gcsfuse Input/Output error

Question

I'm getting an Input/Output error when I try and create a directory or file in a google cloud storage bucket mounted on a linux (Ubuntu 15.10) directory.

Steps I have done:

• Created a user named transfer
• Created a /mnt/backups directory and ran chown -R transfer /mnt/backups
• As the user transfer, ran gcsfuse --implicit-dir backup01-bucket /mnt/backups. The file system mounts successfully
• Run mkdir test and get the error mkdir: cannot create directory test: Input/output error

Is there something I missed? What I'm trying to do is be able to ftp files to the server and store them in the google storeage bucket rather than local storage.

Update I modified the command to get some debug information:

gcsfuse --implicit-dirs --foreground --debug_gcs --debug_fuse backup01-bucket /mnt/backups

Then ran mkdir /mnt/backups/test as the transfer user.

The following bedug information came out:

fuse_debug: Op 0x00000060        connection.go:395] <- GetInodeAttributes (inode 1)
fuse_debug: Op 0x00000060        connection.go:474] -> OK
fuse_debug: Op 0x00000061        connection.go:395] <- LookUpInode (parent 1, name "test")
gcs: Req             0x3a: <- StatObject("test/")
gcs: Req             0x3b: <- ListObjects()
gcs: Req             0x3c: <- StatObject("test")
gcs: Req             0x3c: -> StatObject("test") (53.375107ms): gcs.NotFoundError: googleapi: Error 404: Not Found, notFound
gcs: Req             0x3b: -> ListObjects() (59.061271ms): OK
gcs: Req             0x3a: -> StatObject("test/") (71.666112ms): gcs.NotFoundError: googleapi: Error 404: Not Found, notFound
fuse_debug: Op 0x00000061        connection.go:476] -> Error: "no such file or directory"
fuse_debug: Op 0x00000062        connection.go:395] <- MkDir
gcs: Req             0x3d: <- CreateObject("test/")
gcs: Req             0x3d: -> CreateObject("test/") (22.090155ms): googleapi: Error 403: Insufficient Permission, insufficientPermissions
fuse_debug: Op 0x00000062        connection.go:476] -> Error: "CreateChildDir: googleapi: Error 403: Insufficient Permission, insufficientPermissions"
fuse: 2016/04/04 06:51:02.922866 *fuseops.MkDirOp error: CreateChildDir: googleapi: Error 403: Insufficient Permission, insufficientPermissions
2016/04/04 06:51:08.378100 Starting a garbage collection run.
gcs: Req             0x3e: <- ListObjects()
gcs: Req             0x3e: -> ListObjects() (54.901164ms): OK
2016/04/04 06:51:08.433405 Garbage collection succeeded after deleted 0 objects in 55.248203ms.

Note: If I create a directory in the web console I can see the directory fine.

Answer 1

It appears from the Insufficient Permission errors in your debug output that gcsfuse doesn't have sufficient permissions to your bucket. Probably it has read-only access.

Be sure to read the credentials documentation for gcsfuse. In particular, if you're using a service account on a GCE VM make sure to set up the VM with the storage-full access scope.

Answer 2

You problem does stem from insufficient permissions, but you do not need to destroy and re-create the VM with a different scope to solve this problem. Here is another approach that is more suitable for production systems:

1. Create a service account
2. Create a key for the service account, and download the JSON file
3. Grant an appropriate role to the service account
4. Grant the appropriate permissions to the service account on the bucket
5. Upload the JSON credentials for the service account to the VM

Finally, define an environment variable that contains the path to the service account credentials when calling gcsfuse from the command line:

GOOGLE_APPLICATION_CREDENTIALS=/root/credentials/service_credential_file.json gcsfuse bucket_name /my/mount/point

Use the key_file option to accomplish the same thing in fstab. Both of these options are documented in the gcsfuse credentials documentation. (EDIT: this option is documented, but won't work for me.)

Interestingly, you need to use the environment variable or key_file option even if you have configured the service account on the VM using:

gcloud auth activate-service-account --key-file /root/credentials/service_credential_file.json

For some reason, gcsfuse ignores the active credentialed account.

Using the storage-full scope when creating a VM has security and stability implications, because it allows that VM to have full access to every bucket that belongs to the same project. Should your file storage server really be able to over-write the logs in a logging bucket, or read the database backups in another bucket?