1. Load VLAN configuration
config load /home/admin/sonic_vlan_config_test.json
{
    "VLAN": {
        "Vlan1000": {
            "dhcp_servers": [
                "192.0.0.1",
                "192.0.0.2",
                "192.0.0.3",
                "192.0.0.4"
            ],
            "members": [
                "Ethernet60",
                "Ethernet64"
            ],
            "vlanid": "1000"
        },
        "Vlan2000": {
            "dhcp_servers": [
                "192.1.0.1",
                "192.1.0.2",
                "192.1.0.3",
                "192.1.0.4"
            ],
            "members": [
                "Ethernet68"
            ],
            "vlanid": "2000"
        }
    },
    "VLAN_MEMBER": {
        "Vlan1000|Ethernet60": {
            "tagging_mode": "untagged"
        },
        "Vlan1000|Ethernet64": {
            "tagging_mode": "untagged"
        },
        "Vlan2000|Ethernet68": {
            "tagging_mode": "tagged"
        }
    }
}

2. config load will call below command to do render

usage: sonic-cfggen [-h] [-m [MINIGRAPH] | -M DEVICE_DESCRIPTION]
                    [-p PORT_CONFIG] [-y YAML] [-j JSON] [-a ADDITIONAL_DATA]
                    [-d] [-H] [-s REDIS_UNIX_SOCK_FILE]
                    [-t TEMPLATE | -v VAR | --var-json VAR_JSON | --write-to-db]