Add the Elasticsearch License in the log (elastic#15834)

* Add the ve Elasticsearch License in the log.

When the license callback is executed the license will be show in
the log at info level

CHANGELOG.asciidoc

@@ -13,6 +13,7 @@ https://github.com/elastic/beats/compare/v7.5.0...v7.5.1[View commits]
 
 - Fix `proxy_url` option in Elasticsearch output. {pull}14950[14950]
 - Fix bug with potential concurrent reads and writes from event.Meta map by Kafka output. {issue}14542[14542] {pull}14568[14568]
+- Fix license detection, when a beats successfully connect to Elasticsearch the detected license will be show in the log at info level. {pull}15834[15834]
 
 *Filebeat*
 

x-pack/functionbeat/function/beater/functionbeat.go

@@ -88,7 +88,7 @@ func (bt *Functionbeat) Run(b *beat.Beat) error {
 	}
 
 	if outputName == "elasticsearch" {
-		licenser.Enforce(logp.NewLogger("license"), b.Info.Name, licenser.BasicAndAboveOrTrial)
+		licenser.Enforce(b.Info.Name, licenser.BasicAndAboveOrTrial)
 	}
 
 	bt.log.Info("Functionbeat is running")

x-pack/libbeat/cmd/inject.go

@@ -6,7 +6,6 @@ package cmd
 
 import (
 	"github.com/elastic/beats/libbeat/cmd"
-	"github.com/elastic/beats/libbeat/logp"
 
 	// register central management
 	"github.com/elastic/beats/x-pack/libbeat/licenser"
@@ -16,10 +15,8 @@ import (
 	_ "github.com/elastic/beats/x-pack/libbeat/autodiscover/providers/aws/elb"
 )
 
-const licenseDebugK = "license"
-
 // AddXPack extends the given root folder with XPack features
 func AddXPack(root *cmd.BeatsRootCmd, name string) {
-	licenser.Enforce(logp.NewLogger(licenseDebugK), name, licenser.BasicAndAboveOrTrial)
+	licenser.Enforce(name, licenser.BasicAndAboveOrTrial)
 	root.AddCommand(genEnrollCmd(name, ""))
 }

x-pack/libbeat/licenser/es_callback.go

@@ -14,12 +14,17 @@ import (
 	"github.com/elastic/beats/libbeat/outputs/elasticsearch"
 )
 
+const licenseDebugK = "license"
+
 // Enforce setups the corresponding callbacks in libbeat to verify the license on the
 // remote elasticsearch cluster.
-func Enforce(log *logp.Logger, name string, checks ...CheckFunc) {
+func Enforce(name string, checks ...CheckFunc) {
 	name = strings.Title(name)
 
 	cb := func(client *elasticsearch.Client) error {
+		// Logger created earlier than this place are at risk of discarding any log statement.
+		log := logp.NewLogger(licenseDebugK)
+
 		fetcher := NewElasticFetcher(client)
 		license, err := fetcher.Fetch()
 
@@ -42,6 +47,8 @@ func Enforce(log *logp.Logger, name string, checks ...CheckFunc) {
 			)
 		}
 
+		log.Infof("Elasticsearch license: %s", license.Get())
+
 		return nil
 	}