Firebase Write Access for Signed Url not working

Question

I have a cloud function which will generate signed url for the uploaded file into the firebase storage and was able to generate the signed url:

const result = await Promise.all([
  storageRef.getSignedUrl({
   action: "read",
   expires
 }),
 storageRef.getSignedUrl({
  action: "write",
  expires
  })
]);

And when I tried to access the file with write access from that url via browser, below is the error message i was getting:

<Error>
<script/>
<Code>SignatureDoesNotMatch</Code>
<Message>Access denied.</Message>
<Details>The request signature we calculated does not match the signature you provided. Check your Google secret key and signing method.</Details>
<StringToSign>GET 1709282976 /mystorage.appspot.com/files/-NrBwOCgu226c7DtrgPh/7zEiXfTaen25qDzIpuy4.pdf</StringToSign>
</Error>

The read access link/token works fine, but the write access toekn does not. Is there a way to:

1. Solve this write access token
2. Create a signed url with read AND Write access in one token?

My firebase storage rules are already public so I dont know what the issue is.

Answer 1

Firstly, Firebase security rules have no effect on signed URLs. A signed URL is a GCP concept only and Firebase does not apply.

Solve this write access token

I don't see that there's anything wrong with the URL using for writing. If you load it into a browser, that will be a read action, not a write action. I would not expect a URL creating for writing would work for reading.

Create a signed url with read AND Write access in one token?

There is nothing in the documentation that suggests a single signed URL can be used for multiple types of actions. You must choose which action to allow for that URL: "read", "write", "delete", or "resumable". So, if you want to perform multiple actions, you will need a URL for each action.