Out-of-tree SWAP with WASP

WASP can be used in order to grant SWAP to certain containers using an out-of-(kubernetes)-tree mechanism based on an OCI hook.

The design can be found in openshift/enhancements#1630

Scope

• Node
  • Enable swap on the node
  • Disable swap in the system.slice
  • Set io latency for system.slice
  • Install an OCI hook to enable swap
  • Set memory.high for kubepods.slice
  • Configure soft eviction
• Workloads
  • Enable swap=max for every burstable pod using an OCI hook
  • Set limited swap for workloads (TODO)

Build

$ bash to.sh build
$ bash to.sh push  # only to my account right now

Deploy

# Deploy to OCP 4.15 or higher
$ oc login --token= …
$ bash to.sh deploy

Demo

$ oc apply -f manifests/static.yaml
$ oc apply -f manifests/stress.yaml
# Now increase the stress deployment replicacount in order to push out
# memory of static pods

Destroy

$ bash to.sh destroy