Instantly share code, notes, and snippets.

Embed
What would you like to do?
Example showing how to patch an Istio VirtualService CRDs Golang
// Example showing how to patch Kubernetes resources.
package main
import (
"encoding/json"
"fmt"
"k8s.io/apimachinery/pkg/runtime/schema"
types "k8s.io/apimachinery/pkg/types"
"k8s.io/client-go/dynamic"
_ "k8s.io/client-go/plugin/pkg/client/auth"
"k8s.io/client-go/tools/clientcmd"
)
var (
// Leave blank for the default context in your kube config.
context = ""
// Name of the VirtualService to weight, and the two weight values.
virtualServiceName = "service2"
weight1 = uint32(50)
weight2 = uint32(50)
)
// patchStringValue specifies a patch operation for a string.
type patchStringValue struct {
Op string `json:"op"`
Path string `json:"path"`
Value string `json:"value"`
}
// patchStringValue specifies a patch operation for a uint32.
type patchUInt32Value struct {
Op string `json:"op"`
Path string `json:"path"`
Value uint32 `json:"value"`
}
func setVirtualServiceWeights(client dynamic.Interface, virtualServiceName string, weight1 uint32, weight2 uint32) error {
// Create a GVR which represents an Istio Virtual Service.
virtualServiceGVR := schema.GroupVersionResource{
Group: "networking.istio.io",
Version: "v1alpha3",
Resource: "virtualservices",
}
// Weight the two routes - 50/50.
patchPayload := make([]patchUInt32Value, 2)
patchPayload[0].Op = "replace"
patchPayload[0].Path = "/spec/http/0/route/0/weight"
patchPayload[0].Value = 50
patchPayload[1].Op = "replace"
patchPayload[1].Path = "/spec/http/0/route/1/weight"
patchPayload[1].Value = 50
patchBytes, _ := json.Marshal(patchPayload)
// Apply the patch to the 'service2' service.
_, err := client.Resource(virtualServiceGVR).Namespace("default").Patch(virtualServiceName, types.JSONPatchType, patchBytes)
return err
}
func main() {
// Get the local kube config.
fmt.Printf("Connecting to Kubernetes Context %v\n", context)
config, err := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(
clientcmd.NewDefaultClientConfigLoadingRules(),
&clientcmd.ConfigOverrides{CurrentContext: context}).ClientConfig()
if err != nil {
panic(err.Error())
}
// Creates the dynamic interface.
dynamicClient, err := dynamic.NewForConfig(config)
if err != nil {
panic(err.Error())
}
// Re-balance the weights of the hosts in the virtual service.
setVirtualServiceWeights(dynamicClient, "service2", 50, 50)
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment