如何使用云功能通过签名下载地址删除存储图像？

Posted 2023-02-22

【中文标题】如何使用云功能通过签名下载地址删除存储图像？

【英文标题】：How to use cloud functions to delete a storage image by signed download url?

【发布时间】：2018-06-17 17:19:39

【问题描述】：

我正在使用 firebase 云功能来生成缩略图并将签名的图像 url 存储在 firestore 中：

'use strict';

const functions = require('firebase-functions');
const mkdirp = require('mkdirp-promise');
const gcs = require('@google-cloud/storage')(keyFilename: 'service-account-credentials.json');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);
const spawn = require('child-process-promise').spawn;
const path = require('path');
const os = require('os');
const fs = require('fs');

const THUMB_MAX_HEIGHT = 200;
const THUMB_MAX_WIDTH = 200;
const THUMB_PREFIX = 'thumb_';

exports.onUploadImage = functions.storage.object().onChange(async event => 
    const filePath = event.data.name;
    const contentType = event.data.contentType;
    const fileDir = path.dirname(filePath);
    const fileName = path.basename(filePath);
    const thumbFilePath = path.normalize(path.join(fileDir, `$THUMB_PREFIX$fileName`));
    const tempLocalFile = path.join(os.tmpdir(), filePath);
    const tempLocalDir = path.dirname(tempLocalFile);
    const tempLocalThumbFile = path.join(os.tmpdir(), thumbFilePath);

    if (!contentType.startsWith('image/')) 
        return null;
    
    if (fileName.startsWith(THUMB_PREFIX)) 
        return null;
    
    if (event.data.resourceState === 'not_exists') 
        return null;
    

    const tankId = event.data.metadata.tankId;
    const userId = event.data.metadata.userId;
    const imageType = event.data.metadata.type;

    const bucket = gcs.bucket(event.data.bucket);
    const file = bucket.file(filePath);
    const thumbFile = bucket.file(thumbFilePath);
    
    const metadata = 
        contentType: contentType,
        customMetadata: 
            'type': imageType
        
    ;

    try 
        await mkdirp(tempLocalDir); 
        await file.download(destination: tempLocalFile); 
        await spawn('convert', [tempLocalFile, '-thumbnail', `$THUMB_MAX_WIDTHx$THUMB_MAX_HEIGHT>`, tempLocalThumbFile], capture: ['stdout', 'stderr']);
        await bucket.upload(tempLocalThumbFile,  destination: thumbFilePath, metadata: metadata );
        await fs.unlinkSync(tempLocalFile);
        await fs.unlinkSync(tempLocalThumbFile);

        const config = 
            action: 'read',
            expires: '03-01-2500'
        ;

        const results = await Promise.all([
            thumbFile.getSignedUrl(config),
            file.getSignedUrl(config)
        ]);

        const thumbResult = results[0];
        const originalResult = results[1];
        const thumbFileUrl = thumbResult[0];
        const fileUrl = originalResult[0];

        const tankRef = admin.firestore().collection('tanks').doc(tankId);

        switch(imageType) 
            case 'gallery':
                await tankRef
                    .collection('gallery')
                    .add(
                        url: fileUrl,
                        thumbnail: thumbFileUrl,
                        createdAt: new Date()
                    );

                const tankSnapshot = await tankRef.get();
                const tankData = await tankSnapshot.data();

                let galleryCount = tankData.galleryCount || 0;
                galleryCount += 1;

                if (galleryCount < 0) galleryCount = 0;

                return await tankRef.update( galleryCount ,  merge: true );
            case 'tankImage':
                await tankRef.set( image: fileUrl, image_thumb: thumbFileUrl ,  merge: true );
                return null;
            case 'profileImage':
                await admin.auth().updateUser(userId,  photoURL: thumbFileUrl );
                await admin.firestore()
                    .collection('users')
                    .doc(userId)
                    .set(image: fileUrl);
                return null;
            default:
                return null
        
    
    catch(err) 
        console.log(err);
    
);

现在我正在尝试编写另一个云函数，当 firestore db 条目被删除时，它会从存储桶中删除存储的文件：

exports.onGalleryImageDelete = functions.firestore
    .document('/tanks/tankId/gallery/docId')
    .onDelete(async event => 
        const deletedDoc = event.data.previous.data();
        const bucket = admin.storage().bucket();

        await bucket.file(deletedDoc.url).delete();  // this is wrong... no idea how to solve this
        await bucket.file(deletedDoc.thumbnail).delete();

        return await updateTankDocumentCounter(event, 'galleryCount', 'onDelete');
    );

此代码实际上不起作用并返回一些 API 错误。如何从给定的签名下载 url 中删除这些图像？

【问题讨论】：

您可以在存储中存储路径以及签名的 url。签名的 url 不会帮助您删除文件，但存储路径会。 filePath 和 thumbFilePath.

非常感谢。我已经想到了这一点，但确实希望有更好的解决方案。

【参考方案1】：

根据 Doug Stevenson 的评论，我存储了数据库的路径并最终得到了这个云功能：

exports.onGalleryImageDelete = functions.firestore
    .document('/tanks/tankId/gallery/docId')
    .onDelete(async event => 
        const deletedDoc = event.data.previous.data();
        const filePath = deletedDoc.path;
        const fileDir = path.dirname(filePath);
        const fileName = path.basename(filePath);
        const thumbFilePath = path.normalize(path.join(fileDir, `$THUMB_PREFIX$fileName`));

        const bucket = admin.storage().bucket();

        return await Promise.all([
            await bucket.file(filePath).delete(),
            await bucket.file(thumbFilePath).delete(),
            updateTankDocumentCounter(event, 'galleryCount', 'onDelete')
        ]);
    );

【参考方案2】：

我也遇到了这个问题。结果返回一个存储所有隐藏信息的文档。 如果 Firebase 有什么好的，其他的就很差了。