Monitor an MKE cluster

You can monitor the status of MKE using the web UI or the CLI. You can also use the _ping endpoint to build monitoring automation.

The first place to check the status of MKE is the MKE web UI, since it shows warnings for situations that require your immediate attention. Administrators might see more warnings than regular users.

You can also navigate to the Nodes page, to see if all the nodes managed by MKE are healthy or not.

Each node has a status message explaining any problems with the node. In this example, a Windows worker node is down. Click the node to get more info on its status. In the details pane, click Actions and select Agent logs to see the log entries from the node.

Use the CLI to monitor the status of a cluster

You can also monitor the status of a MKE cluster using the Docker CLI client. Download a MKE client certificate bundle and then run:

docker node ls

As a rule of thumb, if the status message starts with [Pending], then the current state is transient and the node is expected to correct itself back into a healthy state.

Monitoring automation

You can use the https://<mke-manager-url>/_ping endpoint to check the health of a single MKE manager node. When you access this endpoint, the MKE manager validates that all its internal components are working, and returns one of the following HTTP error codes:

  • 200, if all components are healthy

  • 500, if one or more components are not healthy

If an administrator client certificate is used as a TLS client certificate for the _ping endpoint, a detailed error message is returned if any component is unhealthy.

If you’re accessing the _ping endpoint through a load balancer, you’ll have no way of knowing which MKE manager node is not healthy, since any manager node might be serving your request. Make sure you’re connecting directly to the URL of a manager node, and not a load balancer. In addition, please be aware that pinging the endpoint with HEAD will result in a 404 error code. It is better to use GET instead.

Monitoring vulnerability counts

For those implementations with a subscription, MKE displays image vulnerability count data from the MSR image scanning feature. MKE displays vulnerability counts for containers, Swarm services, pods, and images.

To enable this feature, MSR 2.6 is required and single sign-on with MKE must be enabled.

Monitoring disk usage

Web UI disk usage metrics, including free space, only reflect the Docker managed portion of the filesystem: /var/lib/docker. To monitor the total space available on each filesystem of a MKE worker or manager, you must deploy a third-party monitoring solution to monitor the operating system.