Add a mutex to prevent reacing accounts updates from multiple
simultaneous account update requests.
This mutex will help with racing updates to the IAM data
from multiple requests to this gateway instance, but
will not help with racing updates to multiple load balanced
gateway instances. This is a limitation of the internal
IAM service. All account updates should be sent to a single
gateway instance if possible.
There were a couple of cases where parsing the stored IAM info
could return a config with a nil map that would panic in a
future assignment. So we just need to make sure there is an
initialized map when we return the config with no error set.
Use Vault as an IAM service. This is intended to be managed through
the versitygw admin commands similar to the internal iam service.
This uses the kv-v2 key/value secrets storage, and uses access key
for the key and stores the JSON serialized account data as the value.
This currently only supports roleid/rolesecret or root token
authentication methods to Vault.
The intent was to have a project id that could be set along with
user and group ids for new files/objects in the backend. However,
most filesystems don't actually associate a project with a user,
and instead have the project id inherited from parent directories.
Let's remove the project id for now, and we can always bring it
back if we have a backend that will be able to make use of it.
