kube-ns-suspender

README

kube-ns-suspender

Kubernetes controller managing namespaces life cycle.

• kube-ns-suspender
  • Goal
  • Usage
    • Internals
      • The watcher
      • The suspender
    • Flags
    • Resources
    • States
    • Annotations
      • On namespaces
      • On resources
        • Deployments and Stateful Sets
        • Cronjobs
  • Development flow
  • Testing
  • Contributing
  • License

Goal

This controller watches the cluster's namespaces and "suspends" them by scaling to 0 some of the resources within those namespaces at a given time. However, once a namespace is in a "suspended" state, it will not be restarted automatically the following day (or whatever). This allows to "reactivate" namespaces only when required, and reduce costs.

Usage

Internals

This controller can be splitted into 2 parts:

• The watcher
• The suspender

The watcher

The watcher function is charged to check every X seconds (X being set by the flag -watcher-idle or by the KUBE_NS_SUSPENDER_WATCHER_IDLE environement variable) all the namespaces. When it found namespace that have the kube-ns-suspender/desiredState annotation, it sends it to the suspender. It also manages all the metrics that are exposed about the watched namespaces states.

The suspender

The suspender function does all the work of reading namespaces/resources annotations, and (un)suspending them when required.

Flags

/* explain the different flags, the associated env vars... */

Resources

Currently supported resources are:

• deployments
• stateful sets
• cronjobs

States

Namespaces watched by kube-ns-suspender can be in 3 differents states:

• Running: the namespace is "up", and all the resources have the desired number of replicas.
• Suspended: the namespace is "paused", and all the supported resources are scaled down to 0 or suspended.

Annotations

Annotations are employed to save the original state of a resource.

On namespaces

In order for a namespace to be watched by the controller, it needs to have the kube-ns-suspender/desiredState annotation set to any of the supported values, which are:

• Running
• Suspended

To be suspended at a given time, a namespace must have the annotation kube-ns-suspender/suspendAt set to a valid value. Valid values are any values that match the time.Kitchen time format, for example: 8:15PM, 12:45AM...

On resources

Deployments and Stateful Sets

As those resources have a spec.replicas value, they must have a kube-ns-suspender/originalReplicas annotation that must be the same as the spec.replicas value. This annotation will be used when a resource will be "unsuspended" to set the original number of replicas.

Cronjobs

Cronjobs have a spec.suspend value that indicates if they must be runned or not. As this value is a boolean, no other annotations are required.

Development flow

To test the modifications in real-time, this project uses devspace. It is configured to use the manifests in manifests/dev/.

First, set the namespace to use:

devspace use namespace kube-ns-suspender-testing

Deploy the testing namespace with mock resources:

kubectl apply -f manifests/testing-namespace

Then deploy your dev version of kube-ns-suspender:

devspace dev

⚠

devspace and kubectl will deploy the manifests in the cluster set by the current context. be sure to not deploy in the wrong cluster.

Once the dev deployment is over, you'll have access to a shell in the container. You can start developing!

When you are done, you can stop everything by closing your shell in the container and running:

devspace purge

and:

kubectl delete -f manifests/testing-namespace/

Testing

The controller at each PR and push using bats-detik.

Contributing

/* add CONTRIBUTING file at root */

License

MIT