Add event logging to libpod, even display to podman

In lipod, we now log major events that occurr.  These events
can be displayed using the `podman events` command. Each
event contains:

* Type (container, image, volume, pod...)
* Status (create, rm, stop, kill, ....)
* Timestamp in RFC3339Nano format
* Name (if applicable)
* Image (if applicable)

The format of the event and the varlink endpoint are to not
be considered stable until cockpit has done its enablement.

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

pkg/varlinkapi/events.go

@@ -0,0 +1,56 @@
+package varlinkapi
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/containers/libpod/cmd/podman/shared"
+	"github.com/containers/libpod/cmd/podman/varlink"
+	"github.com/containers/libpod/libpod/events"
+)
+
+// GetEvents is a remote endpoint to get events from the event log
+func (i *LibpodAPI) GetEvents(call iopodman.VarlinkCall, filter []string, since string, stream bool, until string) error {
+	var (
+		fromStart   bool
+		eventsError error
+		event       *events.Event
+	)
+	if call.WantsMore() {
+		call.Continues = true
+	}
+	filters, err := shared.GenerateEventOptions(filter, since, until)
+	if err != nil {
+		return call.ReplyErrorOccurred(err.Error())
+	}
+	if len(since) > 0 || len(until) > 0 {
+		fromStart = true
+	}
+	eventChannel := make(chan *events.Event)
+	go func() {
+		eventsError = i.Runtime.Events(fromStart, stream, filters, eventChannel)
+	}()
+	if eventsError != nil {
+		return call.ReplyErrorOccurred(err.Error())
+	}
+	for {
+		event = <-eventChannel
+		if event == nil {
+			call.Continues = false
+			break
+		}
+		call.ReplyGetEvents(iopodman.Event{
+			Id:     event.ID,
+			Image:  event.Image,
+			Name:   event.Name,
+			Status: fmt.Sprintf("%s", event.Status),
+			Time:   event.Time.Format(time.RFC3339Nano),
+			Type:   fmt.Sprintf("%s", event.Type),
+		})
+		if !call.Continues {
+			// For a one-shot on events, we break out here
+			break
+		}
+	}
+	return call.ReplyGetEvents(iopodman.Event{})
+}