[8.12] Beat: Allow setting beat name in configuration (backport #12176)

changelogs/8.12.asciidoc

@@ -13,6 +13,7 @@ https://github.com/elastic/apm-server/compare/8.11\...8.12[View commits]
 ==== Breaking Changes
 - The unsupported apm_data_stream_migration ingest pipeline has been removed {pull}12102[12102].
 - "publish_ready" is always false in the "GET /" response until events are received by apm-server {pull}12150[12150]
+- Reverts a breaking change that ignored the beat name. This is visible in Stack Monitoring {pull}12176[12176]
 
 [float]
 ==== Bug fixes

internal/beatcmd/beat.go

@@ -102,14 +102,18 @@ func NewBeat(args BeatParams) (*Beat, error) {
 		return nil, err
 	}
 
+	beatName := cfg.Name
+	if beatName == "" {
+		beatName = hostname
+	}
 	b := &Beat{
 		Beat: beat.Beat{
 			Info: beat.Info{
 				Beat:            "apm-server",
 				ElasticLicensed: args.ElasticLicensed,
 				IndexPrefix:     "apm-server",
 				Version:         version.Version,
-				Name:            hostname,
+				Name:            beatName,
 				Hostname:        hostname,
 				StartTime:       time.Now(),
 				EphemeralID:     metricreport.EphemeralID(),

internal/beatcmd/beat_test.go

@@ -75,7 +75,7 @@ func TestRunMaxProcs(t *testing.T) {
 
 func TestRunnerParams(t *testing.T) {
 	calls := make(chan RunnerParams, 1)
-	b := newBeat(t, "output.console.enabled: true", func(args RunnerParams) (Runner, error) {
+	b := newBeat(t, "output.console.enabled: true\nname: my-custom-name", func(args RunnerParams) (Runner, error) {
 		calls <- args
 		return newNopRunner(args), nil
 	})
@@ -86,6 +86,7 @@ func TestRunnerParams(t *testing.T) {
 	assert.Equal(t, "apm-server", args.Info.Beat)
 	assert.Equal(t, version.Version, args.Info.Version)
 	assert.True(t, args.Info.ElasticLicensed)
+	assert.Equal(t, "my-custom-name", b.Beat.Info.Name)
 	assert.NotZero(t, args.Info.ID)
 	assert.NotZero(t, args.Info.EphemeralID)
 	assert.NotZero(t, args.Info.FirstStart)
@@ -100,6 +101,7 @@ func TestRunnerParams(t *testing.T) {
 	err := args.Config.Unpack(&m)
 	require.NoError(t, err)
 	assert.Equal(t, map[string]interface{}{
+		"name": "my-custom-name",
 		"output": map[string]interface{}{
 			"console": map[string]interface{}{
 				"enabled": true,

internal/beatcmd/config.go

@@ -35,6 +35,10 @@ type Config struct {
 	// APMServer holds apm-server.* configuration.
 	APMServer *config.C `config:"apm-server"`
 
+	// Allow overwriting beat.Info.Name. This is mainly for stack monitoring
+	// and reporting purposes.
+	Name string `config:"name"`
+
 	MaxProcs  int `config:"max_procs"`
 	GCPercent int `config:"gc_percent"`