[minigraph][port_config] Consume port_config.json while loading minigraph

[Blueve]

What I did

The port state will be reset to up if user use config load_minigraph to recover configurations.
This PR is for supporting consume port_config.json while loading minigraph. User can put the stateful port_config.json with minigraph file to keep the port state unchanged after reload minigraph.
The port_config.json includes a segment of config_db PORT table(we called that segment configlet as well) and it will be placed on \etc\sonic\port_config.json, below is a sample:

[
  {
    "PORT": {
      "Ethernet112": {
        "admin_status": "down"
      },
      "Ethernet116": {
        "admin_status": "up"
      }
    }
  }
]

This feature will only consume the port_config.json when the file is existed in \etc\sonic\port_config.json.

Please notice that we do not leverage this feature #716 to consume the port_config.json due to the configlet might contains multiple fields for an interface such as mtu, speed, ... however, we just want to consume the admin_status here only and there might have some side effects if we update the PORT table only.

How I did it

Add code config load_minigraph command to let it consume port_config.json.

How to verify it

Add UTs.

tests/config_test.py::TestLoadMinigraph::test_load_minigraph_with_port_config_bad_format PASSED [ 15%]
tests/config_test.py::TestLoadMinigraph::test_load_minigraph_with_port_config_inconsistent_port PASSED [ 16%]
tests/config_test.py::TestLoadMinigraph::test_load_minigraph_with_port_config PASSED [ 16%]

KVM SONiC test:
Before

admin@vlab-01:/etc/sonic$ show interface status
      Interface            Lanes    Speed    MTU    FEC           Alias             Vlan    Oper    Admin    Type    Asym PFC
---------------  ---------------  -------  -----  -----  --------------  ---------------  ------  -------  ------  ----------
    Ethernet112      93,94,95,96      40G   9100    N/A  fortyGigE0/112  PortChannel0001      up       up     N/A         off
    Ethernet116      89,90,91,92      40G   9100    N/A  fortyGigE0/116  PortChannel0002      up       up     N/A         off
    Ethernet120  101,102,103,104      40G   9100    N/A  fortyGigE0/120  PortChannel0003      up       up     N/A         off
    Ethernet124     97,98,99,100      40G   9100    N/A  fortyGigE0/124  PortChannel0004      up       up     N/A         off

admin@vlab-01:/etc/sonic$ show ip bgp sum
Neighbhor      V     AS    MsgRcvd    MsgSent    TblVer    InQ    OutQ  Up/Down      State/PfxRcd  NeighborName
-----------  ---  -----  ---------  ---------  --------  -----  ------  ---------  --------------  --------------
10.0.0.57      4  64600      22731      24480         0      0       0  16:16:49             6400  ARISTA01T1
10.0.0.59      4  64600      22752      24480         0      0       0  16:16:48             6400  ARISTA02T1
10.0.0.61      4  64600      22744      24480         0      0       0  16:16:48             6400  ARISTA03T1
10.0.0.63      4  64600      22736      24480         0      0       0  16:16:48             6400  ARISTA04T1

Total number of neighbors 4

Prepare port_config.json with below content:

[
  {
    "PORT": {
      "Ethernet112": {
        "admin_status": "down"
      },
      "Ethernet116": {
        "admin_status": "up"
      }
    }
  }
]

After config load_minigraph:

admin@vlab-01:/etc/sonic$ show interface status
      Interface            Lanes    Speed    MTU    FEC           Alias             Vlan    Oper    Admin    Type    Asym PFC
---------------  ---------------  -------  -----  -----  --------------  ---------------  ------  -------  ------  ----------
    Ethernet112      93,94,95,96      40G   9100    N/A  fortyGigE0/112  PortChannel0001    down     down     N/A         off
    Ethernet116      89,90,91,92      40G   9100    N/A  fortyGigE0/116  PortChannel0002      up       up     N/A         off
    Ethernet120  101,102,103,104      40G   9100    N/A  fortyGigE0/120  PortChannel0003      up       up     N/A         off
    Ethernet124     97,98,99,100      40G   9100    N/A  fortyGigE0/124  PortChannel0004      up       up     N/A         off

admin@vlab-01:/etc/sonic$ show ip bgp sum
Neighbhor      V     AS    MsgRcvd    MsgSent    TblVer    InQ    OutQ  Up/Down    State/PfxRcd    NeighborName
-----------  ---  -----  ---------  ---------  --------  -----  ------  ---------  --------------  --------------
10.0.0.57      4  64600          0          0         0      0       0  never      Active          ARISTA01T1
10.0.0.59      4  64600       3222       7664         0      0       0  00:00:59   6400            ARISTA02T1
10.0.0.61      4  64600       3223       7664         0      0       0  00:00:58   6400            ARISTA03T1
10.0.0.63      4  64600       3222       7664         0      0       0  00:00:59   6400            ARISTA04T1

Remove port_config.json and run config load_minigraph again:

admin@vlab-01:/etc/sonic$ show interface status
      Interface            Lanes    Speed    MTU    FEC           Alias             Vlan    Oper    Admin    Type    Asym PFC
---------------  ---------------  -------  -----  -----  --------------  ---------------  ------  -------  ------  ----------
    Ethernet112      93,94,95,96      40G   9100    N/A  fortyGigE0/112  PortChannel0001      up       up     N/A         off
    Ethernet116      89,90,91,92      40G   9100    N/A  fortyGigE0/116  PortChannel0002      up       up     N/A         off
    Ethernet120  101,102,103,104      40G   9100    N/A  fortyGigE0/120  PortChannel0003      up       up     N/A         off
    Ethernet124     97,98,99,100      40G   9100    N/A  fortyGigE0/124  PortChannel0004      up       up     N/A         off

admin@vlab-01:/etc/sonic$ show ip bgp sum
Neighbhor      V     AS    MsgRcvd    MsgSent    TblVer    InQ    OutQ  Up/Down      State/PfxRcd  NeighborName
-----------  ---  -----  ---------  ---------  --------  -----  ------  ---------  --------------  --------------
10.0.0.57      4  64600       3274       8396         0      0       0  00:03:30             6400  ARISTA01T1
10.0.0.59      4  64600       3274      13103         0      0       0  00:03:31             6400  ARISTA02T1
10.0.0.61      4  64600       3274      13104         0      0       0  00:03:31             6400  ARISTA03T1
10.0.0.63      4  64600       4884       9839         0      0       0  00:03:18             6400  ARISTA04T1

Total number of neighbors 4

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

N/A

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

N/A

[lguohan]

the pr failed unit test on 202012 branch, thus reverted on 202012 branch. @Blueve , can you make sure it is tested on previous branches?

[Blueve]

Consider there is a known incompatible issue, I removed release branch tags for now.

[abdosi]

why is this needed for 201911 ? is there any use-case for this ?

[Blueve]

why is this needed for 201911 ? is there any use-case for this ?

This is a method for keeping port state unchanged after reload minigraph.
You know, the port state will be set to UP by default after load minigraph, which is unexpected in some case.