x-pack/filebeat/input/httpjson: propagate request trace configuration…

… to chain children

This ensures that all chain child clients will log request traces with the same details
as the top level request trace logger.

CHANGELOG.next.asciidoc

@@ -168,6 +168,7 @@ Setting environmental variable ELASTIC_NETINFO:false in Elastic Agent pod will d
 - Add support for complete URL replacement in HTTPJSON chain steps. {pull}37486[37486]
 - Add support for user-defined query selection in EntraID entity analytics provider. {pull}37653[37653]
 - Update CEL extensions library to v1.8.0 to provide runtime error location reporting. {issue}37304[37304] {pull}37718[37718]
+- Add request trace logging for chained API requests. {issue}37551[36551] {pull}37682[37682]
 
 *Auditbeat*
 

x-pack/filebeat/input/httpjson/input.go

@@ -122,6 +122,16 @@ func run(ctx v2.Context, cfg config, pub inputcursor.Publisher, crsr *inputcurso
 	if cfg.Request.Tracer != nil {
 		id := sanitizeFileName(ctx.ID)
 		cfg.Request.Tracer.Filename = strings.ReplaceAll(cfg.Request.Tracer.Filename, "*", id)
+
+		// Propagate tracer behaviour to all chain children.
+		for i, c := range cfg.Chain {
+			if c.Step != nil { // Request is validated as required.
+				cfg.Chain[i].Step.Request.Tracer = cfg.Request.Tracer
+			}
+			if c.While != nil { // Request is validated as required.
+				cfg.Chain[i].While.Request.Tracer = cfg.Request.Tracer
+			}
+		}
 	}
 
 	metrics := newInputMetrics(reg)