[yang]: Add yang models for table BGP_ALLOWED_PREFIXES

[StormLiangMS]

Why I did it

end2end test is blocked by Yang model for BGP allowed prefix list.

How I did it

Create new yang files for BGP allowed prefix list, and add UT.

How to verify it

Run UT for sonic-yang-models.

Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006
• 202012
• 202106
• 202111

Description for the changelog

Link to config_db schema for YANG module changes

A picture of a cute animal (not mandatory but encouraged)

Fix: #9866

[StormLiangMS]

@wen587 I verified this on master image, looks ok now, the reason is that the previous key pattern is wrong, I use "prefixs_p4", now it works.

admin@str-s6000-acs-11:$ ls
add.json verify_yang.py
admin@str-s6000-acs-11:$ cat add.json
{
"BGP_ALLOWED_PREFIXES": {
"DEPLOYMENT_ID|0": {
"prefixes_v4": [
"10.20.0.0/16"
],
"prefixes_v6": [
"fc02:20::/64"
]
}
}
}
admin@str-s6000-acs-11:$ cat verify_yang.py
import subprocess
import sonic_yang
import json
def get_config_db_json():
cmd = "show runningconfiguration all"
result = subprocess.Popen(cmd, shell=True, text=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
text, err = result.communicate()
return json.loads(text)
configDbJson = get_config_db_json()
sy = sonic_yang.SonicYang("/usr/local/yang-models")
sy.loadYangModel()
sy.loadData(configDbJson )
sy.validate_data_tree()
admin@str-s6000-acs-11:$ python3 verify_yang.py
sonic_yang(6):Note: Below table(s) have no YANG models: CONSOLE_SWITCH, CRM, DHCP_SERVER, FEATURE, KDUMP, RESTAPI, SNMP, SNMP_COMMUNITY, TELEMETRY, XCVRD_LOG
admin@str-s6000-acs-11:~$

[wen587]

LGTM. Please wait for other reviewer's approval.

[ganglyu]

Does community have any pattern? 123:123?

[StormLiangMS]

@ganglyu good catch, I found there are at least 2 different formats for community id, one is 4 bytes, the other is 2 bytes:2bytes, I took a reference from existing yang model files, all of them take string as the type of community and no pattern enforcement.
As you suggested, I think we should put a enforcement for the community id for all cases, filed an issue to track this, address this may beyond the scope of this PR.
#10145