serve_thumb.py

import json
import boto3
from bs4 import BeautifulSoup
from PIL import Image
from io import BytesIO


def get_image_name(html_body):
    body = BeautifulSoup(html_body, "html.parser")
    image_tag = body.find("meta", property="og:image")
    image_name = image_tag["content"].split("/")[-1]
    return image_name


def resize_image(image):
    sizeX = image.size[0]
    sizeY = image.size[1]
    if sizeX > 300:
        image.thumbnail((299, sizeY))


def create_thumbnail(s3_client, s3_bucket, original_image, path):
    image_object = s3_client.get_object(Bucket=s3_bucket, Key=original_image)
    image = Image.open(BytesIO(image_object["Body"].read()))
    resize_image(image)
    file_object = BytesIO()
    image.save(file_object, "png")
    file_object.seek(0)
    s3_client.put_object(
        Body=file_object,
        Bucket=s3_bucket,
        Key=path,
        ContentType=image_object["ContentType"],
    )


def object_exists(s3_client, s3_bucket, path):
    try:
        s3_client.head_object(Bucket=s3_bucket, Key=path)
        return True
    except:
        return False


def lambda_handler(event, context):

    request = event["Records"][0]["cf"]["request"]

    if "api/rich_link" in request["uri"]:
        s3_bucket = "cambiatus-uploads"
        s3_image_path = "cambiatus-uploads/"
        s3_thumb_path = "cambiatus-uploads/thumbnails/"
        s3_client = boto3.client("s3")

        image_name = get_image_name(request["body"])

        if not object_exists(s3_client, s3_bucket, s3_thumb_path + image_name):
            create_thumbnail(
                s3_client,
                s3_bucket,
                s3_image_path + image_name,
                s3_thumb_path + image_name,
            )

        request["body"] = request["body"].replace(s3_image_path, s3_thumb_path)

    return {"statusCode": 200, "body": json.dumps(request["body"])}