backport of commit 57b6b74283 (#24470)

Co-authored-by: Hamid Ghaf <83242695+hghaf099@users.noreply.github.com>

changelog/24280.txt

@@ -0,0 +1,3 @@
+```release-note:improvement
+command/server: display logs on startup immediately if disable-gated-logs flag is set
+```

command/agent.go

@@ -223,6 +223,11 @@ func (c *AgentCommand) Run(args []string) int {
 		InferLevelsWithTimestamp: true,
 	})
 
+	// release log gate if the disable-gated-logs flag is set
+	if c.logFlags.flagDisableGatedLogs {
+		c.logGate.Flush()
+	}
+
 	infoKeys := make([]string, 0, 10)
 	info := make(map[string]string)
 	info["log level"] = config.LogLevel

command/commands.go

@@ -148,6 +148,8 @@ const (
 	flagNameDisableRedirects = "disable-redirects"
 	// flagNameCombineLogs is used to specify whether log output should be combined and sent to stdout
 	flagNameCombineLogs = "combine-logs"
+	// flagDisableGatedLogs is used to disable gated logs and immediately show the vault logs as they become available
+	flagDisableGatedLogs = "disable-gated-logs"
 	// flagNameLogFile is used to specify the path to the log file that Vault should use for logging
 	flagNameLogFile = "log-file"
 	// flagNameLogRotateBytes is the flag used to specify the number of bytes a log file should be before it is rotated.

command/log_flags.go

@@ -15,6 +15,7 @@ import (
 // logFlags are the 'log' related flags that can be shared across commands.
 type logFlags struct {
 	flagCombineLogs       bool
+	flagDisableGatedLogs  bool
 	flagLogLevel          string
 	flagLogFormat         string
 	flagLogFile           string
@@ -41,6 +42,13 @@ func (f *FlagSet) addLogFlags(l *logFlags) {
 		Hidden:  true,
 	})
 
+	f.BoolVar(&BoolVar{
+		Name:    flagDisableGatedLogs,
+		Target:  &l.flagDisableGatedLogs,
+		Default: false,
+		Hidden:  true,
+	})
+
 	f.StringVar(&StringVar{
 		Name:       flagNameLogLevel,
 		Target:     &l.flagLogLevel,

command/proxy.go

@@ -210,6 +210,11 @@ func (c *ProxyCommand) Run(args []string) int {
 	}
 	c.logger = l
 
+	// release log gate if the disable-gated-logs flag is set
+	if c.logFlags.flagDisableGatedLogs {
+		c.logGate.Flush()
+	}
+
 	infoKeys := make([]string, 0, 10)
 	info := make(map[string]string)
 	info["log level"] = config.LogLevel

command/server.go

@@ -1111,6 +1111,11 @@ func (c *ServerCommand) Run(args []string) int {
 	c.logger = l
 	c.allLoggers = append(c.allLoggers, l)
 
+	// flush logs right away if the server is started with the disable-gated-logs flag
+	if c.logFlags.flagDisableGatedLogs {
+		c.flushLog()
+	}
+
 	// reporting Errors found in the config
 	for _, cErr := range configErrors {
 		c.logger.Warn(cErr.String())