Expose Null eventer and allow its use in the Podman CLI

We need this specifically for tests, but others may find it
useful if they don't explicitly need events and don't want the
performance implications of using them.

Signed-off-by: Matthew Heon <matthew.heon@pm.me>

5 files changed, 17 insertions, 6 deletions

diff --git a/docs/libpod.conf.5.md b/docs/libpod.conf.5.md
index 097d0764a..0bdba4593 100644
--- a/docs/libpod.conf.5.md
+++ b/docs/libpod.conf.5.md
@@ -99,7 +99,7 @@ libpod to manage containers.
   a slirp4netns network.  If "" is used then the binary is looked up using the $PATH environment variable.
 
 **events_logger**=""
-  Default method to use when logging events. Valid values are "journald" and "file".
+  Default method to use when logging events. Valid values are "file", "journald", and "null".
 
 **detach_keys**=""
   Keys sequence used for detaching a container
diff --git a/docs/podman.1.md b/docs/podman.1.md
index 02d15c197..7aa15019a 100644
--- a/docs/podman.1.md
+++ b/docs/podman.1.md
@@ -38,7 +38,7 @@ Path to where the cpu performance results should be written
 
 **--events-logger**=**type**
 
-Backend to use for storing events. Allowed values are **journald** and **file**.
+Backend to use for storing events. Allowed values are **file**, **journald**, and **null**.
 
 **--hooks-dir**=*path*
 
diff --git a/libpod/events/config.go b/libpod/events/config.go
index b9f01f3a5..96172d47b 100644
--- a/libpod/events/config.go
+++ b/libpod/events/config.go
@@ -14,6 +14,8 @@ const (
 	LogFile EventerType = iota
 	// Journald indicates journald should be used to log events
 	Journald EventerType = iota
+	// Null is a no-op events logger. It does not read or write events.
+	Null EventerType = iota
 )
 
 // Event describes the attributes of a libpod event
diff --git a/libpod/events/events.go b/libpod/events/events.go
index a898171c1..a80e97e90 100644
--- a/libpod/events/events.go
+++ b/libpod/events/events.go
@@ -16,11 +16,16 @@ var ErrNoJournaldLogging = errors.New("No support for journald logging")
 
 // String returns a string representation of EventerType
 func (et EventerType) String() string {
-	if et == LogFile {
+	switch et {
+	case LogFile:
 		return "file"
-
+	case Journald:
+		return "journald"
+	case Null:
+		return "null"
+	default:
+		return "invalid"
 	}
-	return "journald"
 }
 
 // IsValidEventer checks if the given string is a valid eventer type.
@@ -30,6 +35,8 @@ func IsValidEventer(eventer string) bool {
 		return true
 	case Journald.String():
 		return true
+	case Null.String():
+		return true
 	default:
 		return false
 	}
diff --git a/libpod/events/events_linux.go b/libpod/events/events_linux.go
index 11f309574..ffb100be8 100644
--- a/libpod/events/events_linux.go
+++ b/libpod/events/events_linux.go
@@ -18,8 +18,10 @@ func NewEventer(options EventerOptions) (eventer Eventer, err error) {
 		}
 	case strings.ToUpper(LogFile.String()):
 		eventer = EventLogFile{options}
+	case strings.ToUpper(Null.String()):
+		eventer = NewNullEventer()
 	default:
-		return eventer, errors.Errorf("unknown event logger type: %s", strings.ToUpper(options.EventerType))
+		return nil, errors.Errorf("unknown event logger type: %s", strings.ToUpper(options.EventerType))
 	}
 	return eventer, nil
 }