journald event logging

add the ability for podman to read and write events to journald instead
of just a logfile.  This can be controlled in libpod.conf with the
`events_logger` attribute of `journald` or `file`.  The default will be
set to `journald`.

Signed-off-by: baude <bbaude@redhat.com>

1 files changed, 131 insertions, 0 deletions

diff --git a/libpod/events/journal_linux.go b/libpod/events/journal_linux.go
new file mode 100644
index 000000000..e6b54db1d
--- /dev/null
+++ b/libpod/events/journal_linux.go
@@ -0,0 +1,131 @@
+package events
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/coreos/go-systemd/journal"
+	"github.com/coreos/go-systemd/sdjournal"
+	"github.com/pkg/errors"
+)
+
+// EventJournalD is the journald implementation of an eventer
+type EventJournalD struct {
+	options EventerOptions
+}
+
+// Write to journald
+func (e EventJournalD) Write(ee Event) error {
+	m := make(map[string]string)
+	m["SYSLOG_IDENTIFIER"] = "podman"
+	m["PODMAN_EVENT"] = ee.Status.String()
+	m["PODMAN_TYPE"] = ee.Type.String()
+	m["PODMAN_TIME"] = ee.Time.Format(time.RFC3339Nano)
+
+	// Add specialized information based on the podman type
+	switch ee.Type {
+	case Image:
+		m["PODMAN_NAME"] = ee.Name
+		m["PODMAN_ID"] = ee.ID
+	case Container, Pod:
+		m["PODMAN_IMAGE"] = ee.Image
+		m["PODMAN_NAME"] = ee.Name
+		m["PODMAN_ID"] = ee.ID
+	case Volume:
+		m["PODMAN_NAME"] = ee.Name
+	}
+	return journal.Send(fmt.Sprintf("%s", ee.ToHumanReadable()), journal.PriInfo, m)
+}
+
+// Read reads events from the journal and sends qualified events to the event channel
+func (e EventJournalD) Read(options ReadOptions) error {
+	eventOptions, err := generateEventOptions(options.Filters, options.Since, options.Until)
+	if err != nil {
+		return errors.Wrapf(err, "failed to generate event options")
+	}
+	podmanJournal := sdjournal.Match{Field: "SYSLOG_IDENTIFIER", Value: "podman"} //nolint
+	j, err := sdjournal.NewJournal()                                              //nolint
+	if err != nil {
+		return err
+	}
+	if err := j.AddMatch(podmanJournal.String()); err != nil {
+		return errors.Wrap(err, "failed to add 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")
+		}
+	}
+	// the api requires a next|prev before getting a cursor
+	if _, err := j.Next(); err != nil {
+		return err
+	}
+	prevCursor, err := j.GetCursor()
+	if err != nil {
+		return err
+	}
+	defer close(options.EventChannel)
+	for {
+		if _, err := j.Next(); err != nil {
+			return err
+		}
+		newCursor, err := j.GetCursor()
+		if err != nil {
+			return err
+		}
+		if prevCursor == newCursor {
+			if len(options.Until) > 0 || !options.Stream {
+				break
+			}
+			_ = j.Wait(sdjournal.IndefiniteWait) //nolint
+			continue
+		}
+		prevCursor = newCursor
+		entry, err := j.GetEntry()
+		if err != nil {
+			return err
+		}
+		newEvent, err := newEventFromJournalEntry(entry)
+		if err != nil {
+			return err
+		}
+		include := true
+		for _, filter := range eventOptions {
+			include = include && filter(newEvent)
+		}
+		if include {
+			options.EventChannel <- newEvent
+		}
+	}
+	return nil
+
+}
+
+func newEventFromJournalEntry(entry *sdjournal.JournalEntry) (*Event, error) { //nolint
+	newEvent := Event{}
+	eventType, err := StringToType(entry.Fields["PODMAN_TYPE"])
+	if err != nil {
+		return nil, err
+	}
+	eventTime, err := time.Parse(time.RFC3339Nano, entry.Fields["PODMAN_TIME"])
+	if err != nil {
+		return nil, err
+	}
+	eventStatus, err := StringToStatus(entry.Fields["PODMAN_EVENT"])
+	if err != nil {
+		return nil, err
+	}
+	newEvent.Type = eventType
+	newEvent.Time = eventTime
+	newEvent.Status = eventStatus
+	newEvent.Name = entry.Fields["PODMAN_NAME"]
+
+	switch eventType {
+	case Container, Pod:
+		newEvent.ID = entry.Fields["PODMAN_ID"]
+		newEvent.Image = entry.Fields["PODMAN_IMAGE"]
+	case Image:
+		newEvent.ID = entry.Fields["PODMAN_ID"]
+	}
+	return &newEvent, nil
+}