ncsa-htcdaskgateway 1.0.0rc1

Launches a Dask Gateway cluster in K8s and joins HTCondor workers to it

NCSA HTCdaskGateway

Subclasses the Dask Gateway client to launch dask clusters in Kubernetes, but with HTCondor workers. This is a fork of the ingenious original idea by Maria Acosta at Fermilab as part of their Elastic Analysis Facility project.

How it Works

This is a drop-in replacement for the official Dask Gateway client. It keeps the same authentication and interaction with the gateway server (which is assumed to be running in a Kubernetes cluster). When the user requests a new cluster, this client communicates with the gateway server and instructs it to launch a cluster. We are running a modified docker image in the cluster which only launches the scheduler, and assumes that HTC workers will evetually join.

The client then uses the user's credentials to build an HTC Job file and submits it to the cluster. These jobs run the dask worker and have the necessary certs to present themselves to the scheduler.

The scheduler then accepts them into the cluster and we are ready to compute

• A Dask Gateway client extension for heterogeneous cluster mode combining the Kubernetes backend for pain-free scheduler networking, with COFFEA-powered HTCondor workers and/or OKD [coming soon].
• Latest is installed by default and deployed to the COFFEA-DASK notebook on EAF (https://analytics-hub.fnal.gov). A few lines will get you going!
• The current image for workers/schedulers is: coffeateam/coffea-dask-cc7-gateway:0.7.12-fastjet-3.3.4.0rc9-g8a990fa

Basic usage @ Fermilab EAF

• Make sure the notebook launched supports this functionality (COFFEA-DASK notebook)

from htcdaskgateway import HTCGateway

gateway = HTCGateway()
cluster = gateway.new_cluster()
cluster

# Scale my cluster to 5 HTCondor workers
cluster.scale(5)

# Obtain a client for connecting to your cluster scheduler
# Your cluster should be ready to take requests
client = cluster.get_client()
client

# When computations are finished, shutdown the cluster
cluster.shutdown()

Other functions worth checking out

• This is a multi-tenant environment, and you are authenticated via JupyterHub Oauth which means that you can create as many* clusters as you wish
• To list your clusters:

# Verify that the gateway is responding to requests by asking to list all its clusters
clusters = gateway.list_clusters()
clusters

• To connect to a specific cluster from the list:

cluster = gateway.connect(cluster_name)
cluster
cluster.shutdown()

• To gracefully close the cluster and remove HTCondor worker jobs associated to it:

cluster.shutdown()

• There are widgets implemented by Dask Gateway. Make sure to give them a try from your EAF COFFEA notebook, just execute the client and cluster commands (after properly initializing them) in a cell like:

-------------
cluster = gateway.new_cluster()
cluster
< Widget will appear after this step>
-------------
client = cluster.get_client()
client
< Widget will appear after this step >
-------------
cluster
< Widget will appear after this step >