Prevent shutdown/startup commands on invalid interface names "fixes (SONiC/issues/268)"

[kirankella]

- What I did
Invalid interface names are pushed into the CONFIG DB though they don't have a valid alias name, due to a missing check in shutdown/startup functions.
Later show commands that check for alias names on the interfaces fail.

- How I did it
In the main.py utilities script, check if the given interface name exists in the PORT_TABLE in config db. If not, fail the shutdown/startup functions there throwing an error to the user prompting for a valid interface name.

- How to verify it
Issue shutdown or startup commands on invalid interface names, followed by show interfaces status.

- Previous command output (if the output of a command-line utility has changed)

root@sonic-testing:/home/admin# config interface Ethernet99 shutdown
root@sonic-testing:/home/admin# show interface status
Traceback (most recent call last):
File "/usr/bin/show", line 9, in
load_entry_point('sonic-utilities==1.2', 'console_scripts', 'show')()
File "/usr/lib/python2.7/dist-packages/pkg_resources/init.py", line 561, in load_entry_point
return get_distribution(dist).load_entry_point(group, name)
File "/usr/lib/python2.7/dist-packages/pkg_resources/init.py", line 2631, in load_entry_point
return ep.load()
File "/usr/lib/python2.7/dist-packages/pkg_resources/init.py", line 2291, in load
return self.resolve()
File "/usr/lib/python2.7/dist-packages/pkg_resources/init.py", line 2297, in resolve
module = import(self.module_name, fromlist=['name'], level=0)
File "/usr/lib/python2.7/dist-packages/show/main.py", line 193, in
iface_alias_converter = InterfaceAliasConverter()
File "/usr/lib/python2.7/dist-packages/show/main.py", line 58, in init
self.port_dict[port_name]['alias']):
KeyError: 'alias'

- New command output (if the output of a command-line utility has changed)

root@sonic:/home/admin# config interface Ethernet99 shutdown
Usage: config interface shutdown [OPTIONS]

Error: Enter valid interface name!!

root@sonic:/home/admin# show interface status
Interface Lanes Speed MTU Alias Oper Admin Type

---

Ethernet0 13 N/A 9100 tenGigE0 down up SFP
Ethernet1 14 N/A 9100 tenGigE1 down up N/A
Ethernet2 15 N/A 9100 tenGigE2 down up SFP
....
-->

[msftclas]

All CLA requirements met.

[leoli-nps]

Hi kirankella, with your changes, I have another problem. When I use the command “sudo config interface PortChannel0001 shutdown”, the terminal prompts that the interface name is invalid, as shown below:
admin@sonic:~$ sudo config interface PortChannel0001 shutdown
Usage: config interface shutdown [OPTIONS]

Error: Interface name is invalid. Please enter a valid interface name!!
admin@sonic:~$ show interfaces portchannel
Flags: A - active, I - inactive, Up - up, Dw - Down, N/A - not available, S - selected, D - deselected
No. Team Dev Protocol Ports

---

0001 PortChannel0001 LACP(A)(Up) Ethernet108(S)
admin@sonic:~$

So, when checking the validity of the interface name, should it also include the PORTCHANNEL table, not just in the PORT table?
@kirankella

[kirankella]

Hi kirankella, with your changes, I have another problem. When I use the command “sudo config interface PortChannel0001 shutdown”, the terminal prompts that the interface name is invalid, as shown below:
admin@sonic:~$ sudo config interface PortChannel0001 shutdown
Usage: config interface shutdown [OPTIONS]

Error: Interface name is invalid. Please enter a valid interface name!!
admin@sonic:~$ show interfaces portchannel
Flags: A - active, I - inactive, Up - up, Dw - Down, N/A - not available, S - selected, D - deselected
No. Team Dev Protocol Ports

0001 PortChannel0001 LACP(A)(Up) Ethernet108(S)
admin@sonic:~$

So, when checking the validity of the interface name, should it also include the PORTCHANNEL table, not just in the PORT table?
@kirankella

@leoli-nps You are right. We should be checking the PORTCHANNEL table as well. Raised PR #474 to fix the same.