Set priorityClass on prometheus pods and change memory/retention period

What does this MR do and why?

Based on issue #3068 (closed), during rolling update process, prometheus pods reports OOM-killed while replaying WAL. In order to overcome this situation we should adapt the configuration, the aim of this MR is to decrease the retention period to 5d ( it will be the default value but it's up to end users to change it, if they want that) and set priorityClass with low priority on prometheus pod (see discussion: !5945 (comment 2853871467))

Setting a priorityClass on a pod without limits can be a benefit but also could affect the node:

• Without limits prometheus pod is able to use as much memory as possible on the node to replay its WAL
• In case of memory pressure reported by kubelet having a priorityClass with a negative value means that prometheus pod should be evicted first and rescheduled on another node with enough resources

cc: @feleouet @cristian.manda @stoub @alinhg

Related reference(s)

Test coverage

CI configuration

Below you can choose test deployment variants to run in this MR's CI.

Click to open to CI configuration

Legend:

Icon	Meaning	Available values
☁️	Infra Provider	capd, capo, capm3
🚀	Bootstrap Provider	kubeadm (alias kadm), rke2, okd, ck8s
🐧	Node OS	ubuntu, suse, na, leapmicro
🛠️	Deployment Options	light-deploy, dev-sources, ha, misc, maxsurge-0, logging, no-logging, cilium
🎬	Pipeline Scenarios	Available scenario list and description
🟢	Enabled units	Any available units name, by default apply to management and workload cluster. Can be prefixed by mgmt: or wkld: to be applied only to a specific cluster type

• 🎬 preview ☁️ capd 🚀 kadm 🐧 ubuntu

• 🎬 preview ☁️ capo 🚀 rke2 🐧 suse

• 🎬 preview ☁️ capm3 🚀 rke2 🐧 ubuntu

• ☁️ capd 🚀 kadm 🛠️ light-deploy 🐧 ubuntu

• ☁️ capd 🚀 rke2 🛠️ light-deploy 🐧 suse

• ☁️ capo 🚀 rke2 🐧 suse

• ☁️ capo 🚀 rke2 🐧 leapmicro

• ☁️ capo 🚀 kadm 🐧 ubuntu

• ☁️ capo 🚀 kadm 🐧 ubuntu 🟢 neuvector,mgmt:harbor

• ☁️ capo 🚀 rke2 🎬 rolling-update 🛠️ ha 🐧 ubuntu

• ☁️ capo 🚀 kadm 🎬 wkld-k8s-upgrade 🐧 ubuntu

• ☁️ capo 🚀 rke2 🎬 rolling-update-no-wkld 🛠️ ha 🐧 suse

• ☁️ capo 🚀 rke2 🎬 sylva-upgrade-from-1.5.x 🛠️ ha 🐧 ubuntu

• ☁️ capo 🚀 rke2 🎬 sylva-upgrade-from-1.5.x 🛠️ ha,misc 🐧 ubuntu

• ☁️ capo 🚀 rke2 🛠️ ha,misc 🐧 ubuntu

• ☁️ capo 🚀 rke2 🛠️ ha,misc🐧 suse

• ☁️ capm3 🚀 rke2 🐧 suse

• ☁️ capm3 🚀 kadm 🐧 ubuntu

• ☁️ capm3 🚀 ck8s 🐧 ubuntu

• ☁️ capm3 🚀 kadm 🎬 rolling-update-no-wkld 🛠️ ha,misc 🐧 ubuntu

• ☁️ capm3 🚀 rke2 🎬 wkld-k8s-upgrade 🛠️ ha 🐧 suse

• ☁️ capm3 🚀 kadm 🎬 rolling-update 🛠️ ha 🐧 ubuntu

• ☁️ capm3 🚀 rke2 🎬 sylva-upgrade-from-1.5.x 🛠️ ha 🐧 suse

• ☁️ capm3 🚀 rke2 🛠️ misc,ha 🐧 suse

• ☁️ capm3 🚀 rke2 🎬 sylva-upgrade-from-1.5.x 🛠️ ha,misc 🐧 suse

• ☁️ capm3 🚀 kadm 🎬 rolling-update 🛠️ ha 🐧 suse

• ☁️ capm3 🚀 ck8s 🎬 rolling-update 🛠️ ha 🐧 ubuntu

• ☁️ capm3 🚀 rke2|okd 🎬 no-update 🐧 ubuntu|na

Global config for deployment pipelines

• autorun pipelines
• allow failure on pipelines
• record sylvactl events

Notes:

• Enabling autorun will make deployment pipelines to be run automatically without human interaction
• Disabling allow failure will make deployment pipelines mandatory for pipeline success.
• if both autorun and allow failure are disabled, deployment pipelines will need manual triggering but will be blocking the pipeline

Be aware: after configuration change, pipeline is not triggered automatically. Please run it manually (by clicking the run pipeline button in Pipelines tab) or push new code.