The AppDynamics Cluster Agent is a lightweight Agent written in Golang for monitoring Kubernetes and OpenShift clusters. The Cluster Agent helps you monitor and understand how Kubernetes infrastructure affects your applications and business performance. With the Cluster Agent, you can collect metadata, metrics, and events for a Kubernetes cluster. The Cluster Agent works on Red Hat OpenShift and cloud-based Kubernetes platforms, such as: Amazon EKS, Azure AKS, and Pivotal PKS.

Cluster Monitoring in the Controller

The Cluster Agent monitors events and metrics of Kubernetes or OpenShift clusters. It also tracks the state of most Kubernetes resources: pods, replica sets, deployments, services, persistent volumes, nodes, and so on. The data is received through the Kubernetes API at a configurable interval, and is sent to the AppDynamics Controller. See Cluster Metrics.

Cluster Agent and Server Visibility with Docker Monitoring

AppDynamics Server Visibility monitors the worker nodes at a more detailed level. Server Visibility includes the ability to monitor running containers through Docker Monitoring, however, the Cluster Agent also monitors the same containers through the Kubernetes API. You cannot run Server Visibility with Docker Monitoring enabled and the Cluster Agent concurrently. Doing so may result in your data being overwritten, and may lead to unpredictable behaviors.

When you deploy both Agents to the cluster, ensure that the Machine Agent is deployed with Docker Visibility disabled. See Controller Settings for Docker Visibility.

Cluster Dashboard Metrics

The Cluster Dashboard provides an overview of potential issues with cluster health, grouped by category and severity. It shows error events, evictions, node resource starvation, distribution of pod phases, and issues associated with:

  • Applications
  • Cluster configuration
  • Image or storage access
  • Security access errors
  • Quota violations

The dashboard contains cluster resource capacity stats and resource usage data relative to the deployment requests and limits for CPU, Memory, and Storage. The dashboard also provides real-time stats on the state of monitored objects on the cluster, best-practice violations, and missing dependencies. See Monitor Cluster Health

Cluster Agent Health Rules 

You can create Cluster Agent Health Rules based on cluster metrics. Because Health Rules for Clusters are created using server health rules, the health rule violations for Clusters show as a server health rule violation. When creating the Health Rule, in the Affected Entities section, select Custom and then select your Cluster Agent from the list of machines. When setting the Critical/Warning conditions, the entire metric tree displays. Select the Cluster Agent metrics for which to create the Health Rule. To create Health Rules for Cluster Agent metrics, follow the Create a Health Rule procedures.

You can create Health Rules for these metrics examples: 

  • Number of error events
  • Number of evictions
  • Number of threats
  • Nodes with disk pressure
  • Nodes with memory pressure
  • CPU/Memory utilization versus to quotas

Cluster Agent Logs

The AppDynamics Cluster Agent writes log files to the <cluster-agent>/logs/cluster-agent-log file. Use stdout to configure to write logs. See View Cluster Agent Logs.