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

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.

data:
  resource.customizations: |
    cert-manager.io/Certificate:
      health.lua: |
        hs = {}
        if obj.status ~= nil then
          if obj.status.conditions ~= nil then
            for i, condition in ipairs(obj.status.conditions) do
              if condition.type == "Ready" and condition.status == "False" then
                hs.status = "Degraded"
                hs.message = condition.message
                return hs
              end
              if condition.type == "Ready" and condition.status == "True" then
                hs.status = "Healthy"
                hs.message = condition.message
                return hs
              end
            end
          end
        end

        hs.status = "Progressing"
        hs.message = "Waiting for certificate"
        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:

argo-cd
|-- resource_customizations
|    |-- your.crd.group.io               # CRD group
|    |    |-- MyKind                     # Resource kind
|    |    |    |-- health.lua            # Health check
|    |    |    |-- health_test.yaml      # Test inputs and expected results
|    |    |    +-- 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:

tests:
- healthStatus:
    status: ExpectedStatus
    message: Expected message
  inputPath: testdata/test-resource-definition.yaml

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