libpod/events: refactor to eliminate unused code

Shuffle the code around to eliminate "unused" warnings when linting
with various GOOS and build tags.

The only change in functionality should be that now NewEventer
returns ErrNoJournaldLogging (rather than "unknown event logger type")
on freebsd when journald is requested.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

libpod/events/default_journal.go

@@ -0,0 +1,6 @@
+//go:build systemd && linux
+
+package events
+
+// DefaultEventerType is journald when systemd is available.
+const DefaultEventerType = Journald

libpod/events/default_logfile.go

@@ -0,0 +1,7 @@
+//go:build !systemd || !linux
+
+package events
+
+// DefaultEventerType is logfile when systemd is not present
+// or not supported.
+const DefaultEventerType = LogFile

libpod/events/events.go

@@ -98,16 +98,6 @@ func (e *Event) ToHumanReadable(truncate bool) string {
 	return humanFormat
 }
 
-// newEventFromJSONString takes stringified json and converts
-// it to an event
-func newEventFromJSONString(event string) (*Event, error) {
-	e := new(Event)
-	if err := json.Unmarshal([]byte(event), e); err != nil {
-		return nil, err
-	}
-	return e, nil
-}
-
 // String converts a Type to a string
 func (t Type) String() string {
 	return string(t)

libpod/events/events_freebsd.go

@@ -1,21 +0,0 @@
-package events
-
-import (
-	"fmt"
-	"strings"
-
-	"github.com/sirupsen/logrus"
-)
-
-// NewEventer creates an eventer based on the eventer type
-func NewEventer(options EventerOptions) (Eventer, error) {
-	logrus.Debugf("Initializing event backend %s", options.EventerType)
-	switch EventerType(strings.ToLower(options.EventerType)) {
-	case LogFile:
-		return EventLogFile{options}, nil
-	case Null:
-		return newNullEventer(), nil
-	default:
-		return nil, fmt.Errorf("unknown event logger type: %s", strings.ToLower(options.EventerType))
-	}
-}

libpod/events/events_supported.go

@@ -1,6 +1,9 @@
+//go:build linux || freebsd
+
 package events
 
 import (
+	"encoding/json"
 	"fmt"
 	"strings"
 
@@ -21,3 +24,19 @@ func NewEventer(options EventerOptions) (Eventer, error) {
 		return nil, fmt.Errorf("unknown event logger type: %s", strings.ToLower(options.EventerType))
 	}
 }
+
+// newEventFromJSONString takes stringified json and converts
+// it to an event
+func newEventFromJSONString(event string) (*Event, error) {
+	e := new(Event)
+	if err := json.Unmarshal([]byte(event), e); err != nil {
+		return nil, err
+	}
+	return e, nil
+}
+
+// newNullEventer returns a new null eventer.  You should only do this for
+// the purposes of internal libpod testing.
+func newNullEventer() Eventer {
+	return EventToNull{}
+}

libpod/events/filters.go

@@ -1,3 +1,5 @@
+//go:build linux || freebsd
+
 package events
 
 import (

libpod/events/journal_linux.go

@@ -17,9 +17,6 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
-// DefaultEventerType is journald when systemd is available
-const DefaultEventerType = Journald
-
 // EventJournalD is the journald implementation of an eventer
 type EventJournalD struct {
 	options EventerOptions

libpod/events/journal_unsupported.go

@@ -1,10 +1,7 @@
-//go:build !systemd
+//go:build (linux && !systemd) || freebsd
 
 package events
 
-// DefaultEventerType is logfile when systemd is not present
-const DefaultEventerType = LogFile
-
 // newJournalDEventer always returns an error if libsystemd not found
 func newJournalDEventer(options EventerOptions) (Eventer, error) {
 	return nil, ErrNoJournaldLogging

libpod/events/nullout.go

@@ -19,12 +19,6 @@ func (e EventToNull) Read(ctx context.Context, options ReadOptions) error {
 	return errors.New("cannot read events with the \"none\" backend")
 }
 
-// newNullEventer returns a new null eventer.  You should only do this for
-// the purposes of internal libpod testing.
-func newNullEventer() Eventer {
-	return EventToNull{}
-}
-
 // String returns a string representation of the logger
 func (e EventToNull) String() string {
 	return "none"