From 692559c8c5e52ecc5c636ed3d7d7aac6cf4490ed Mon Sep 17 00:00:00 2001
From: Paul Holzinger <paul.holzinger@web.de>
Date: Tue, 27 Oct 2020 13:33:37 +0100
Subject: Improve the journal event reading
Fix the AddMatch/SeekTail conflict. This prevents reading
unnecessary journal entries which could cause errors.
Also wrap the sdjournal errors to provide better error messages.
Fixes #8125
Signed-off-by: Paul Holzinger <paul.holzinger@web.de>
---
libpod/events/journal_linux.go | 48 +++++++++++++++++++++---------------------
1 file changed, 24 insertions(+), 24 deletions(-)
diff --git a/libpod/events/journal_linux.go b/libpod/events/journal_linux.go
index 5d17a85b4..5e3be8009 100644
--- a/libpod/events/journal_linux.go
+++ b/libpod/events/journal_linux.go
@@ -69,35 +69,39 @@ func (e EventJournalD) Read(ctx context.Context, options ReadOptions) error {
if err != nil {
return errors.Wrapf(err, "failed to generate event options")
}
- j, err := sdjournal.NewJournal() //nolint
+ j, err := sdjournal.NewJournal()
if err != nil {
return err
}
- // TODO AddMatch and Seek seem to conflict
- // Issue filed upstream -> https://github.com/coreos/go-systemd/issues/315
- // Leaving commented code in case upstream fixes things
- //podmanJournal := sdjournal.Match{Field: "SYSLOG_IDENTIFIER", Value: "podman"} //nolint
- //if err := j.AddMatch(podmanJournal.String()); err != nil {
- // return errors.Wrap(err, "failed to add filter for event log")
- //}
+
+ // match only podman journal entries
+ podmanJournal := sdjournal.Match{Field: "SYSLOG_IDENTIFIER", Value: "podman"}
+ if err := j.AddMatch(podmanJournal.String()); err != nil {
+ return errors.Wrap(err, "failed to add journal filter for event log")
+ }
+
if len(options.Since) == 0 && len(options.Until) == 0 && options.Stream {
if err := j.SeekTail(); err != nil {
return errors.Wrap(err, "failed to seek end of journal")
}
- } else {
- podmanJournal := sdjournal.Match{Field: "SYSLOG_IDENTIFIER", Value: "podman"} //nolint
- if err := j.AddMatch(podmanJournal.String()); err != nil {
- return errors.Wrap(err, "failed to add filter for event log")
+ // After SeekTail calling Next moves to a random entry.
+ // To prevent this we have to call Previous first.
+ // see: https://bugs.freedesktop.org/show_bug.cgi?id=64614
+ if _, err := j.Previous(); err != nil {
+ return errors.Wrap(err, "failed to move journal cursor to previous entry")
}
}
+
// the api requires a next|prev before getting a cursor
if _, err := j.Next(); err != nil {
- return err
+ return errors.Wrap(err, "failed to move journal cursor to next entry")
}
+
prevCursor, err := j.GetCursor()
if err != nil {
- return err
+ return errors.Wrap(err, "failed to get journal cursor")
}
+
for {
select {
case <-ctx.Done():
@@ -106,30 +110,26 @@ func (e EventJournalD) Read(ctx context.Context, options ReadOptions) error {
default:
// fallthrough
}
+
if _, err := j.Next(); err != nil {
- return err
+ return errors.Wrap(err, "failed to move journal cursor to next entry")
}
newCursor, err := j.GetCursor()
if err != nil {
- return err
+ return errors.Wrap(err, "failed to get journal cursor")
}
if prevCursor == newCursor {
if len(options.Until) > 0 || !options.Stream {
break
}
- _ = j.Wait(sdjournal.IndefiniteWait) //nolint
+ _ = j.Wait(sdjournal.IndefiniteWait)
continue
}
prevCursor = newCursor
+
entry, err := j.GetEntry()
if err != nil {
- return err
- }
- // TODO this keeps us from feeding the podman event parser with
- // with regular journal content; it can be removed if the above
- // problem with AddMatch is resolved.
- if entry.Fields["PODMAN_EVENT"] == "" {
- continue
+ return errors.Wrap(err, "failed to read journal entry")
}
newEvent, err := newEventFromJournalEntry(entry)
if err != nil {
--
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