ca6bdba014
This is step one for cross-region ECR support and has no visible effects yet. I'm not crazy about the name LazyProvide. Perhaps the interface method could remain like that and the package method of the same name could become LateBind(). I still don't understand why the credential provider has a DockerConfigEntry that has the same fields but is distinct from docker.AuthConfiguration. I had to write a converter now that we do that in more than one place. In step two, I'll add another intermediate, lazy provider for each AWS region, whose empty LazyAuthConfiguration will have a refresh time of months or years. Behind the scenes, it'll use an actual ecrProvider with the usual ~12 hour credentials, that will get created (and later refreshed) only when kubelet is attempting to pull an image. If we simply turned ecrProvider directly into a lazy provider, we would bypass all the caching and get new credentials for each image pulled.
120 lines
3.4 KiB
Go
120 lines
3.4 KiB
Go
/*
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Copyright 2014 The Kubernetes Authors All rights reserved.
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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 credentialprovider
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import (
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"os"
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"reflect"
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"sync"
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"time"
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docker "github.com/fsouza/go-dockerclient"
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"github.com/golang/glog"
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)
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// DockerConfigProvider is the interface that registered extensions implement
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// to materialize 'dockercfg' credentials.
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type DockerConfigProvider interface {
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Enabled() bool
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Provide() DockerConfig
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// LazyProvide() gets called after URL matches have been performed, so the
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// location used as the key in DockerConfig would be redundant.
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LazyProvide() *DockerConfigEntry
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}
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func LazyProvide(creds LazyAuthConfiguration) docker.AuthConfiguration {
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if creds.Provider != nil {
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entry := *creds.Provider.LazyProvide()
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return DockerConfigEntryToLazyAuthConfiguration(entry).AuthConfiguration
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} else {
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return creds.AuthConfiguration
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}
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}
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// A DockerConfigProvider that simply reads the .dockercfg file
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type defaultDockerConfigProvider struct{}
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// init registers our default provider, which simply reads the .dockercfg file.
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func init() {
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RegisterCredentialProvider(".dockercfg",
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&CachingDockerConfigProvider{
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Provider: &defaultDockerConfigProvider{},
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Lifetime: 5 * time.Minute,
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})
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}
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// CachingDockerConfigProvider implements DockerConfigProvider by composing
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// with another DockerConfigProvider and caching the DockerConfig it provides
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// for a pre-specified lifetime.
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type CachingDockerConfigProvider struct {
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Provider DockerConfigProvider
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Lifetime time.Duration
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// cache fields
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cacheDockerConfig DockerConfig
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expiration time.Time
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mu sync.Mutex
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}
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// Enabled implements dockerConfigProvider
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func (d *defaultDockerConfigProvider) Enabled() bool {
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return true
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}
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// Provide implements dockerConfigProvider
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func (d *defaultDockerConfigProvider) Provide() DockerConfig {
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// Read the standard Docker credentials from .dockercfg
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if cfg, err := ReadDockerConfigFile(); err == nil {
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return cfg
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} else if !os.IsNotExist(err) {
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glog.V(4).Infof("Unable to parse Docker config file: %v", err)
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}
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return DockerConfig{}
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}
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// LazyProvide implements dockerConfigProvider. Should never be called.
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func (d *defaultDockerConfigProvider) LazyProvide() *DockerConfigEntry {
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return nil
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}
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// Enabled implements dockerConfigProvider
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func (d *CachingDockerConfigProvider) Enabled() bool {
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return d.Provider.Enabled()
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}
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// LazyProvide implements dockerConfigProvider. Should never be called.
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func (d *CachingDockerConfigProvider) LazyProvide() *DockerConfigEntry {
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return nil
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}
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// Provide implements dockerConfigProvider
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func (d *CachingDockerConfigProvider) Provide() DockerConfig {
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d.mu.Lock()
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defer d.mu.Unlock()
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// If the cache hasn't expired, return our cache
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if time.Now().Before(d.expiration) {
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return d.cacheDockerConfig
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}
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glog.V(2).Infof("Refreshing cache for provider: %v", reflect.TypeOf(d.Provider).String())
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d.cacheDockerConfig = d.Provider.Provide()
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d.expiration = time.Now().Add(d.Lifetime)
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return d.cacheDockerConfig
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}
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