Patching deployments via kubernetes/client-go

Question

Having trouble figuring out what is wrong. I have a remote kubernetes cluster up and have copied the config locally. I know it is correct because I have gotten other commands to work for me.

The one I can't get to work is a deployment patch. My code:

const namespace = "default"

var clientset *kubernetes.Clientset

func init() {
    kubeconfig := "/Users/$USER/go/k8s-api/config"
    config, err := clientcmd.BuildConfigFromFlags("", kubeconfig)
    if err != nil {
        log.Fatal(err)
    }

    // create the clientset
    clientset, err = kubernetes.NewForConfig(config)
    if err != nil {
        panic(err.Error())
    }
}

func main() {
    deploymentsClient := clientset.ExtensionsV1beta1().Deployments("default")

    patch := []byte(`[{"spec":{"template":{"spec":{"containers":[{"name":"my-deploy-test","image":"$ORG/$REPO:my-deploy0.0.1"}]}}}}]`)
    res, err := deploymentsClient.Patch("my-deploy", types.JSONPatchType, patch)
    if err != nil {
        panic(err)
    }
    fmt.Println(res)

}

All I get back is: panic: the server rejected our request due to an error in our request

Any help appreciated, thanks!

Answer 1

You have mixed up JSONPatchType with MergePatchType ; JSONPatchType wants the input to be RFC 6902 formatted "commands", and in that case can be a JSON array, because there can be multiple commands applied in order to the input document

However, your payload looks much closer to you wanting MergePatchType , in which case the input should not be a JSON array because the source document is not an array of "spec" objects.

Thus, I'd bet just dropping the leading [ and trailing ] , changing the argument to be types.MergePatchType will get you much further along

Answer 2

Actually you should use types.StrategicMergePatchType and remove leading( [ ) and trailing( ] ) parenthesis from patching string.

Merge-patch: With a JSON merge patch, if you want to update a list, you have to specify the entire new list. And the new list completely replaces the existing list.

Strategic-merge-patch: With a strategic merge patch, a list is either replaced or merged depending on its patch strategy. The patch strategy is specified by the value of the patchStrategy key in a field tag in the Kubernetes source code. For example, the Containers field of PodSpec struct has a patchStrategy of merge:

type PodSpec struct {
  ...
  Containers []Container `json:"containers" patchStrategy:"merge" patchMergeKey:"name" ...`

NB: kubectl by-default uses strategic merge patch to patch kubernetes resources.