How to Obtain Detailed Pod Status Information using Client-Go?

Customizing Pod Status Output Using Kubernetes Client-Go

When using the k8s.io/client-go/kubernetes client-go, it is possible to retrieve the pod.Status which includes the pod.Status.Phase. However, this information is limited to five values: Pending, Running, Succeeded, Failed, and Unknown.

If you want to get more detailed status information, such as "Init:0/1" or "PodInitializing," which are displayed in the Status column of kubectl get pods, there are a few options available.

Server-Side Calculation

Typically, you don't need to calculate the status on the client side because it's done at the server level. These statuses are calculated using the ServerPrint function, which defaults to the Kubernetes TablePrinter. The TablePrinter handles the conversion of server-returned data into a human-readable format.

The logic for calculating the Status column is handled in the codebase at:

• https://github.com/kubernetes/kubernetes/tree/4477bf02f211093b32cf58f64aa42aff77daea61/pkg/printers/internalversion

Client-Side Calculation

If you still prefer to calculate the status on the client side, you can use the kubeconfig library to access the Kubernetes API server. However, this requires a deep understanding of the Kubernetes API and can be quite complex.

Using Printers

Another option is to use custom printers. The client-go library provides a number of functions for printing objects, including:

• https://github.com/kubernetes/kubernetes/tree/master/staging/src/k8s.io/cli-runtime/pkg/printers

You can use these functions to create a custom printer that matches the format of kubectl get pods.

Conclusion

Retrieving the same Pod status information as kubectl get pods is possible using the client-go library. However, it's worth noting that this information is usually calculated on the server side, and you may be able to avoid the need for client-side calculation. If you do need to customize the status output, using printers is a good approach.

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