Storage Signed URL gives CORS error

Google Cloud Serverless Applications
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1

Greetings again,

I am giving my client a signed url to upload files to cloud storage. However I am getting the following error when calling the URL :

Cross-Origin Resource Sharing error: PreflightMissingAllowOriginHeader

I am aware that I need to setup the server to receive the call using the header :

Access-Control-Allow-Origin

However I don’t know where to add this header to storage since the call is being made directly to storage and not to my server…

Thanx for the help !

2

Hello @icepaco33 !

Check out this documentation: Set up and view CORS configurations.

To setup the CORS configuration on a bucket, you can use the gcloud CLI. Use the following steps to set a CORS configuration on your bucket:

  1. Create a JSON file with the CORS configuration you would like to apply. Check the configuration examples for sample JSON files.

  2. Use the gcloud storage buckets update command with the –cors-file flag:

    gcloud storage buckets update gs://BUCKET_NAME --cors-file=CORS_CONFIG_FILE

To view the CORS configuration for a bucket, you can use the gcloud CLI and input the command:

gcloud storage buckets describe gs://BUCKET_NAME --format="default(cors_config)"

If the above options don’t work, you can contact Google Cloud Support to further look into your case. Let me know if it helped, thanks!

2 Likes
3

The “configuration examples” is incorrect. I got error “ERROR: ‘str’ object has no attribute ‘items’” when running the command.

The correct format is

[ { "origin": ["*"], "responseHeader": ["Content-Type"], "method": ["GET", "PUT"], "maxAgeSeconds": 3600 } ]

I found this from the gcloud storage bucket update command documentation here
https://cloud.google.com/sdk/gcloud/reference/storage/buckets/update

1 Like
4

I had the same problem and the format from pengxu is indeed correct. Here it is formatted with the example:

[
  {
    "origin": ["https://your-example-website.appspot.com"],
    "method": ["GET"],
    "responseHeader": ["Content-Type"],
    "maxAgeSeconds": 3600
  }
]