script_dir = os.path.dirname(__file__)
file_path = os.path.join(script_dir, 'config.yaml')

with open(file_path, 'r') as stream:
    index = 'two'
    load = yaml.load(stream)
    USER = load[index]['USER']
    PASS = load[index]['PASS']
    HOST = load[index]['HOST']
    PORT = load[index]['PORT']
    ...

one:
  USER: "john"
  PASS: "qwerty"
  HOST: "127.0.0.1"
  PORT: "20"
two:
  USER: "jane"
  PASS: "qwerty"
  HOST: "196.162.0.1"
  PORT: "80"

import yaml
import os

script_dir = os.path.dirname(__file__)
file_path = os.path.join(script_dir, 'config.yaml')

index = 'two'

with open(file_path, 'r') as stream:
    load = yaml.safe_load(stream)

for key in load[index]:
    globals()[key] = load[index][key]

print(USER)
print(PORT)