I'm setting up a kubernet cluster to roll out our container applications. The applications actually need all labels, but the labels are longer than 63 characters and I get an error. This makes me dependent on annotations.
An annotation for a service looks like this: com.example.development.london/component.proxy-config.secure-routes.backend.proxy-path. The / only serves to bypass an RFC domain error.
In a Golang application all services of a namespace are requested. Actually based on the labels. For this I have used the following code so far.
func (kc *KubernetesCollector) generateRoutes(errorChannel chan<- error) {
log.Println("INFO: Try to generate routes")
services, err := kc.iface.Services(kc.namespace).List(metav1.ListOptions{
LabelSelector: fmt.Sprintf("%s==true", ConvertLabelToKubernetesAnnotation(ProxyConfDiscoverableLabel)),
})
...
func ConvertLabelToKubernetesAnnotation(label string) string {
return strings.Replace(label, "com.example.development.london.", "com.example.development.london/", -1)
}
But there is no possibility to return the services using annotations. Does anyone know another way how I can get all services that apply to an annotation with Go?
There is no FieldSelector for annotations. What you can do is get all services into your list and then filter them based on annotations found in each.
As specified in the Kubernetes documentation, annotations are meant for non-identifying information, so naturally you shouldn't use them for finding objects.
If that's an option, you can attach a prefix (max length of 253 characters) to your label in this manner: <label prefix>/<label name>. Additional information can be found from the link provided above.