无法构建 docker 镜像，“必须是 root 用户”

我正在通过在容器内安装一个应用程序（应该是安装的 root 用户）来创建一个 Docker 镜像。

# cat Dockerfile 
FROM ubuntu:16.04
COPY $pwd/intel_virtual_gateway_console64_1_9_0.tar /root/
COPY $pwd/login.exp /root/
WORKDIR /root/
RUN tar -xvf intel_virtual_gateway_console64_1_9_0.tar 
RUN apt-get update && apt-get install -y expect \
                      expect-dev \
                      libxml2-utils
RUN whoami
RUN expect login.exp

docker镜像的构建过程：

root@labadmin-VirtualBox:~/RAGHU/krishna# docker build -t release:4.0 .
Sending build context to Docker daemon  633.5MB
Step 1/8 : FROM ubuntu:16.04
 ---> 6a2f32de169d
Step 2/8 : COPY $pwd/intel_virtual_gateway_console64_1_9_0.tar /root/
 ---> Using cache
 ---> 36e9ea407082
Step 3/8 : COPY $pwd/login.exp /root/
 ---> Using cache
 ---> 0fad538973d4
Step 4/8 : WORKDIR /root/
 ---> Using cache
 ---> f5d7f36bc37f
Step 5/8 : RUN tar -xvf intel_virtual_gateway_console64_1_9_0.tar
 ---> Using cache
 ---> 6cab428f1bc2
Step 6/8 : RUN apt-get update && apt-get install -y expect                       expect-dev                       libxml2-utils
 ---> Using cache
 ---> 5bb1ee67332f

要确认容器以 root 用户身份运行：

Step 7/8 : RUN whoami
 ---> Running in 112b87d77a08
root
 ---> 0c7eb38cc06b
Removing intermediate container 112b87d77a08
Step 8/8 : RUN expect login.exp
 ---> Running in 5f186baf2f8d
spawn ./virtualgatewayconsole_package/virtual_gateway_console_intel64
Install Error
--------------------------------------------------------------------------------
To install the application, you must be a root user.
--------------------------------------------------------------------------------
Type any key to exit: ^C

即使以 root 用户身份运行，也无法找出应用程序安装失败的原因。

编辑：添加 login.exp 脚本：这个脚本是完成我的功能的基础。

#cat login.exp 
#!/usr/bin/expect -f

if 0 {
     *************************READ THIS BEFORE START*********************
     User password must consist of at least 3 of the following categories: 
     uppercase, lowercase, numeric, and non-alphanumeric. In case of violation
     of this rule the Installation will fail!
     ********************************************************************
     }
set passwd "ISHAAN@p2017"
set username "raghu"

spawn ./virtualgatewayconsole_package/virtual_gateway_console_intel64
expect "Press Enter key to continue or q to quit:" 
send "\n" 

expect "Press ENTER for more, or q when done"  
send "q" 

sleep 5
#expect "conditions of this license agreement?"
expect "*(accept/decline): "  
send "accept\n" 

#Product installation
expect "*Please type a selection \[1\]:" 
send "\n" 

expect "*Please type a selection (Press Enter to next):" 
send "\n" 

sleep 2
#Configure TLS settings
expect "*Enter TLS keystore password (only numbers, letters and !@#$%^*()_+{}|.:?=-):"
send $passwd
send "\n"

expect "*Retype TLS keystore password:"
send $passwd
send "\n"

sleep 2
expect "Please type a selection (Press Enter to next):"
send "\n"

#Configure host
expect "Please type a selection (Press Enter to next):"
send "\n"

expect "Please type a selection (Press Enter to next):"
send "\n"

#Configure user for logging on the management console
expect "Please type a selection (Press Enter to next):"
send "\n"

sleep 2
expect "Enter user password (only numbers, letters, spaces and !@#$%^*()_+{}|.:?=-):"
send $passwd
send "\n"

expect "Retype user password:"
send $passwd
send "\n"

expect "Please type a selection (Press Enter to next):"
send "\n"

sleep 2
#Configure PostgreSQL service
expect "Please type a selection (Press Enter to next):"
send "\n"

expect "Enter PostgreSQL user password (only numbers, letters and !@#$%^*()_+{}|.:?=-):"
send $passwd
send "\n"

expect "Retype PostgreSQL user password:"
send $passwd
send "\n"

expect "Please type a selection (Press Enter to next):" 
send "\n"

sleep 60
#Create Keystore
expect "What is your first and last name?"
send $username
send "\n"

expect "What is the name of your organizational unit?"
send "radisys"
send "\n"

expect "What is the name of your organization?"
send "radisys"
send "\n"

sleep 2
expect "What is the name of your City or Locality?"
send "banglore"
send "\n"

expect "What is the name of your State or Province?"
send "karnataka"
send "\n"

expect "What is the two-letter country code for this unit?"
send "IND"
send "\n"

sleep 2
expect "Is CN=raghu, OU=radisys, O=radisys, L=banglore, ST=karnataka, C=IND correct?"
send "yes"
send "\n"

sleep 2
expect "Please type a selection \[q\]:"
send "q"

expect eof