公共 GC 存储访问失败，匿名调用者没有 storage.objects.get 访问权限

Question

I'm trying to access Sentinel2 public data as described here: https://cloud.google.com/storage/docs/public-datasets

That document says: "By contrast, accessing public data with a Cloud Storage API link does not require authentication."

However I'm getting the following error: "com.google.cloud.storage.StorageException: Anonymous caller does not have storage.objects.get access to the Google Cloud Storage object." I'm using Java API:

storage = StorageOptions.getDefaultInstance().getService()

blob = storage.get(BlobId.of("bucketName", "objectName"))

Does anyone know how to download those files using Java API? Thanks!

Answer 1

The object needs to be publicly readable in order to access it anonymously, and that error indicates the object you're trying to read is not publicly readable.

Answer 2

The Sentinel-2 bucket, gcp-public-data-sentinel-2 , does not allow unauthenticated, anonymous listing (although you should be able to browse it while logged in as any account). Instead, the object index.csv.gz inside the bucket contains a listing of the contents which you may access. Individual objects can be downloaded anonymously and have a fairly lengthy file path, for example:

https://storage.googleapis.com/gcp-public-data-sentinel-2/tiles/04/E/CR/S2B_MSIL1C_20190301T202209_N0207_R042_T04ECR_20190301T212521.SAFE/GRANULE/L1C_T04ECR_A010364_20190301T202210/IMG_DATA/T04ECR_20190301T202209_B01.jp2