Add experiment system + events experiment (#18682)

command/server.go

@@ -36,6 +36,7 @@ import (
 	"github.com/hashicorp/vault/command/server"
 	"github.com/hashicorp/vault/helper/builtinplugins"
 	"github.com/hashicorp/vault/helper/constants"
+	"github.com/hashicorp/vault/helper/experiments"
 	loghelper "github.com/hashicorp/vault/helper/logging"
 	"github.com/hashicorp/vault/helper/metricsutil"
 	"github.com/hashicorp/vault/helper/namespace"
@@ -116,6 +117,7 @@ type ServerCommand struct {
 
 	flagConfigs            []string
 	flagRecovery           bool
+	flagExperiments        []string
 	flagDev                bool
 	flagDevTLS             bool
 	flagDevTLSCertDir      string
@@ -204,6 +206,17 @@ func (c *ServerCommand) Flags() *FlagSets {
 			"Using a recovery operation token, \"sys/raw\" API can be used to manipulate the storage.",
 	})
 
+	f.StringSliceVar(&StringSliceVar{
+		Name:       "experiment",
+		Target:     &c.flagExperiments,
+		Completion: complete.PredictSet(experiments.ValidExperiments()...),
+		Usage: "Name of an experiment to enable. Experiments should NOT be used in production, and " +
+			"the associated APIs may have backwards incompatible changes between releases. This " +
+			"flag can be specified multiple times to specify multiple experiments. This can also be " +
+			fmt.Sprintf("specified via the %s environment variable as a comma-separated list. ", EnvVaultExperiments) +
+			"Valid experiments are: " + strings.Join(experiments.ValidExperiments(), ", "),
+	})
+
 	f = set.NewFlagSet("Dev Options")
 
 	f.BoolVar(&BoolVar{
@@ -1105,6 +1118,11 @@ func (c *ServerCommand) Run(args []string) int {
 		}
 	}
 
+	if err := server.ExperimentsFromEnvAndCLI(config, EnvVaultExperiments, c.flagExperiments); err != nil {
+		c.UI.Error(err.Error())
+		return 1
+	}
+
 	// If mlockall(2) isn't supported, show a warning. We disable this in dev
 	// because it is quite scary to see when first using Vault. We also disable
 	// this if the user has explicitly disabled mlock in configuration.
@@ -1173,6 +1191,12 @@ func (c *ServerCommand) Run(args []string) int {
 	info[key] = strings.Join(envVarKeys, ", ")
 	infoKeys = append(infoKeys, key)
 
+	if len(config.Experiments) != 0 {
+		expKey := "experiments"
+		info[expKey] = strings.Join(config.Experiments, ", ")
+		infoKeys = append(infoKeys, expKey)
+	}
+
 	barrierSeal, barrierWrapper, unwrapSeal, seals, sealConfigError, err := setSeal(c, config, infoKeys, info)
 	// Check error here
 	if err != nil {
@@ -2637,6 +2661,7 @@ func createCoreConfig(c *ServerCommand, config *server.Config, backend physical.
 		License:                        config.License,
 		LicensePath:                    config.LicensePath,
 		DisableSSCTokens:               config.DisableSSCTokens,
+		Experiments:                    config.Experiments,
 	}
 
 	if c.flagDev {