Add log rotation based on log size

Add new functions to logfile.go for rotating and truncating
the events log file once the log file and its contents
exceed the maximum size limit while keeping 50% of the
log file's content

Also add tests to verify log rotation and truncation

Signed-off-by: Niall Crowe <nicrowe@redhat.com>
Signed-off-by: Valentin Rothberg <vrothberg@redhat.com>

1 files changed, 65 insertions, 0 deletions

diff --git a/test/system/090-events.bats b/test/system/090-events.bats
index a0b0380a2..cac0a177c 100644
--- a/test/system/090-events.bats
+++ b/test/system/090-events.bats
@@ -129,3 +129,68 @@ EOF
     run cat $events_file
     is "$output" ".*\"Name\":\"$IMAGE" "test"
 }
+
+function _populate_events_file() {
+    # Create 100 duplicate entries to populate the events log file.
+    local events_file=$1
+    truncate --size=0 $events_file
+    for i in {0..99}; do
+    printf '{"Name":"busybox","Status":"pull","Time":"2022-04-06T11:26:42.7236679%02d+02:00","Type":"image","Attributes":null}\n' $i >> $events_file
+    done
+}
+
+@test "events log-file rotation" {
+    skip_if_remote "setting CONTAINERS_CONF logger options does not affect remote client"
+
+    # Make sure that the events log file is (not) rotated depending on the
+    # settings in containers.conf.
+
+    # Config without a limit
+    eventsFile=$PODMAN_TMPDIR/events.txt
+    _populate_events_file $eventsFile
+    containersConf=$PODMAN_TMPDIR/containers.conf
+    cat >$containersConf <<EOF
+[engine]
+events_logger="file"
+events_logfile_path="$eventsFile"
+EOF
+
+    # Create events *without* a limit and make sure that it has not been
+    # rotated/truncated.
+    contentBefore=$(head -n100 $eventsFile)
+    CONTAINERS_CONF=$containersConf run_podman run --rm $IMAGE true
+    contentAfter=$(head -n100 $eventsFile)
+    is "$contentBefore" "$contentAfter" "events file has not been rotated"
+
+    # Repopulate events file
+    rm $eventsFile
+    _populate_events_file $eventsFile
+
+    # Config with a limit
+    rm $containersConf
+    cat >$containersConf <<EOF
+[engine]
+events_logger="file"
+events_logfile_path="$eventsFile"
+# The limit of 4750 is the *exact* half of the inital events file.
+events_logfile_max_size=4750
+EOF
+
+    # Create events *with* a limit and make sure that it has been
+    # rotated/truncated.  Once rotated, the events file should only contain the
+    # second half of its previous events plus the new ones.
+    expectedContentAfterTruncation=$PODMAN_TMPDIR/truncated.txt
+
+    run_podman create $IMAGE
+    CONTAINERS_CONF=$containersConf run_podman rm $output
+    tail -n52 $eventsFile >> $expectedContentAfterTruncation
+
+    # Make sure the events file looks as expected.
+    is "$(cat $eventsFile)" "$(cat $expectedContentAfterTruncation)" "events file has been rotated"
+
+    # Make sure that `podman events` can read the file, and that it returns the
+    # same amount of events.  We checked the contents before.
+    CONTAINERS_CONF=$containersConf run_podman events --stream=false --since="2022-03-06T11:26:42.723667984+02:00"
+    is "$(wc -l <$eventsFile)" "$(wc -l <<<$output)" "all events are returned"
+    is "${lines[-2]}" ".* log-rotation $eventsFile"
+}