Unable to fix CORS policy on Google Cloud storage

Question

I am trying to upload files to Google cloud storage's bucket from a React app. I have enabled CORS setting for the bucket but it seems that I cannot still get access from the web app. I am getting the following error:

Access to fetch at 'https://storage.googleapis.com/my_unique_bucket/ABCdio%20Vi?GoogleAccessId=storage-ucardia%40ucardia-297520.iam.gserviceaccount.com&Expires=1612456695&Signature=oxb2LVj22hc4%2FsnskKIwaq%2BK9qq88yAmnAGN1pbRJ%2BPJ2d68%2BHRRBYS24xPNwBLSkVktsjSWTBBoWv5tTkCuUAzG3Q2Q51gLdoaLUmFyGt8a4hgKJ94DeTaAJL0Hf0rwz0sNx6SkSdqrrQF%2BGlRH4HYI10JBQHuw3%2BQMPIW%2FRXTlfcvjdCkdRT9vX6twjBrC4bdIijvB31SvxbipQHWuhh6QjlKtybp3OW8kV2tY00KNWv0pE98%2FCRDBikzVkyZwM8WOYEXWUuxY9lem9LYjkBo%2BafQECApvkTQVjg%2FWJo%2BUCTVpnO5wKL58BN2QCqkmG%2FIPAwg0ptQJVMcxFhfCZw%3D%3D' from origin 'https://dashboard-fe.uc.r.appspot.com' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.

The CORS setting in JSON file is following:

[]

However, I has tried with the setting specifying the web URL and PUT method in the JSON as well, but didn't work.

UPDATE 1:

Node.js API:

const storage = new Storage({
    keyFilename: path.join(__dirname, '../../../projectId.json'),
    projectId: 'projectId',
});

storage.getBuckets().then((x) => {
    console.log(x);
});

const generateSignedUrl = async (req, res) => {
    const { filename, filetype } = req.query;
    // These options will allow temporary read access to the file
    const options = {
        version: 'v2', // defaults to 'v2' if missing.
        action: 'write',
        expires: Date.now() + 1000 * 60 * 60, // one hour
        contentType: 'application/x-www-form-urlencoded',
    };

    try {
        // Get a v2 signed URL for the file
        const [url] = await storage.bucket('my_unique_bucket').file(filename).getSignedUrl(options);

        res.status(ok).json({ data: url, message: GENERATE_SIGNED_URL_SUCCESS, status: true });
    } catch (error) {
        res.status(internalServerError).json({ error, status: false, message: GENERATE_SIGNED_URL_FAILED });
    }
};

Reactjs Client:

export const putFile = async ({ url, file }) => {
    const method = 'PUT';

    return await fetch(`${url}`, {
        body: file,
        method,
        headers: {
            // Accept: file.type,
            'Content-Type': file.type,
            'Access-Control-Allow-Origin': '*',
        },
    });
};

UPDATE 2: This link says that it is an issue with the formation of the URL but I am getting the URL as presigned URL from the google cloud storage NPM package. BTW I have followed this link to set up the mechanism but it seems I am missing something very obvious.

Answer 1

Sorry for the delay in my response. I noticed something curious in your code. You have this configuration in your JSON file

[]

However, in your react client you have this

headers: {
            // Accept: file.type,
            'Content-Type': file.type,
            'Access-Control-Allow-Origin': '*',
        }

If you have [] in your JSON file, you are removing CORS from a bucket. Nevertheless, you are still sending the value. You need to add this to your JSON file to set the CORS in your bucket.

[ { "origin": ["*"], "method": ["PUT"] } ]

Here you can find an article about it.