Can't open '/source/centos-7': No such file or directory at /usr/bin/spectool line 314.

[ghost]

Yes. Copied awx.spec to awx-build.spec .... still the same error ...

Seems that the error is not from awe-build.spec file or awx.spec file ..it is from the source directory :

-bash-4.2# cat /etc/redhat-release
CentOS Linux release 7.4.1708 (Core)
-bash-4.2# sh -x build.sh centos-7

set -e
set -x
SPECFILE=/source/centos-7
yum install -y rpmdevtools yum-utils fakeroot
Loaded plugins: fastestmirror
base | 3.6 kB 00:00:00
docker-ee-stable-17.06 | 2.9 kB 00:00:00
epel/x86_64/metalink | 17 kB 00:00:00
epel | 3.2 kB 00:00:00
extras | 3.4 kB 00:00:00
updates | 3.4 kB 00:00:00
(1/3): epel/x86_64/updateinfo | 932 kB 00:00:00
(2/3): docker-ee-stable-17.06/x86_64/primary_db | 13 kB 00:00:01
(3/3): epel/x86_64/primary | 3.5 MB 00:00:00
Loading mirror speeds from cached hostfile
base: mirror.hostduplex.com
epel: mirror.hmc.edu
extras: mirror.hostduplex.com
updates: mirror.hostduplex.com
epel 12585/12585
Package rpmdevtools-8.3-5.el7.noarch already installed and latest version
Package yum-utils-1.1.31-45.el7.noarch already installed and latest version
Package fakeroot-1.18.4-2.el7.x86_64 already installed and latest version
Nothing to do
useradd -s /bin/bash builder
useradd: warning: the home directory already exists.
Not copying any file from skel directory into it.
Creating mailbox file: File exists
chown builder. /cache -R
pushd /source
/source ~/awx-rpm-build/awx-rpm/buildhelpers
spectool -g /source/centos-7
Can't open '/source/centos-7': No such file or directory at /usr/bin/spectool line 314.
-bash-4.2#

[ghost]

You should be change path in build.sh. From /home/build/awx-rpm-build/awx-rpm to $PWD, so is dynamic.