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endpoint: Receiver.Receive: save a peek of recv stream to a temporary dataset if placeholder + encryption recv -F error is detected
This commit is contained in:
Christian Schwarz
parent
05a39eaddf
commit
42ffca09db
@ -2,17 +2,17 @@
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package endpoint
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import (
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"bufio"
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"bytes"
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"context"
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"fmt"
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"io"
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"path"
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"strings"
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"sync"
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"github.com/pkg/errors"
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"github.com/zrepl/zrepl/replication/logic/pdu"
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"github.com/zrepl/zrepl/util/chainedio"
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"github.com/zrepl/zrepl/util/chainlock"
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"github.com/zrepl/zrepl/util/envconst"
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"github.com/zrepl/zrepl/util/semaphore"
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@ -812,14 +812,21 @@ func (s *Receiver) Receive(ctx context.Context, req *pdu.ReceiveReq, receive io.
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}
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defer guard.Release()
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log.Info("peeking 1M ahead")
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var peek bytes.Buffer
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var MaxPeek = envconst.Int64("ZREPL_ENDPOINT_RECV_PEEK_SIZE", 1<<20)
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if _, err := io.Copy(&peek, io.LimitReader(receive, MaxPeek)); err != nil {
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log.WithError(err).Error("cannot read peek-buffer from send stream")
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}
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var peekCopy bytes.Buffer
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if n, err := peekCopy.Write(peek.Bytes()); err != nil || n != peek.Len() {
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panic(peek.Len())
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}
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log.WithField("opts", fmt.Sprintf("%#v", recvOpts)).Debug("start receive command")
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snapFullPath := to.FullPath(lp.ToString())
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if err := zfs.ZFSRecv(ctx, lp.ToString(), to, receive, recvOpts); err != nil {
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log.
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WithError(err).
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WithField("opts", fmt.Sprintf("%#v", recvOpts)).
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Error("zfs receive failed")
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if err := zfs.ZFSRecv(ctx, lp.ToString(), to, chainedio.NewChainedReader(&peek, receive), recvOpts); err != nil {
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// best-effort rollback of placeholder state if the recv didn't start
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_, resumableStatePresent := err.(*zfs.RecvFailedWithResumeTokenErr)
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@ -838,21 +845,56 @@ func (s *Receiver) Receive(ctx context.Context, req *pdu.ReceiveReq, receive io.
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// deal with failing initial encrypted send & recv
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if _, ok := err.(*zfs.RecvDestroyOrOverwriteEncryptedErr); ok && ph.IsPlaceholder && placeholderRestored {
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msg := `cannot replace placeholder filesystem with incoming send stream: OpenZFS does not support replacing encrypted filesystems using zfs receive -F`
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long := `
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It is very likely that you are encountering this error because you changed the sending job's list of filesystems.
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Replication should start working again once you change those settings back to what they were before.
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You can learn more about zrepl's placeholder filesystems at https://zrepl.github.io/configuration/overview.html#replication-placeholder-property
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If you would like to see improvements to this situation, please open an issue at https://github.com/zrepl/zrepl/issues , citing the previous error messages
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`
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msg := `cannot automatically replace placeholder filesystem with incoming send stream - please see receive-side log for details`
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err := errors.New(msg)
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log.Error(msg)
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s := bufio.NewScanner(strings.NewReader(long))
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for s.Scan() {
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log.Error(strings.TrimSpace(s.Text()))
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log.Error(`zrepl creates placeholder filesystems on the receiving side of a replication to match the sending side's dataset hierarchy`)
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log.Error(`zrepl uses zfs receive -F to replace those placeholders with incoming full sends`)
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log.Error(`OpenZFS native encryption prohibits zfs receive -F for encrypted filesystems`)
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log.Error(`the current zrepl placeholder filesystem concept is thus incompatible with OpenZFS native encryption`)
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tempStartFullRecvFS := lp.Copy().ToString() + ".zrepl.initial-recv"
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tempStartFullRecvFSDP, dpErr := zfs.NewDatasetPath(tempStartFullRecvFS)
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if dpErr != nil {
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log.WithError(dpErr).Error("cannot determine temporary filesystem name for initial encrypted recv workaround")
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return nil, err // yes, err, not dpErr
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}
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return nil, errors.New(msg)
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log := log.WithField("temp_recv_fs", tempStartFullRecvFS)
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log.Error(`as a workaround, zrepl will now attempt to re-receive the beginning of the stream into a temporary filesystem temp_recv_fs`)
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log.Error(`if that step succeeds: shut down zrepl and use 'zfs rename' to swap temp_recv_fs with local_fs, then restart zrepl`)
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log.Error(`replication will then resume using resumable send+recv`)
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tempPH, phErr := zfs.ZFSGetFilesystemPlaceholderState(ctx, tempStartFullRecvFSDP)
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if phErr != nil {
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log.WithError(phErr).Error("cannot determine placeholder state of temp_recv_fs")
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return nil, err // yes, err, not dpErr
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}
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if tempPH.FSExists {
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log.Error("temp_recv_fs already exists, assuming a (partial) initial recv to that filesystem has already been done")
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return nil, err
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}
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recvOpts.RollbackAndForceRecv = false
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recvOpts.SavePartialRecvState = true
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rerecvErr := zfs.ZFSRecv(ctx, tempStartFullRecvFS, to, chainedio.NewChainedReader(&peekCopy), recvOpts)
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if _, isResumable := rerecvErr.(*zfs.RecvFailedWithResumeTokenErr); rerecvErr == nil || isResumable {
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log.Error("completed re-receive into temporary filesystem temp_recv_fs, now shut down zrepl and use zfs rename to swap temp_recv_fs with local_fs")
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} else {
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log.WithError(rerecvErr).Error("failed to receive the beginning of the stream into temporary filesystem temp_recv_fs")
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log.Error("we advise you to collect the error log and current configuration, open an issue on GitHub, and revert to your previous configuration in the meantime")
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}
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log.Error(`if you would like to see improvements to this situation, please open an issue on GitHub`)
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return nil, err
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}
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log.
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WithError(err).
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WithField("opts", fmt.Sprintf("%#v", recvOpts)).
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Error("zfs receive failed")
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return nil, err
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}
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43
util/chainedio/chainedio_readcloser.go
Normal file
43
util/chainedio/chainedio_readcloser.go
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@ -0,0 +1,43 @@
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package chainedio
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import "io"
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type ChainedReadCloser struct {
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readers []io.Reader
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curReader int
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}
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func NewChainedReader(reader ...io.Reader) *ChainedReadCloser {
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return &ChainedReadCloser{
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readers: reader,
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curReader: 0,
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}
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}
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func (c *ChainedReadCloser) Read(buf []byte) (n int, err error) {
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n = 0
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for c.curReader < len(c.readers) {
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n, err = c.readers[c.curReader].Read(buf)
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if err == io.EOF {
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c.curReader++
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continue
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}
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break
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}
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if c.curReader == len(c.readers) {
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err = io.EOF // actually, there was no gap
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}
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return
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}
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func (c *ChainedReadCloser) Close() error {
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for _, r := range c.readers {
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if c, ok := r.(io.Closer); ok {
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c.Close() // TODO debug log error?
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}
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}
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return nil
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}
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@ -1,34 +0,0 @@
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package chainedio
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import "io"
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type ChainedReader struct {
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Readers []io.Reader
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curReader int
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}
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func NewChainedReader(reader ...io.Reader) *ChainedReader {
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return &ChainedReader{
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Readers: reader,
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curReader: 0,
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}
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}
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func (c *ChainedReader) Read(buf []byte) (n int, err error) {
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n = 0
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for c.curReader < len(c.Readers) {
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n, err = c.Readers[c.curReader].Read(buf)
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if err == io.EOF {
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c.curReader++
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continue
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}
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break
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}
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if c.curReader == len(c.Readers) {
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err = io.EOF // actually, there was no gap
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}
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return
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}
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