加固版本灰度发布与快速回滚：同候选分组、分层指标与版本白名单控制风险

import sys
import hashlib
import json

def compute_group(device_id, candidates, salt):
    if not device_id or not candidates:
        sys.exit(1)
    hasher = hashlib.sha256()
    hasher.update(f"{device_id}:{salt}".encode())
    digest = int.from_bytes(hasher.digest(), 'big')
    index = digest % len(candidates)
    return candidates[index]

def validate_rollback(current_version, target_version, whitelist):
    if target_version not in whitelist:
        print("ROLLBACK_FORBID: target not in whitelist")
        return False
    if target_version >= current_version:
        print("ROLLBACK_FORBID: version monotonicity violated")
        return False
    return True

if __name__ == '__main__':
    input_data = json.loads(sys.stdin.read())
    dev_id = input_data.get('device_id')
    candidates = input_data.get('candidate_versions')
    salt = input_data.get('group_salt', 'v1')
    current = input_data.get('current_version_code')
    target = input_data.get('rollback_target_code')
    wl = set(input_data.get('rollback_whitelist', []))
    if not dev_id or not candidates:
        sys.exit(1)
    group_result = compute_group(dev_id, candidates, salt)
    print(f"ASSIGNED_CANDIDATE={group_result}")
    if not validate_rollback(current, target, wl):
        sys.exit(1)