阿里云 Serverless 图片处理实验（缩略图 + 水印）

# -*- coding: utf-8 -*-
import oss2
from PIL import Image, ImageDraw, ImageFont
import io
import os
import traceback

# ===================== OSS 配置（通过环境变量设置） =====================
OSS_ENDPOINT = os.environ.get('OSS_ENDPOINT')
OSS_ACCESS_KEY_ID = os.environ.get('OSS_ACCESS_KEY_ID')
OSS_ACCESS_KEY_SECRET = os.environ.get('OSS_ACCESS_KEY_SECRET')
OSS_BUCKET_NAME = os.environ.get('OSS_BUCKET_NAME', 'image-bucket')

ORIGINAL_FOLDER = 'original/'
PROCESSED_FOLDER = 'processed/'

# ====== 核心判空 ======
if not all([OSS_ENDPOINT, OSS_ACCESS_KEY_ID, OSS_ACCESS_KEY_SECRET, OSS_BUCKET_NAME]):
    raise RuntimeError("OSS 配置未完整设置，请检查环境变量")

# 初始化 OSS 客户端
auth = oss2.Auth(OSS_ACCESS_KEY_ID, OSS_ACCESS_KEY_SECRET)
bucket = oss2.Bucket(auth, OSS_ENDPOINT, OSS_BUCKET_NAME)

# ====== 主函数 ======
def handler(event, context):
    if 'events' not in event:
        print("非 OSS 触发事件")
        return {"statusCode": 400, "body": "非 OSS 触发事件"}

    for record in event['events']:
        key = record['oss']['object']['key']
        print(f"触发处理的 Key: {key}")  # 调试日志

        # ====== 只处理 original/ 文件夹 ======
        if not key.startswith(ORIGINAL_FOLDER):
            print(f"跳过非 original/ 目录的文件: {key}")
            continue

        try:
            # 下载 OSS 对象
            obj = bucket.get_object(key)
            image_data = obj.read()

            # ====== 尝试打开图片，非图片跳过 ======
            try:
                img = Image.open(io.BytesIO(image_data))
            except Exception:
                print(f"非图片文件，跳过: {key}")
                continue

            print(f"原图大小: {img.size}, 模式: {img.mode}")

            # ====== 生成缩略图 ======
            img.thumbnail((200, 200), Image.ANTIALIAS)

            # ====== 透明 PNG 转换处理 ======
            if img.mode in ('RGBA', 'LA') or (img.mode == 'P' and 'transparency' in img.info):
                background = Image.new("RGB", img.size, (255, 255, 255))  # 白底
                background.paste(img, mask=img.split()[-1])  # 保留透明部分
                img = background
            elif img.mode != 'RGB':
                img = img.convert('RGB')

            # ====== 添加水印 ======
            draw = ImageDraw.Draw(img)
            text = "Serverless"
            try:
                font = ImageFont.truetype("/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf", 20)
            except Exception:
                font = ImageFont.load_default()
            text_width, text_height = draw.textsize(text, font=font)
            draw.text((img.width - text_width - 10, img.height - text_height - 10),
                      text, fill=(255, 0, 0), font=font)

            # ====== 保存到内存并写回 OSS ======
            out_buffer = io.BytesIO()
            img.save(out_buffer, format='JPEG')
            out_buffer.seek(0)

            filename = key.split('/')[-1]
            processed_key = f"{PROCESSED_FOLDER}thumb_{filename}"
            bucket.put_object(processed_key, out_buffer)
            print(f"生成文件成功: {processed_key}")

        except Exception as e:
            print(f"处理 {key} 失败: {e}")
            traceback.print_exc()  # 打印详细堆栈
            continue

    return {"statusCode": 200, "body": "处理完成"}