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sync_dns.go
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sync_dns.go
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package action
import (
"encoding/json"
"errors"
"fmt"
"path/filepath"
"sync"
"github.com/cloudfoundry/bosh-agent/agent/action/state"
boshplat "github.com/cloudfoundry/bosh-agent/platform"
boshsettings "github.com/cloudfoundry/bosh-agent/settings"
boshblob "github.com/cloudfoundry/bosh-utils/blobstore"
boshcrypto "github.com/cloudfoundry/bosh-utils/crypto"
bosherr "github.com/cloudfoundry/bosh-utils/errors"
boshlog "github.com/cloudfoundry/bosh-utils/logger"
boshuuid "github.com/cloudfoundry/bosh-utils/uuid"
)
const localDNSStateFilename = "records.json"
type SyncDNS struct {
blobstore boshblob.DigestBlobstore
settingsService boshsettings.Service
platform boshplat.Platform
logger boshlog.Logger
logTag string
lock *sync.Mutex
}
func NewSyncDNS(blobstore boshblob.DigestBlobstore, settingsService boshsettings.Service, platform boshplat.Platform, logger boshlog.Logger) SyncDNS {
return SyncDNS{
blobstore: blobstore,
settingsService: settingsService,
platform: platform,
logger: logger,
lock: &sync.Mutex{},
logTag: "Sync DNS action",
}
}
func (a SyncDNS) IsAsynchronous(_ ProtocolVersion) bool {
return false
}
func (a SyncDNS) IsPersistent() bool {
return false
}
func (a SyncDNS) IsLoggable() bool {
return true
}
func (a SyncDNS) Resume() (interface{}, error) {
return nil, errors.New("not supported")
}
func (a SyncDNS) Cancel() error {
return errors.New("not supported")
}
func (a SyncDNS) Run(blobID string, multiDigest boshcrypto.MultipleDigest, version uint64) (string, error) {
if !a.needsUpdateWithLock(version) {
return "synced", nil
}
filePath, err := a.blobstore.Get(blobID, multiDigest)
if err != nil {
return "", bosherr.WrapErrorf(err, "getting %s from blobstore", blobID)
}
fs := a.platform.GetFs()
defer func() {
err = fs.RemoveAll(filePath)
if err != nil {
a.logger.Error(a.logTag, fmt.Sprintf("Failed to remove dns blob file at path '%s'", filePath))
}
}()
contents, err := fs.ReadFile(filePath)
if err != nil {
return "", bosherr.WrapErrorf(err, "reading %s from blobstore", filePath)
}
a.lock.Lock()
defer a.lock.Unlock()
syncDNSState := a.createSyncDNSState()
if !syncDNSState.NeedsUpdate(version) {
return "synced", nil
}
dnsRecords := boshsettings.DNSRecords{}
if err := json.Unmarshal(contents, &dnsRecords); err != nil {
return "", bosherr.WrapError(err, "unmarshalling DNS records")
}
if dnsRecords.Version != version {
return "", bosherr.Error("version from unpacked dns blob does not match version supplied by director")
}
err = a.platform.SaveDNSRecords(dnsRecords, a.settingsService.GetSettings().AgentID)
if err != nil {
return "", bosherr.WrapError(err, "saving DNS records")
}
err = syncDNSState.SaveState(contents)
if err != nil {
return "", bosherr.WrapError(err, "saving local DNS state")
}
return "synced", nil
}
func (a SyncDNS) createSyncDNSState() state.SyncDNSState {
stateFilePath := filepath.Join(a.platform.GetDirProvider().InstanceDNSDir(), localDNSStateFilename)
return state.NewSyncDNSState(a.platform, stateFilePath, boshuuid.NewGenerator())
}
func (a SyncDNS) needsUpdateWithLock(version uint64) bool {
a.lock.Lock()
defer a.lock.Unlock()
return a.createSyncDNSState().NeedsUpdate(version)
}