Implement --follow entirely correctly for the journald log reader, such
that it exits immediately upon reading back the last log message written
to the journal before the logger was closed. The impossibility of doing
so has been slightly exaggerated.
Signed-off-by: Cory Snider <csnider@mirantis.com>
Fix journald and logfile-powered (jsonfile, local) log readers
incorrectly filtering out messages with timestamps < Since which were
preceded by a message with a timestamp >= Since.
Signed-off-by: Cory Snider <csnider@mirantis.com>
Careful management of the journal read pointer is sufficient to ensure
that no entry is read more than once.
Unit test the journald logger without requiring a running journald by
using the systemd-journal-remote command to write arbitrary entries to
journal files.
Signed-off-by: Cory Snider <csnider@mirantis.com>
1. Add integration tests for the ContainerLogs API call
Each test handle a distinct case of ContainerLogs output.
- Muxed stream, when container is started without tty
- Single stream, when container is started with tty
2. Add unit test for LogReader suite that tests concurrent logging
It checks that there are no race conditions when logging concurrently
from multiple goroutines.
Co-authored-by: Cory Snider <csnider@mirantis.com>
Signed-off-by: Cory Snider <csnider@mirantis.com>
Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
The refCounter used for sharing temporary decompressed log files and
tracking when the files can be deleted is keyed off the source file's
path. But the path of a log file is not stable: it is renamed on each
rotation. Consequently, when logging is configured with both rotation
and compression, multiple concurrent readers of a container's logs could
read logs out of order, see duplicates or decompress a log file which
has already been decompressed.
Replace refCounter with a new implementation, sharedTempFileConverter,
which is agnostic to the file path, keying off the source file's
identity instead. Additionally, sharedTempFileConverter handles the full
lifecycle of the temporary file, from creation to deletion. This is all
abstracted from the consumer: all the bookkeeping and cleanup is handled
behind the scenes when Close() is called on the returned reader value.
Only one file descriptor is used per temporary file, which is shared by
all readers.
A channel is used for concurrency control so that the lock can be
acquired inside a select statement. While not currently utilized, this
makes it possible to add support for cancellation to
sharedTempFileConverter in the future.
Signed-off-by: Cory Snider <csnider@mirantis.com>
Add an extensive test suite for validating the behavior of any
LogReader. Test the current LogFile-based implementations against it.
Signed-off-by: Cory Snider <csnider@mirantis.com>
Cory Snider