x-pack/filebeat/input/httpjson: allow empty cursor template values to be ignored by health status updates (#45361) (#45398)

Health status changes are evaluated in CI for integrations and in some
cases (aws.guardduty is the provocation here), there is a failed/empty
evaluation. So allow ignore_empty_value configurations for cursor
entries to also be ignored for health status updates, instead of being
noted as a health degradation.

(cherry picked from commit 0257f0c)

Co-authored-by: Dan Kortschak <dan.kortschak@elastic.co>

Author: mergify[bot]

CHANGELOG.next.asciidoc

@@ -474,6 +474,7 @@ otherwise no tag is added. {issue}42208[42208] {pull}42403[42403]
 - Add support for relationship expansion to EntraID entity analytics provider. {issue}43324[43324] {pull}44761[44761]
 - Update CEL mito extensions to v1.21.0. {issue}40762[40762] {pull}45107[45107]
 - Update CEL mito extensions to v1.22.0. {pull}45245[45245]
+- Allow empty HTTPJSON cursor template value evaluations to be ignored by Fleet health status updates. {pull}45361[45361]
 
 *Auditbeat*
 

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

@@ -53,14 +53,25 @@ func (c *cursor) update(trCtx *transformContext) {
 	}
 
 	for k, cfg := range c.cfg {
-		v, _ := cfg.Value.Execute(trCtx, transformable{}, k, cfg.Default, c.status, c.log)
+		stat := c.status
+		if cfg.mustIgnoreEmptyValue() {
+			stat = ignoreEmptyValueReporter{stat}
+		}
+		v, _ := cfg.Value.Execute(trCtx, transformable{}, k, cfg.Default, stat, c.log)
 		if v != "" || !cfg.mustIgnoreEmptyValue() {
 			_, _ = c.state.Put(k, v)
 			c.log.Debugf("cursor.%s stored with %s", k, v)
 		}
 	}
 }
 
+// ignoreEmptyValueReporter is an abuse of the type system to allow the cursor
+// update mechanism to signal to valueTpl.Execute not to report empty values
+// as health degraded.
+type ignoreEmptyValueReporter struct {
+	status.StatusReporter
+}
+
 func (c *cursor) clone() mapstr.M {
 	if c == nil || c.state == nil {
 		return mapstr.M{}

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

@@ -111,7 +111,9 @@ func (t *valueTpl) Execute(trCtx *transformContext, tr transformable, targetName
 			val, err = fallback(errExecutingTemplate)
 		}
 		if err != nil {
-			stat.UpdateStatus(status.Degraded, fmt.Sprintf("failed to execute template %s: %v", targetName, err))
+			if _, ignoreEmpty := stat.(ignoreEmptyValueReporter); !ignoreEmpty || !errors.Is(err, errEmptyTemplateResult) {
+				stat.UpdateStatus(status.Degraded, fmt.Sprintf("failed to execute template %s: %v", targetName, err))
+			}
 			log.Debugw("template execution failed", "target", targetName, "error", err)
 		}
 		tryDebugTemplateValue(targetName, val, log)