Example Deployment Health Notification

The below HealthCheck YAML definition considers all the cluster Deployments. It matches any Deployment in the metrics namespace:

1. Healthy: All requested replicas are available and ready, and there are no unavailable replicas reported.
2. Degraded: Marked if there are unavailable replicas, or if the available/ready counts are less than the desired spec.

---
apiVersion: lib.projectsveltos.io/v1beta1
kind: HealthCheck
metadata:
  name: metrics-deployment-replicas
spec:
  resourceSelectors:
  - group: "apps"
    version: v1
    kind: Deployment
    namespace: metrics
  evaluateHealth: |
    function evaluate()
      local hs = {}
      hs.status = "Healthy"
      hs.message = ""
      local unhealthy = {}

      for _, resource in ipairs(resources) do
        local status = resource.status or {}
        local spec = resource.spec or {}
        local metadata = resource.metadata or {}

        local desired = spec.replicas or 0
        local available = status.availableReplicas or 0
        local ready = status.readyReplicas or 0
        local unavailable = status.unavailableReplicas or 0

        local issue = nil

        -- 1. Check for explicit unavailable replicas
        if unavailable > 0 then
          issue = string.format("Deployment %s/%s has %d unavailable replicas",
                  metadata.namespace, metadata.name, unavailable)

        -- 2. Check if available matches desired
        elseif available < desired then
          issue = string.format("Deployment %s/%s has %d available replicas (Expected %d)",
                  metadata.namespace, metadata.name, available, desired)

        -- 3. Check if ready matches desired
        elseif ready < desired then
          issue = string.format("Deployment %s/%s has %d ready replicas (Expected %d)",
                  metadata.namespace, metadata.name, ready, desired)
        end

        if issue then
          table.insert(unhealthy, {resource = resource, message = issue, status = "Degraded"})
        end
      end

      -- Update final health status if any issues were found
      if #unhealthy > 0 then
        hs.resources = unhealthy
      end

      return hs
    end