[swarm_docker] Pass entrypoint args directly from config.

Change-Id: I9b4a5659f9180b07eceb6c8063f3c3c22d8ad94e
diff --git a/cmd/swarm_docker/swarm_docker.go b/cmd/swarm_docker/swarm_docker.go
index 5bd3ed9..9244f20 100644
--- a/cmd/swarm_docker/swarm_docker.go
+++ b/cmd/swarm_docker/swarm_docker.go
@@ -49,7 +49,6 @@
 
 const (
 	registryDomain = "gcr.io"
-	swarmingURL    = "https://chromium-swarm.appspot.com"
 )
 
 var (
@@ -64,15 +63,14 @@
 
 // Config contains the service configuration.
 type Config struct {
-	Memory         int         `json:"memory"`
-	Cpus           int         `json:"cpus"`
-	User           string      `json:"user"`
-	NetworkMode    string      `json:"network_mode"`
-	ImageName      string      `json:"image_name"`
-	Project        string      `json:"project"`
-	SwarmingServer string      `json:"swarming_server"`
-	Credentials    string      `json:"credentials"`
-	Containers     []Container `json:"containers"`
+	Memory      int         `json:"memory"`
+	Cpus        int         `json:"cpus"`
+	NetworkMode string      `json:"network_mode"`
+	ImageName   string      `json:"image_name"`
+	Project     string      `json:"project"`
+	Credentials string      `json:"credentials"`
+	Containers  []Container `json:"containers"`
+	Cmd         []string    `json:"cmd,omitempty"`
 }
 
 // Container describes the container instance.
@@ -290,7 +288,7 @@
 		Hostname:   c.hostname,
 		Domainname: c.domainname, // should be same as host
 		Image:      fmt.Sprintf("%s/%s/%s", registryDomain, cfg.Project, cfg.ImageName),
-		Cmd:        []string{"-swarming-server", cfg.SwarmingServer, "-user", cfg.User},
+		Cmd:        cfg.Cmd,
 	}
 	hostConfig := container.HostConfig{
 		Resources: container.Resources{