Frequently Asked Questions¶
By now hopefully you have a good understanding of how to get your app running on Spin. Here we answer some common questions and give recipes for common application services.
I noticed strange annotations in my deployment's yaml, for example
nersc.gov/collab_uids. Where do they come from?¶
Spin has some NERSC-specific components to enforce security and make sure users don't accidentally access each others' data. We use Kubernetes mutating webhooks to add annotations to your application's yaml during deployment. At start time, the Open Policy Agent ensures that the annotations are present and that the running app is using shared resources (eg. the Community Filesystem) in accordance with the declared values.
What are the rules that are enforced by these NERSC-added annotations?¶
The rules enforced by OPA contain about 50 checks, ranging from internal consistency (is the annotation present?) to shared resource use (is the application owner allowed to access shared storage at path X?).
I found some code on stackoverflow.com, but it doesn't work in Spin. Why is that?¶
While Spin is running Kubernetes under the hood, it is customized for our NERSC "cloud". Not all features of Kubernetes will work in Spin.
How do I run a Slurm job from Spin?¶
You have several options for running a job on another NERSC compute resource from Spin:
You could host an API service in Spin that is called from the Supercomputer when your job is done
Can I deploy my Spin app using Helm Charts?¶
Yes! Please see our documentation about using Helm.
Why are IP addresses in the 10.42.0.0/16 range showing in my web service access log?¶
Web services in Spin are made accessible externally by an ingress controller, which is a web proxy. Most web services, by default, will therefore log accesses as originating from the IP address of the ingress controller rather than that of the user's workstation.
To change this behavior, configure your web service to obtain the IP address from the
X-Forwarded-For HTTP header, which is a convention for passing this information through web proxies. The ingress controller in Spin is already configured to populate the IP address into the
X-Forwarded-For HTTP header.
Configuration for Apache:
LoadModule remoteip_module modules/mod_remoteip.so
Configuration for nginx:
Help! I was editing my workload and got a big red error¶
If you encounter a big red error starting with:
Forbidden: pod updates may not change fields other than `spec.containers[*].image`, `spec.initContainers[*].image`, `spec.activeDeadlineSeconds` or `spec.tolerations` (only additions to existing tolerations)
when editing your workload, you are probably editing the Pod, not the Deployment. You want to edit the Deployment, not the Pod.