Strange error with Apache on CentOS 7

I am trying to build virtual machine using vagrant, virtualbox and CentOS 7 64bit. Host OS is Ubuntu 14.04 64bit. Vagrant is 1.9.2, VirtualBox 5.1.6.

Here is the Vagrantfile

Vagrant.configure("2") do |config|
  config.vm.box = "centos/7"
  config.vm.box_check_update = false

  # Enable cache if plugin is installed
  # To install it execute: vagrant plugin install vagrant-cachier
  # cache will be located in [thisvagrantdir]/.vagrant/machines/default/cache
  if Vagrant.has_plugin?("vagrant-cachier")
    config.cache.auto_detect = true
    config.cache.scope       = :machine
  end

  config.vm.network "private_network", ip: "192.168.33.101"

  config.hostmanager.enabled = true
  config.hostmanager.manage_host = true
  config.hostmanager.aliases = %w(centos7.dev)

  config.ssh.forward_agent = true
  config.vm.synced_folder ".", "/vagrant", type: "nfs"

  config.vm.provider "virtualbox" do |vb|
    vb.customize ["modifyvm", :id, "--memory", "2048"   ]
    vb.customize ["modifyvm", :id, "--name"  , "centos7"]
  end

  config.vm.provision "shell" do |s|
     s.privileged = true
     s.path       = "provisioner.sh"
  end

end

Now in the provisioner.sh I install PHP, some extensions and add one config file for apache located in /etc/httpd/conf.d/site.conf . Here is the site.conf:

<VirtualHost _default_:80>
     ServerAdmin webmaster@example.com
     DocumentRoot /vagrant/www/moodle
     ServerName centos7.dev
     ErrorLog /vagrant/log/error.log
     CustomLog /vagrant/log/requests.log combined

  <IfModule dir_module>
    DirectoryIndex index.php index.html
  </IfModule>

  <Directory /vagrant/www/moodle>
    Options All
    AllowOverride All
    Require all granted
  </Directory>

  <Location />
     LogLevel warn
  </Location>

</VirtualHost>

/vagrant/www/moodle is NFS attached dir from host system.

After all this is done apache just refuses to start. I can run sudo systemctl start httpd.service 100 times and nothing happens. However if I run it with sudo httpd it works???!!!

This is what I get as status

[vagrant@default ~]$ sudo systemctl status httpd.service
● httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; enabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since mar 2017-05-09 11:29:09 UTC; 8s ago
     Docs: man:httpd(8)
           man:apachectl(8)
  Process: 7149 ExecStop=/bin/kill -WINCH ${MAINPID} (code=exited, status=1/FAILURE)
  Process: 7148 ExecStart=/usr/sbin/httpd $OPTIONS -DFOREGROUND (code=exited, status=1/FAILURE)
 Main PID: 7148 (code=exited, status=1/FAILURE)

may 09 11:29:09 default systemd[1]: Starting The Apache HTTP Server...
may 09 11:29:09 default systemd[1]: httpd.service: main process exited, code=exited, status=1/FAILURE
may 09 11:29:09 default kill[7149]: kill: cannot find process ""
may 09 11:29:09 default systemd[1]: httpd.service: control process exited, code=exited status=1
may 09 11:29:09 default systemd[1]: Failed to start The Apache HTTP Server.
may 09 11:29:09 default systemd[1]: Unit httpd.service entered failed state.
may 09 11:29:09 default systemd[1]: httpd.service failed.

Any ideas as to what I'm doing wrong here? Thanks

Added content of error_log

  (13)Permission denied: AH00091: httpd: could not open error log file /vagrant/log/error.log.
  AH00015: Unable to open logs
  (13)Permission denied: AH00091: httpd: could not open error log file /vagrant/log/error.log.
  AH00015: Unable to open logs
  [Tue May 09 02:00:13.473097 2017] [core:notice] [pid 24635] SELinux policy enabled; httpd running as context unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
  [Tue May 09 02:00:13.475731 2017] [suexec:notice] [pid 24635] AH01232: suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)
  [Tue May 09 02:00:13.504866 2017] [auth_digest:notice] [pid 24636] AH01757: generating secret for digest authentication ...
  [Tue May 09 02:00:13.507336 2017] [lbmethod_heartbeat:notice] [pid 24636] AH02282: No slotmem from mod_heartmonitor
  [Tue May 09 02:00:13.536814 2017] [mpm_prefork:notice] [pid 24636] AH00163: Apache/2.4.6 (CentOS) PHP/5.4.16 configured -- resuming normal operations
  [Tue May 09 02:00:13.536867 2017] [core:notice] [pid 24636] AH00094: Command line: 'httpd'
  [Tue May 09 02:05:20.671219 2017] [mpm_prefork:notice] [pid 24636] AH00169: caught SIGTERM, shutting down
  (13)Permission denied: AH00091: httpd: could not open error log file /vagrant/log/error.log.
  AH00015: Unable to open logs
  [Tue May 09 02:07:52.571217 2017] [core:notice] [pid 6154] SELinux policy enabled; httpd running as context unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
  [Tue May 09 02:07:52.573223 2017] [suexec:notice] [pid 6154] AH01232: suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)
  [Tue May 09 02:07:52.599432 2017] [auth_digest:notice] [pid 6155] AH01757: generating secret for digest authentication ...
  [Tue May 09 02:07:52.601028 2017] [lbmethod_heartbeat:notice] [pid 6155] AH02282: No slotmem from mod_heartmonitor
  [Tue May 09 02:07:52.671389 2017] [mpm_prefork:notice] [pid 6155] AH00163: Apache/2.4.6 (CentOS) PHP/5.4.16 configured -- resuming normal operations
  [Tue May 09 02:07:52.671423 2017] [core:notice] [pid 6155] AH00094: Command line: 'httpd'
  [Tue May 09 02:20:28.697078 2017] [mpm_prefork:notice] [pid 6155] AH00169: caught SIGTERM, shutting down
  (13)Permission denied: AH00091: httpd: could not open error log file /vagrant/log/error.log.
  AH00015: Unable to open logs
  (13)Permission denied: AH00091: httpd: could not open error log file /vagrant/log/error.log.
  AH00015: Unable to open logs
  [Tue May 09 11:14:29.277789 2017] [core:notice] [pid 7361] SELinux policy enabled; httpd running as context unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
  [Tue May 09 11:14:29.285279 2017] [suexec:notice] [pid 7361] AH01232: suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)
  [Tue May 09 11:14:29.307699 2017] [auth_digest:notice] [pid 7362] AH01757: generating secret for digest authentication ...
  [Tue May 09 11:14:29.309339 2017] [lbmethod_heartbeat:notice] [pid 7362] AH02282: No slotmem from mod_heartmonitor
  [Tue May 09 11:14:29.448865 2017] [mpm_prefork:notice] [pid 7362] AH00163: Apache/2.4.6 (CentOS) PHP/5.4.16 configured -- resuming normal operations
  [Tue May 09 11:14:29.448913 2017] [core:notice] [pid 7362] AH00094: Command line: 'httpd'
  [Tue May 09 11:19:24.274215 2017] [mpm_prefork:notice] [pid 7362] AH00169: caught SIGTERM, shutting down
  (13)Permission denied: AH00091: httpd: could not open error log file /vagrant/log/error.log.
  AH00015: Unable to open logs
  (13)Permission denied: AH00091: httpd: could not open error log file /vagrant/log/error.log.
  AH00015: Unable to open logs
  (13)Permission denied: AH00091: httpd: could not open error log file /vagrant/log/error.log.
  AH00015: Unable to open logs
  (13)Permission denied: AH00091: httpd: could not open error log file /vagrant/log/error.log.
  AH00015: Unable to open logs
  (13)Permission denied: AH00091: httpd: could not open error log file /vagrant/log/error.log.
  AH00015: Unable to open logs
  [Tue May 09 11:32:03.917301 2017] [core:notice] [pid 7210] SELinux policy enabled; httpd running as context unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
  [Tue May 09 11:32:03.919728 2017] [suexec:notice] [pid 7210] AH01232: suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)
  [Tue May 09 11:32:03.944005 2017] [auth_digest:notice] [pid 7211] AH01757: generating secret for digest authentication ...
  [Tue May 09 11:32:03.945572 2017] [lbmethod_heartbeat:notice] [pid 7211] AH02282: No slotmem from mod_heartmonitor
  [Tue May 09 11:32:04.013106 2017] [mpm_prefork:notice] [pid 7211] AH00163: Apache/2.4.6 (CentOS) PHP/5.4.16 configured -- resuming normal operations
  [Tue May 09 11:32:04.013158 2017] [core:notice] [pid 7211] AH00094: Command line: 'httpd'