110 lines
3.1 KiB
Go
110 lines
3.1 KiB
Go
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/*
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Copyright 2016 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package dnsprovider
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import (
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"fmt"
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"io"
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"os"
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"sync"
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"github.com/golang/glog"
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)
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// Factory is a function that returns a dnsprovider.Interface.
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// The config parameter provides an io.Reader handler to the factory in
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// order to load specific configurations. If no configuration is provided
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// the parameter is nil.
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type Factory func(config io.Reader) (Interface, error)
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// All registered dns providers.
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var providersMutex sync.Mutex
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var providers = make(map[string]Factory)
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// RegisterDnsProvider registers a dnsprovider.Factory by name. This
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// is expected to happen during startup.
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func RegisterDnsProvider(name string, cloud Factory) {
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providersMutex.Lock()
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defer providersMutex.Unlock()
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if _, found := providers[name]; found {
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glog.Fatalf("DNS provider %q was registered twice", name)
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}
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glog.V(1).Infof("Registered DNS provider %q", name)
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providers[name] = cloud
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}
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// GetDnsProvider creates an instance of the named DNS provider, or nil if
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// the name is not known. The error return is only used if the named provider
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// was known but failed to initialize. The config parameter specifies the
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// io.Reader handler of the configuration file for the DNS provider, or nil
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// for no configuration.
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func GetDnsProvider(name string, config io.Reader) (Interface, error) {
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providersMutex.Lock()
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defer providersMutex.Unlock()
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f, found := providers[name]
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if !found {
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return nil, nil
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}
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return f(config)
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}
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// Returns a list of registered dns providers.
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func RegisteredDnsProviders() []string {
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registeredProviders := make([]string, len(providers))
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i := 0
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for provider := range providers {
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registeredProviders[i] = provider
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i = i + 1
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}
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return registeredProviders
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}
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// InitDnsProvider creates an instance of the named DNS provider.
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func InitDnsProvider(name string, configFilePath string) (Interface, error) {
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var dns Interface
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var err error
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if name == "" {
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glog.Info("No DNS provider specified.")
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return nil, nil
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}
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if configFilePath != "" {
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var config *os.File
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config, err = os.Open(configFilePath)
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if err != nil {
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return nil, fmt.Errorf("Couldn't open DNS provider configuration %s: %#v", configFilePath, err)
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}
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defer config.Close()
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dns, err = GetDnsProvider(name, config)
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} else {
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// Pass explicit nil so plugins can actually check for nil. See
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// "Why is my nil error value not equal to nil?" in golang.org/doc/faq.
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dns, err = GetDnsProvider(name, nil)
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}
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if err != nil {
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return nil, fmt.Errorf("could not init DNS provider %q: %v", name, err)
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}
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if dns == nil {
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return nil, fmt.Errorf("unknown DNS provider %q", name)
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}
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return dns, nil
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}
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