This is an updated version of the 2018 edition
Use OpenStack swift on Jetstream for object storage
Jetstream also offers (currently in beta) access to object storage via OpenStack Swift. This is a separate service from the Jetstream Virtual Machines, so you do not need to spin any Virtual Machine dedicated to storing the data but just use the object storage already provided by Jetstream.
Read Zarr files from object store
If somebody else has already made available some files on object store and set their visibility to “public”, anybody can read them.
See the example Notebook to read Zarr files.
OpenStack Swift already provides an endpoint which has an interface compatible with Amazon S3, therefore
we can directly use the
S3FileSystem provided by
Then we can build a
S3Map object which
xarray can access.
I removed the endpoint url from the Notebook to avoid test traffic. You can request it to
the XSEDE helpdesk.
In this example I am using the
distributed scheduler on a single node, you can scale up your computation
having workers distributed on multiple nodes, just make sure that all the workers have access to the
Write Zarr files or read private files
In this case we need authentication.
First you need to ask to the XSEDE helpdesk API access to Jetstream, this also gives access to the Horizon interface, which has many advanced features that are not available in Atmosphere.
Create a bucket
Object store systems are organized on buckets, which are like root folders of our filesystem. From the Horizon interface, we can choose Object Store -> Containers (quite confusing way of referring to buckets in OpenStack). Here we can check content of existing buckets or create a new one.
From Horizon, choose the project you want to charge usage from the dropdown menu at the top.
Then download the openstack RC file version 3 from: https://iu.jetstream-cloud.org/project/api_access/
At this point we need to transform it into Amazon-style credentials, you can do this on any host, not necessarily on Jetstream, install OpenStack client:
pip install python-openstackclient
source the openstackRC file, put the password, this is the TACC password (the same used to access Horizon), NOT the XSEDE Password.
Now we can check the content of the bucket we created above:
openstack object list my_bucket
Now create ec2 credentials with:
openstack ec2 credentials create
This is going to display AWS access key and AWS secret, we can save credentials in
in the machine we want then use to write to object store.
[default] region=RegionOne aws_access_key_id=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx aws_secret_access_key=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
We can check if we can successfully login using
s3fs, notice we do not use
we did before:
import s3fs fs = s3fs.S3FileSystem(client_kwargs=dict(endpoint_url="JETSTREAM_SWIFT_ENDPOINT")) fs.ls("my_bucket")
Make sure that
JETSTREAM_SWIFT_ENDPOINT does not include
Read a file from local filesystem and write to Object store
See this notebook as an example of writing to object store,
first we make sure to have the necessary Python packages,
then we use
xarray to read data from NetCDF and then write back to Zarr first locally and then
s3fs to Openstack Swift.
See the Zarr documentation about how to tweak, compression, data transformations and chunking.