Calling `wal.NewSegmentBufReader()` without any segments would cause a
`panic` resulting in prometheus crashing. This patch fixes the panic by
making segmentBufReader return a EOF if there are not segments.
This also means an empty checkpoint directory which should never be the
case unless it has been tampered with (or has issues due to the
underlying filesystem e.g. NFS) would be ignored by Prometheus and would
continue to run instead of the current behaviour which is to panic.
Fixes: https://github.com/prometheus/prometheus/issues/9605
Signed-off-by: Sunil Thaha <sthaha@redhat.com>
Snappy cannot encode records larger than ~3.7 GB and will panic if an
encoding is attempted. Check to make sure that the record is smaller
than this before encoding.
In the future, we could improve this behavior to still compress large
records (or break them up into smaller records), but this avoids the
panic for users with very large single scrape targets.
Signed-off-by: Chris Marchbanks <csmarchbanks@gmail.com>
Right now a new segment might be created unnecessarily if the
uncompressed record would not fit, but after compression (typically
reducing record size in half) it would.
Signed-off-by: Chris Marchbanks <csmarchbanks@gmail.com>
* Exports metric for WAL write errors
Signed-off-by: John McBride <jpmmcbride@gmail.com>
* Correct name for counter
Signed-off-by: John McBride <jpmmcbride@gmail.com>
* Move WAL write failure to wal.go
Signed-off-by: John McBride <jpmmcbride@gmail.com>
* WAL write fail metric moved to Log for external consumers
Signed-off-by: John McBride <jpmmcbride@gmail.com>
