Frequently asked questions¶

Additional FAQ questions are available in the GitHub discussions.

Environments¶

How are QHub conda user environments created? Who creates them?¶

The environment specifications are available in qhub_config.yml in the deployment repo, which serves to the QHub deployment using conda-store. When the user manages their environments in this way, they get all of the benefits of environment versioning that QHub does under the hood, including future features, such as convenient environment rollback and environment encapsulation in containers.

Anyone with access to the QHub deployment repo can add an environment, and there are no limits to the number of included environments.

Be careful of the YAML indentation as it differs from the conda environment.yml

What to do when the user requires `X` package and it’s not available in the environment?¶

The proper solution is to add the package to the qhub_config.yml (See #1). If they don’t have access to the deployment repo, the user needs to contact their QHub maintainer to get the required package. They can do a user install for pip packages if necessary (this is not recommended) but they won’t be available to Dask workers.

What’s included in the user environment if a user wants to use Dask?¶

The user needs to include the QHub Dask metapackage. Example: qhub-dask==0.4.1. This replaces distributed, dask, and dask-gateway with the correct pinned versions.

Why can’t a user just create their own local conda environment or edit the existing conda environments?¶

The version of conda-store used in QHub versions 0.3.11 and earlier is an alpha version. It doesn’t support using local conda environments or editing pre-exising environments directly.

See the answer to #2 for information on how to modify environments properly. In the near future, the support for user-defined environments via conda-store is going to be implemented.

How can a user install a local package? Is it available to the user’s Dask workers?¶

If the user is using a setuptools package, they can install it into their local user environment using:

pip install --no-build-isolation --user -e .

If they’re using a flit package, they can install with

flit install -s

These aren’t available to the Dask workers.

How to use .bashrc on QHub?¶

Users can use .bashrc on QHub, but it’s important to note that by default QHub sources .bash_profile. The users might need to be sure to source the .bashrc inside of the .bash_profile. It’s important to note that if they set environment variables in this way, they aren’t available inside the notebooks.

How to use environment variables on dask workers which aren’t loaded via a package?¶

It’s achieved through the UI:

import dask_gateway
gateway = dask_gateway.Gateway()
options = gateway.cluster_options()
options

It’s achieved in the same way programmatically:

env_vars = {
"ENV_1": "VALUE_1",
"ENV_2": "VALUE_2"
}
options.environment_vars = env_vars

This feature is available in release 0.3.12 or later.

What if a user can’t see the active conda environment in the terminal?¶

Set the changeps1 value in the conda config:

conda config --set changeps1 true

What if a user wants to use the QHub server to compute a new pinned environment, which the user serves via the `qhub_config.yml`?¶

If the user needs to solve a conda env on a QHub server, they need to specify the prefix. For example, conda env create -f env_test.yml --prefix/tmp/test-env where test-env is the env name. It’s not recommended, but there are valid use cases of this operation.

Compute¶

I want to upgrade the instance size the `general` node group, is this possible?¶

The general node group / node pool is the node (usually only one) that hosts most of the pods that QHub relies on for its core services, hub, conda-store, proxy and so on. We have tried to size it so that the initial deployment will work out of the box but also not set it too large that it incurs unnecessary cloud compute costs.

Although each cloud provider has different names and hourly prices for their compute nodes, the default general node group in qhub-config.yaml has 2 vCPU and 8 GB of memory.

Given the possible destructive nature of resizing this node group, we highly recommend backing up your cluster before trying.

Based on some testing, clusters running on Google Kubernetes Engine (GKE), may have some luck performing ths in place upgrade. However, this can’t be said for the other cloud providers and attempting to do so for AWS and Azure will likely result in a catastrophic destruction of your cluster.

Cloud Provider	`general` node upgrade possible?
AWS	No (Danger!)
Azure	No (Danger!)
Digital Ocean	No
GCP	Yes

If modifying the resouce allocation for the general node is ultimately necessary, try increasing the max number of nodes for the general node group. This will mean two nodes - reserved for the general node group - will likely always be running, increasing the operating cost of the cluster.

Alternatively, you can backup your cluster, destroy it and redeploy using the same qhub-config.yaml but with an instance size of your liking.

Experimental features

Troubleshooting guide