[addon-operator] added new metrics

[diyliv]

Description

Changes in addon-operator:

1. New metric deckhouse_tasks_queue_head_info with labels queue, module, task_type, hook — shows what task is at the head of each non-empty queue.
2. New label critical on deckhouse_mm_module_info — value from BasicModule.GetCritical().

Why do we need it, and what problem does it solve?

deckhouse_tasks_queue_length exposes only queue — no visibility into which task/module/hook is at the head of a hung queue. Severity is always "7" regardless of module criticality. deckhouse_mm_module_info lacks a critical label.

This change enables severity-tiered alerting based on module criticality: critical module queues (e.g., cni-cilium) get severity 4, non-critical (e.g., console) get severity 6, and global/parallel task hangs get severity 4. Operators get immediate signal about what is stuck and how important it is.

Example

critical label on deckhouse_mm_module_info

deckhouse_mm_module_info{critical="true",enabled="true",module="cni-cilium"} 1
deckhouse_mm_module_info{critical="true",enabled="true",module="control-plane-manager"} 1
deckhouse_mm_module_info{critical="true",enabled="true",module="deckhouse"} 1
deckhouse_mm_module_info{critical="true",enabled="true",module="node-manager"} 1
deckhouse_mm_module_info{critical="true",enabled="false",module="cloud-provider-aws"} 1
deckhouse_mm_module_info{critical="true",enabled="false",module="cloud-provider-vsphere"} 1
deckhouse_mm_module_info{critical="false",enabled="true",module="cert-manager"} 1
deckhouse_mm_module_info{critical="false",enabled="true",module="console"} 1
deckhouse_mm_module_info{critical="false",enabled="true",module="ingress-nginx"} 1

26 modules with critical="true", 41 with critical="false". Verified on dev cluster.

deckhouse_tasks_queue_head_info with non-empty queues

Captured during startup (tasks queued across main, parallel, and module-specific queues):

deckhouse_tasks_queue_head_info{hook="",module="node-manager",queue="main",task_type="ModuleRun"} 1
deckhouse_tasks_queue_head_info{hook="",module="ingress-nginx",queue="parallel_queue_12",task_type="ModuleRun"} 1
deckhouse_tasks_queue_head_info{hook="",module="upmeter",queue="parallel_queue_18",task_type="ModuleRun"} 1
deckhouse_tasks_queue_head_info{hook="300-prometheus/hooks/disk_metrics.go",module="prometheus",queue="/modules/prometheus/disk_metrics",task_type="ModuleHookRun"} 1
deckhouse_tasks_queue_head_info{hook="402-ingress-nginx/hooks/safe_daemonset_update.go",module="ingress-nginx",queue="/modules/ingress-nginx/safe_daemonset_update",task_type="ModuleHookRun"} 1

When all queues are empty (steady state), deckhouse_tasks_queue_head_info correctly produces no series. Verified on dev cluster.

Checklist

• Unit tests pass (11 tests in pkg/metrics + full pkg/... suite).
• Alert rules in deckhouse (separate PR).
• Documentation updated.
• Deployed to dev cluster, critical label and tasks_queue_head_info verified.

Changelog entries

section: deckhouse
type: feature
summary: Rework D8DeckhouseQueueIsHung alert with queue head info and severity based on module criticality.