How to query a openshift resource in Go

A common chore in automation is to take a command line, like this:

oc get nmstateconfig/cnfde17.redhat.com -n cnfde17 -o yaml

And translate it to Go.

First run the command above and search for the first response lines:

apiVersion: agent-install.openshift.io/v1beta1
kind: NMStateConfig
metadata:
  annotations:

In this case you need to start your go code with this import:

import assistedv1beta1 "github.com/openshift/assisted-service/api/v1beta1"

And not with the NMstate import, despite the kind.

For the query you need an object type. In the command line above you queried a spesific namespace: cnfde17, so do this: Now you need to create a typed namespace:

import types "k8s.io/apimachinery/pkg/types"
...
typedNamespace := types.NamespacedName{}
typedNamespace.Name = clusterName
typedNamespace.Namespace = namespace

The query works by supplying an object of the kind of resource you want to query in the namespace. In this case the kind will translate to:

nmStateConfig := assistedv1beta1.NMStateConfig{}

And the query is therefor:

err := Client.Get(context.Background(), typedNamespace, &nmStateConfig)

Here is a nice function with all the above:

// GetNMStateConfig is used to get the NMStateConfig for a specified cluster and namespace.
func GetNMStateConfig(clusterName string, namespace string) (assistedv1beta1.NMStateConfig, error) {
	// Create a typed namespace object
	typedNamespace := types.NamespacedName{}
	typedNamespace.Name = clusterName
	typedNamespace.Namespace = namespace

	// Create a NMStateConfig object
	nmStateConfig := assistedv1beta1.NMStateConfig{}

	// Get the NMStateConfig from the hub
	err := Client.Get(GetZtpContext(), typedNamespace, &nmStateConfig)

	// need to match meta.NoKindMatchError with err.
	if err != nil {
		return assistedv1beta1.NMStateConfig{}, err
	}

	return nmStateConfig, nil
}