we never actually compressed any files, since we only looked at
the extension:
* if it was 'zst' (which was always true for newly rotated files), we
would not compress it
* even if it was not 'zst', we compressed it inplace, never adding '.zst'
(possibly compressing them multiple times as zstd)
now we add new rotated files simply as '.X' and add a 'target' to the
compress fn, where we rename it to (but now we have to unlink the source
path)
Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
The first rotation is normally the one still opened by one or more
processes for writing, so it must NOT be replaced, removed, ..., as
this then makes the remaining logging, until those processes are
noticed that they should reopen the logfile due to rotation, goes
into nirvana, which is far from ideal for a log.
Only rotating (renaming) is OK for this active file, as this does not
invalidates the file and keeps open FDs intact.
So start compressing with the second rotation, which should be clear
to use, as all writers must have been told to reopen the log during
the last rotation, reopen is a fast operation and normally triggered
at least day ago (at least if one did not dropped the state file
manually), so we are fine to archive that one for real.
If we plan to allow faster rotation the whole rotation+reopen should
be locked, so that we can guarantee that all writers switched over,
but this is unlikely to be needed.
Again, this is was logrotate sanely does by default since forever.
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
this is not the job of logrotate, and the real 20+ years battle
tested log rotate binary does not do so either as it's actually
pretty dangerous.
If we "replace" the file we break any logger which already opened a
new one here, e.g., a dameon starting up, and thus that writer would
log to nirvana.
It's the job of a logger to create a file if not existing, it makes
no sense to do it here.
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
this is a helper to rotate and iterate over log files
there is an iterator for open filehandles as well as
only the filename
also it has the possibilty to rotate them
for compression, zstd is used
Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
