Resource Health

Overview

Argo CD provides built-in health assessment for several standard Kubernetes types, which is then surfaced to the overall Application health status as a whole. The following checks are made for specific types of kubernetes resources:

Deployment, ReplicaSet, StatefulSet DaemonSet

  • Observed generation is equal to desired generation.
  • Number of updated replicas equals the number of desired replicas.

Service

  • If service type is of type LoadBalancer, the status.loadBalancer.ingress list is non-empty, with at least one value for hostname or IP.

Ingress

  • The status.loadBalancer.ingress list is non-empty, with at least one value for hostname or IP.

PersistentVolumeClaim

  • The status.phase is Bound

Argocd App

The health assessement of argoproj.io/Application CRD has been removed in argocd 1.8 (see #3781 for more information). You might need to restore it if you are using app-of-apps pattern and orchestrating syncronization using sync waves. Add the following resource customization in argocd-cm ConfigMap:

  1. ---
  2. apiVersion: v1
  3. kind: ConfigMap
  4. metadata:
  5.   name: argocd-cm
  6.   namespace: argocd
  7.   labels:
  8.     app.kubernetes.io/name: argocd-cm
  9.     app.kubernetes.io/part-of: argocd
  10. data:
  11.   resource.customizations: |
  12.     argoproj.io/Application:
  13.       health.lua: |
  14.         hs = {}
  15.         hs.status = "Progressing"
  16.         hs.message = ""
  17.         if obj.status ~= nil then
  18.           if obj.status.health ~= nil then
  19.             hs.status = obj.status.health.status
  20.             if obj.status.health.message ~= nil then
  21.               hs.message = obj.status.health.message
  22.             end
  23.           end
  24.         end
  25.         return hs

Custom Health Checks

Argo CD supports custom health checks written in Lua. This is useful if you:

  • Are affected by known issues where your Ingress or StatefulSet resources are stuck in Progressing state because of bug in your resource controller.
  • Have a custom resource for which Argo CD does not have a built-in health check.

There are two ways to configure a custom health check. The next two sections describe those ways.

Way 1. Define a Custom Health Check in argocd-cm ConfigMap

Custom health checks can be defined in resource.customizations field of argocd-cm. Following example demonstrates a health check for cert-manager.io/Certificate.

  1. data:
  2.   resource.customizations: |
  3.     cert-manager.io/Certificate:
  4.       health.lua: |
  5.         hs = {}
  6.         if obj.status ~= nil then
  7.           if obj.status.conditions ~= nil then
  8.             for i, condition in ipairs(obj.status.conditions) do
  9.               if condition.type == "Ready" and condition.status == "False" then
  10.                 hs.status = "Degraded"
  11.                 hs.message = condition.message
  12.                 return hs
  13.               end
  14.               if condition.type == "Ready" and condition.status == "True" then
  15.                 hs.status = "Healthy"
  16.                 hs.message = condition.message
  17.                 return hs
  18.               end
  19.             end
  20.           end
  21.         end
  23.         hs.status = "Progressing"
  24.         hs.message = "Waiting for certificate"
  25.         return hs

The obj is a global variable which contains the resource. The script must return an object with status and optional message field.

NOTE: as a security measure you don’t have access to most of the standard Lua libraries.

Way 2. Contribute a Custom Health Check

A health check can be bundled into Argo CD. Custom health check scripts are located in the resource_customizations directory of https://github.com/argoproj/argo-cd. This must have the following directory structure:

  1. argo-cd
  2. |-- resource_customizations
  3. |    |-- your.crd.group.io               # CRD group
  4. |    |    |-- MyKind                     # Resource kind
  5. |    |    |    |-- health.lua            # Health check
  6. |    |    |    |-- health_test.yaml      # Test inputs and expected results
  7. |    |    |    +-- testdata              # Directory with test resource YAML definitions

Each health check must have tests defined in health_test.yaml file. The health_test.yaml is a YAML file with the following structure:

  1. tests:
  2. - healthStatus:
  3.     status: ExpectedStatus
  4.     message: Expected message
  5.   inputPath: testdata/test-resource-definition.yaml

The PR#1139 is an example of Cert Manager CRDs custom health check.