*: support --log-output=discard

Signed-off-by: Gyuho Lee <gyuhox@gmail.com>

CHANGELOG-3.4.md

@@ -144,6 +144,7 @@ See [security doc](https://github.com/coreos/etcd/blob/master/Documentation/op-g
   - e.g. `--logger=zap --log-output=default` will log server operations with [JSON-encoded format](TODO) and writes logs to `os.Stderr` (detect systemd journald TODO).
   - e.g. `--logger=zap --log-output=stderr` will log server operations with [JSON-encoded format](TODO) and writes logs to `os.Stderr` (bypass journald TODO).
   - e.g. `--logger=zap --log-output=stdout` will log server operations with [JSON-encoded format](TODO) and writes logs to `os.Stdout` (bypass journald TODO).
+  - e.g. `--logger=zap --log-output=discard` will discard all server logs.
 
 ### Added: `embed`
 

embed/config.go

@@ -421,18 +421,25 @@ func (cfg *Config) setupLogging() error {
 				lcfg.OutputPaths = []string{"stderr"}
 				lcfg.ErrorOutputPaths = []string{"stderr"}
 			}
+
 		case "stderr":
 			lcfg.OutputPaths = []string{"stderr"}
 			lcfg.ErrorOutputPaths = []string{"stderr"}
+
 		case "stdout":
 			lcfg.OutputPaths = []string{"stdout"}
 			lcfg.ErrorOutputPaths = []string{"stdout"}
-		case "io-discard": // only for testing
+
+		case "discard": // only for testing
+			lcfg.OutputPaths = []string{}
+			lcfg.ErrorOutputPaths = []string{}
 			ignoreLog = true
+
 		default:
 			lcfg.OutputPaths = []string{cfg.LogOutput}
 			lcfg.ErrorOutputPaths = []string{cfg.LogOutput}
 		}
+
 		if cfg.Debug {
 			lcfg.Level = zap.NewAtomicLevelAt(zap.DebugLevel)
 			grpc.EnableTracing = true

embed/config_test.go

@@ -41,7 +41,7 @@ func TestConfigFileOtherFields(t *testing.T) {
 		ptls,
 		true,
 		"zap",
-		"io-discard",
+		"discard",
 		false,
 	}
 
@@ -157,7 +157,7 @@ func mustCreateCfgFile(t *testing.T, b []byte) *os.File {
 func TestAutoCompactionModeInvalid(t *testing.T) {
 	cfg := NewConfig()
 	cfg.Logger = "zap"
-	cfg.LogOutput = "io-discard"
+	cfg.LogOutput = "discard"
 	cfg.Debug = false
 	cfg.AutoCompactionMode = "period"
 	err := cfg.Validate()

integration/embed_test.go

@@ -53,7 +53,7 @@ func TestEmbedEtcd(t *testing.T) {
 	for i := range tests {
 		tests[i].cfg = *embed.NewConfig()
 		tests[i].cfg.Logger = "zap"
-		tests[i].cfg.LogOutput = "io-discard"
+		tests[i].cfg.LogOutput = "discard"
 		tests[i].cfg.Debug = false
 
 	}
@@ -180,7 +180,7 @@ func newEmbedURLs(secure bool, n int) (urls []url.URL) {
 
 func setupEmbedCfg(cfg *embed.Config, curls []url.URL, purls []url.URL) {
 	cfg.Logger = "zap"
-	cfg.LogOutput = "io-discard"
+	cfg.LogOutput = "discard"
 	cfg.Debug = false
 
 	cfg.ClusterState = "new"

snapshot/member_test.go

@@ -64,7 +64,7 @@ func TestSnapshotV3RestoreMultiMemberAdd(t *testing.T) {
 
 	cfg := embed.NewConfig()
 	cfg.Logger = "zap"
-	cfg.LogOutput = "io-discard"
+	cfg.LogOutput = "discard"
 	cfg.Debug = false
 	cfg.Name = "3"
 	cfg.InitialClusterToken = testClusterTkn

snapshot/v3_snapshot_test.go

@@ -44,7 +44,7 @@ func TestSnapshotV3RestoreSingle(t *testing.T) {
 
 	cfg := embed.NewConfig()
 	cfg.Logger = "zap"
-	cfg.LogOutput = "io-discard"
+	cfg.LogOutput = "discard"
 	cfg.Debug = false
 	cfg.Name = "s1"
 	cfg.InitialClusterToken = testClusterTkn
@@ -153,7 +153,7 @@ func createSnapshotFile(t *testing.T, kvs []kv) string {
 
 	cfg := embed.NewConfig()
 	cfg.Logger = "zap"
-	cfg.LogOutput = "io-discard"
+	cfg.LogOutput = "discard"
 	cfg.Debug = false
 	cfg.Name = "default"
 	cfg.ClusterState = "new"
@@ -220,7 +220,7 @@ func restoreCluster(t *testing.T, clusterN int, dbPath string) (
 	for i := 0; i < clusterN; i++ {
 		cfg := embed.NewConfig()
 		cfg.Logger = "zap"
-		cfg.LogOutput = "io-discard"
+		cfg.LogOutput = "discard"
 		cfg.Debug = false
 		cfg.Name = fmt.Sprintf("%d", i)
 		cfg.InitialClusterToken = testClusterTkn