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client.go
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client.go
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// Copyright 2020-2021 Couchbase, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package client
import (
"sync"
"time"
"github.com/couchbase/service-broker/generated/clientset/servicebroker"
"github.com/golang/glog"
"k8s.io/apimachinery/pkg/api/meta"
"k8s.io/client-go/dynamic"
"k8s.io/client-go/kubernetes"
"k8s.io/client-go/rest"
"k8s.io/client-go/restmapper"
)
// Clients provides an abstraction layer for service broker Kubernetes client interfaces.
type Clients interface {
// Kubernetes returns a typed client for Kubernetes resources.
Kubernetes() kubernetes.Interface
// Broker returns a typed client for service broker resources.
Broker() servicebroker.Interface
// Dynamic returns a dynamic client for Kubernetes resources.
Dynamic() dynamic.Interface
// RESTMapper returns a REST mapps for Kubernetes resources, able to translate
// a resource type into a API endpoint.
RESTMapper() meta.RESTMapper
}
// clientsImpl implements the default Kubernetes client interface using in-cluster configuration.
type clientsImpl struct {
config *rest.Config
kubernetes kubernetes.Interface
broker servicebroker.Interface
dynamic dynamic.Interface
mapper meta.RESTMapper
// lock is used to avoid race warnings.
// A read will still be racy, but not in a bad way.
lock sync.Mutex
}
// New returns a new set of clients for use in-cluster.
// This requires that the container has an API service token mounted.
func New() (Clients, error) {
config, err := rest.InClusterConfig()
if err != nil {
return nil, err
}
kubernetes, err := kubernetes.NewForConfig(config)
if err != nil {
return nil, err
}
broker, err := servicebroker.NewForConfig(config)
if err != nil {
return nil, err
}
dynamic, err := dynamic.NewForConfig(config)
if err != nil {
return nil, err
}
mapper, err := getRESTMapper(kubernetes)
if err != nil {
return nil, err
}
clients := &clientsImpl{
config: config,
kubernetes: kubernetes,
broker: broker,
dynamic: dynamic,
mapper: mapper,
}
go refresh(clients)
return clients, nil
}
// Kubernetes returns a typed client for Kubernetes resources.
func (c *clientsImpl) Kubernetes() kubernetes.Interface {
return c.kubernetes
}
// Broker returns a typed client for service broker resources.
func (c *clientsImpl) Broker() servicebroker.Interface {
return c.broker
}
// Dynamic returns a dynamic client for Kubernetes resources.
func (c *clientsImpl) Dynamic() dynamic.Interface {
return c.dynamic
}
// RESTMapper returns a REST mapps for Kubernetes resources, able to translate
// a resource type into a API endpoint.
func (c *clientsImpl) RESTMapper() meta.RESTMapper {
c.lock.Lock()
defer c.lock.Unlock()
return c.mapper
}
// getRESTMapper is a shared function to poll the discovery API. This is a
// very expensive call so should be used with caution.
func getRESTMapper(client kubernetes.Interface) (meta.RESTMapper, error) {
groupresources, err := restmapper.GetAPIGroupResources(client.Discovery())
if err != nil {
return nil, err
}
return restmapper.NewDiscoveryRESTMapper(groupresources), nil
}
// refresh is used to refresh the REST mapper periodically. This allows the
// service broker to pick up, and forget about, CRDs as they are added and
// removed from the platform. While we could just use a watch, CRDs being
// cluster scoped resources will introduce an unnecessary privilege escallation.
// The broker should be able to run as a "userspace" application.
func refresh(c *clientsImpl) {
for {
// Poll once a minute. We should make this configurable.
<-time.After(time.Minute)
mapper, err := getRESTMapper(c.kubernetes)
if err != nil {
glog.Warningf("failed to refersh REST mapper: %v", err)
continue
}
glog.Info("refreshed REST mapper")
c.lock.Lock()
c.mapper = mapper
c.lock.Unlock()
}
}