Failed DHCP relay test

[tieguoevan]

Description

Steps to reproduce the issue:
Run DHCP relay test and it fails

Describe the results you received:
Test failure

and get errors in /var/log/syslog:

Sep 25 12:34:42.248407 str-s8900-54xc-01 INFO supervisord: isc-dhcp-relay Traceback (most recent call last):
Sep 25 12:34:42.248619 str-s8900-54xc-01 INFO supervisord: isc-dhcp-relay   File "/usr/local/bin/sonic-cfggen", line 215, in <module>
Sep 25 12:34:42.248728 str-s8900-54xc-01 INFO supervisord: isc-dhcp-relay     main()
Sep 25 12:34:42.248821 str-s8900-54xc-01 INFO supervisord: isc-dhcp-relay   File "/usr/local/bin/sonic-cfggen", line 200, in main
Sep 25 12:34:42.248912 str-s8900-54xc-01 INFO supervisord: isc-dhcp-relay     print template.render(data)
Sep 25 12:34:42.249054 str-s8900-54xc-01 INFO supervisord: isc-dhcp-relay   File "/usr/local/lib/python2.7/dist-packages/jinja2/environment.py", line 1008, in render
Sep 25 12:34:42.249155 str-s8900-54xc-01 INFO supervisord: isc-dhcp-relay     return self.environment.handle_exception(exc_info, True)
Sep 25 12:34:42.249248 str-s8900-54xc-01 INFO supervisord: isc-dhcp-relay   File "/usr/local/lib/python2.7/dist-packages/jinja2/environment.py", line 780, in handle_exception
Sep 25 12:34:42.249341 str-s8900-54xc-01 INFO supervisord: isc-dhcp-relay     reraise(exc_type, exc_value, tb)
Sep 25 12:34:42.249468 str-s8900-54xc-01 INFO supervisord: isc-dhcp-relay   File "<template>", line 1, in top-level template code
Sep 25 12:34:42.249577 str-s8900-54xc-01 INFO supervisord: isc-dhcp-relay   File "/usr/local/lib/python2.7/dist-packages/jinja2/environment.py", line 411, in getitem
Sep 25 12:34:42.249673 str-s8900-54xc-01 INFO supervisord: isc-dhcp-relay     return obj[argument]
Sep 25 12:34:42.249769 str-s8900-54xc-01 INFO supervisord: isc-dhcp-relay jinja2.exceptions.UndefinedError: 'minigraph_ports' is undefined

Describe the results you expected:
Test pass

Additional information you deem important (e.g. issue happens only occasionally):
It looks like the line 178 is outdated, since configDB has been introduced.
https://github.com/Azure/sonic-buildimage/blob/f570616b0dca24d0c38550e5c946e7e9bf00b342/src/isc-dhcp/isc-dhcp-4.3.1_dhcrelay-custom-circuit_id-remote_id-and-bridge-iface-support.patch#L178
Maybe it should be

+						sprintf(cmdstr, "sonic-cfggen -d -v \"PORT['%s'].alias\"", ip->name);

[jleveque]

You are correct. This line was overlooked in the transition to ConfigDB. However, I am currently working on modifications to the DHCP relay agent, and in these changes, I have created a better solution here that doesn't involve a direct call to sonic-cfggen. I expect the changes to be committed sometime this week.