path("/images/{id:.*}").Methods("DELETE").HandlerFunc(s.handlerWrapper(s.removeImage))
	s.mux.Path("/images/{name:.*}/json").Methods("GET").HandlerFunc(s.handlerWrapper(s.inspectImage))
	s.mux.Path("/images/{name:.*}/push").Methods("POST").HandlerFunc(s.handlerWrapper(s.pushImage))
	s.mux.Path("/images/{name:.*}/tag").Methods("POST").HandlerFunc(s.handlerWrapper(s.tagImage))
	s.mux.Path("/events").Methods("GET").HandlerFunc(s.listEvents)
	s.mux.Path("/_ping").Methods("GET").HandlerFunc(s.handlerWrapper(s.pingDocker))
	s.mux.Path("/images/load").Methods("POST").HandlerFunc(s.handlerWrapper(s.loadImage))
	s.mux.Path("/images/{id:.*}/get").Methods("GET").HandlerFunc(s.handlerWrapper(s.getImage))
}
func (s *DockerServer) SetHook(hook func(*http.Request)) {
	s.hook = hook
}
func (s *DockerServer) PrepareExec(id string, callback func()) {
	s.execCallbacks[id] = callback
}
func (s *DockerServer) PrepareStats(id string, callback func(string) docker.Stats) {
	s.statsCallbacks[id] = callback
}
func (s *DockerServer) PrepareFailure(id string, urlRegexp string) {
	s.failures[id] = urlRegexp
}
func (s *DockerServer) PrepareMultiFailures(id string, urlRegexp string) {
	s.multiFailures = append(s.multiFailures, map[string]string{"error": id, "url": urlRegexp})
}
func (s *DockerServer) ResetFailure(id string) {
	delete(s.failures, id)
}
func (s *DockerServer) ResetMultiFailures() {
	s.multiFailures = []map[string]string{}
}