Refactor get_num_dpus function.

[xincunli-sonic]

Why I did it

Refactor current get_num_dpus function to consuming platform.json which is reliable way to retrieve the number of DPUs.

Work item tracking

• Microsoft ADO number:

How I did it

Read platform.json file to retrieve the number of DPU objects in DPUS section.

"DPUs": [
   {
      "DPU0": {
         "Ethernet244": "Ehternet0",
         "Ethernet248": "Ethernet1"
      }
   },
   {
      "DPU1": {
         "Ethernet252": "Ethernet0",
         "Ethernet256": "Ethernet1"
      },
   }
]

How to verify it

Create local platform json file which follow the format of hwsku.json then run the function call locally.

import json

def get_num_dpus():
    json_file = "/tmp/hwsku.json"
    if os.path.isfile(os.path.join(platform_path, "hwsku.json")):
        json_file = os.path.join(platform_path, "hwsku.json")

        try:
            with open(json_file, 'r') as file:
                platform_data = json.load(file)
        except (json.JSONDecodeError, IOError, TypeError, ValueError):
            # Handle any file reading and JSON parsing errors
            return 0

        # Convert to lower case avoid case sensitive.
        data = {k.lower(): v for k, v in platform_data.items()}
        DPUs = data.get('dpus', None)
        if DPUs is not None and len(DPUs) > 0:
            return len(DPUs)

    return 0

print(get_num_dpus()) # output is 4, which is expected.

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

• 202006
• 202012
• 202106
• 202111
• 202205
• 202211
• 202305

Tested branch (Please provide the tested image version)

Description for the changelog

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

[Pterosaur]

LGTM