AWS Lambda文件系统权限管理与/tmp目录最佳实践

import os
import json

def lambda_handler(event, context):
    # 定义在/tmp目录下的文件路径
    temp_file_path = "/tmp/my_temp_data.txt"
    json_file_path = "/tmp/config.json"

    # 1. 写入数据到/tmp
    try:
        with open(temp_file_path, "w") as f:
            f.write("This is some temporary data written by Lambda.\n")
            f.write("It will be available for subsequent warm invocations.")
        print(f"Successfully wrote to {temp_file_path}")

        # 写入JSON文件示例
        config_data = {"setting1": "valueA", "setting2": 123}
        with open(json_file_path, "w") as f:
            json.dump(config_data, f)
        print(f"Successfully wrote JSON to {json_file_path}")

    except Exception as e:
        print(f"Error writing to /tmp: {e}")
        return {
            'statusCode': 500,
            'body': json.dumps(f'Error writing file: {e}')
        }

    # 2. 从/tmp读取数据（可以检查文件是否存在，以处理冷启动或环境回收）
    if os.path.exists(temp_file_path):
        try:
            with open(temp_file_path, "r") as f:
                content = f.read()
            print(f"Content read from {temp_file_path}:\n{content}")
        except Exception as e:
            print(f"Error reading from /tmp: {e}")
    else:
        print(f"File {temp_file_path} does not exist (possibly a cold start or environment reset).")

    if os.path.exists(json_file_path):
        try:
            with open(json_file_path, "r") as f:
                loaded_config = json.load(f)
            print(f"Loaded JSON config from {json_file_path}: {loaded_config}")
        except Exception as e:
            print(f"Error reading JSON from /tmp: {e}")

    # 3. 清理/tmp中的文件（可选，但推荐在不再需要时进行）
    # 注意：在Lambda函数结束时，文件通常会保留，直到环境被回收。
    # 如果文件较大或需要确保下次调用是干净的，可以手动删除。
    # try:
    #     if os.path.exists(temp_file_path):
    #         os.remove(temp_file_path)
    #         print(f"Cleaned up {temp_file_path}")
    #     if os.path.exists(json_file_path):
    #         os.remove(json_file_path)
    #         print(f"Cleaned up {json_file_path}")
    # except Exception as e:
    #     print(f"Error cleaning up /tmp: {e}")

    return {
        'statusCode': 200,
        'body': json.dumps('File operations completed.')
    }