k8s-slurm-injector

A Kubernetes admission webhook that injects a slurm job when a Pod is created.

This is implemented based on slok/k8s-webhook-example.

Deployment

Prepare ssh-key

You need to generate a new ssh-key as k8s-slurm-injector pod must be able to login to a node running slurmd via ssh.

$ ssh-keygen
(follow the wizard and `id_rsa` and `id_rsa.pub` will be generated)

Then, copy the content of id_rsa.pub into ${HOME}/.ssh/authorized_keys on a node where slurmd is running.

After that, create a secret containing id_rsa as follows:

$ kubectl create ns k8s-slurm-injector
$ kubectl -n k8s-slurm-injector create secret generic k8s-slurm-injector-ssh-id-rsa --from-file=./

Make sure that k8s-slurm-injector-ssh-id-rsa exists in namespace k8s-slurm-injector.

$ kubectl -n k8s-slurm-injector get secrets
...
k8s-slurm-injector-ssh-id-rsa   Opaque                                2      1m
...

Deploy

Clone this repository and generate certificates for deployment.

$ git clone https://github.com/d-hayashi/k8s-slurm-injector.git
$ cd k8s-slurm-injector
$ make gen-deploy-certs

Then, replace the following parts in deploy/app.yaml

• <SSH Destination>: Username and IP-address of the node running slurm with format username@ip-address
• <SSH Port>: Port number of the SSH-server

After that, deploy app-certs and app and make sure deployment k8s-slurm-injector becomes ready.

$ cd deploy
$ kubectl apply -f app-certs.yaml
$ kubectl apply -f app.yaml
$ kubectl -n k8s-slurm-injector get deployment --watch
NAME                 READY   UP-TO-DATE   AVAILABLE   AGE
k8s-slurm-injector   0/1     1            0           1s
k8s-slurm-injector   1/1     1            1           10s

When it is confirmed, deploy webhooks.

$ kubectl apply -f webhooks.yaml

If deployment k8s-slurm-injector does not become ready, you should check logs.

$ kubectl -n k8s-slurm-injector logs deployment/k8s-slurm-injector

Test

To check the behavior of k8s-slurm-injector, you can deploy sample-pod.

$ kubectl apply -f sample-pod.yaml

Note that pod is labeled with k8s-slurm-injector/injection: enabled.
Slurm jobs are injected only if resources have this label.

Webhooks

inject-slurm-job.d-hayashi.dev

• Webhook type: Mutating.
• Resources affected: cronjobs, jobs, pods

This webhook injects a slurm-job at the time containers start in the pod.