Kubernetes Job Trigger – How to Trigger k8s Job from Different Application

google-cloud-platformgoogle-kubernetes-enginejob-schedulerkubernetes

I will briefly describe my application workflow: I have one application (cronjob), this application read my database and I want to, based on the output from database, run a few jobs in Kubernetes. Sometimes 1 job, sometimes 10 jobs, it depends. Additionally, I would like to pass some env's to this job.

Moreover, I run my Kubernetes Cluster on GCP (Autopilot) so I don't want to have any pod running all the time. So EventListener in Tekton is not a good option since Kubernetes service running the sink logic inside a dedicated Pod.

How Can I do that in the most proper way? Probably I should use K8s API but are there any other options?

Best Answer

The standard way to achieve this would be to provide the rights to create pods, to the service account provided to the cronjob pod.

Then make calls to the Kubernetes API from inside the pod, using kubectl or programatically using a library that can interface with the k8s API.

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I need the container that results from the Job to know when it was scheduled to run. Is this possible?

The short answer is yes.

You can get information about the job and the pod starting/creating timestamp from API-server.

All you need is to call $api-server-ip:port/api/v1/namespace/$namespace-name/pods/$podname

It will receive JSON with details about pod. You can parse this JSON and get the timestamp. The only thing necessary is a pod name (which is usually its hostname). That's all you need to get the timestamp. For parsing JSON you may use any JSON library for any programing language.

Kubernetes – Login to HashiCorp Vault with Kubernetes Auth from Pod Using Vault CLI

While looking through other tutorials I saw, that there is the parameter -field=<FIELD NAME>, that can be used to filter the output of vault write for specific fields.

So the login now looks like this:

export VAULT_TOKEN=$(vault write -field=token auth/kubernetes/login \
    role=vault_backups \
    jwt=$(cat /run/secrets/kubernetes.io/serviceaccount/token))

Thanks anyways.

Best Answer

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Cron – In Kubernetes, how can a container created from a CronJob find out when it was scheduled

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