在 go 程序中检查 pod 是否在 k8s 集群上运行

Question

I am writing a command line tool in Go which will perform an action based on the existence of a particular pod on a k8s cluster, in a specific namespace.

I could do via command line (shell) invocations within my go program something like

kubectl get pods -n mynapespace l app=myapp

or in case I am not certain about the labels, something even less elegant as:

kubectl get pods -n mynapespace | grep -i somepatternIamcertainabout

However, given that I am using the k8s native language (Go) I was wondering whether there might be a more Go native/specific way of making such an inquiry to the k8s api server, without resorting to shell invocations from within my cli tool.

Answer 1

The kubectl utility is just a convenience wrapper that talks to the Kubernetes API using bog standard HTTP. The Go standard library has a great http package . The perfect fit for what you're trying to accomplish.

In fact, you could just use this official client package from the Kubernetes project itself.

Answer 2

However, given that I am using the k8s native language (Go) I was wondering whether there might be a more Go native/specific way of making such an inquiry to the k8s api server, without resorting to shell invocations from within my cli tool.

If you want to talk with k8s cluster in your programs written in go without resorting to shell invocations, client-go library is the way to go. It contains everything you need to query your k8s api server in your go programs.

What's included

• The kubernetes package contains the clientset to access Kubernetes API.
• The discovery package is used to discover APIs supported by a Kubernetes API server.
• The dynamic package contains a dynamic client that can perform generic operations on arbitrary Kubernetes API objects.
• The plugin/pkg/client/auth packages contain optional authentication plugins for obtaining credentials from external sources.
• The transport package is used to set up auth and start a connection.
• The tools/cache package is useful for writing controllers.