flow: only use component health when component implements component.H…

…ealthComponent (#3740)

* Revert "Default back to healthy when a component does not implement component.HealthComponent (#3558)"

This reverts commit b2f8992. The commit
introduced a bug where the "default health" message was always returned
for healthy components, overriding the message informing the user when
the last time the component evaluated was.

* flow: only use component health if component exposes health

This commit offers an alernative approach to #3558, where the overall
health of a component only considers the component implementation of
health if that component implements the component.HealthComponent
interface.

Without this commit, the zero value of component.Health was always
returned, considering the health of every component as being "unknown."

CHANGELOG.md

@@ -32,6 +32,11 @@ Main (unreleased)
 
 - Disable node_exporter on Windows systems (@jkroepke)
 
+### Bugfixes
+
+- Fix issue where component evaluation time was overridden by a "default
+  health" message. (@rfratto)
+
 ### Other changes
 
 - Add metrics when clustering mode is enabled. (@rfratto)

component/component_health.go

@@ -45,16 +45,6 @@ var (
 	_ encoding.TextUnmarshaler = (*HealthType)(nil)
 )
 
-// Default Health returns a copy of the default health for use when a component
-// does not implement HealthComponent.
-func DefaultHealth() Health {
-	return Health{
-		Health:     HealthTypeHealthy,
-		Message:    "default health",
-		UpdateTime: time.Now(),
-	}
-}
-
 const (
 	// HealthTypeUnknown is the initial health of components, set when they're
 	// first created.

pkg/flow/internal/controller/component.go

@@ -445,17 +445,14 @@ func (cn *ComponentNode) CurrentHealth() component.Health {
 	var (
 		runHealth  = cn.runHealth
 		evalHealth = cn.evalHealth
-
-		componentHealth component.Health
 	)
 
 	if hc, ok := cn.managed.(component.HealthComponent); ok {
-		componentHealth = hc.CurrentHealth()
-	} else {
-		componentHealth = component.DefaultHealth()
+		componentHealth := hc.CurrentHealth()
+		return component.LeastHealthy(runHealth, evalHealth, componentHealth)
 	}
 
-	return component.LeastHealthy(runHealth, evalHealth, componentHealth)
+	return component.LeastHealthy(runHealth, evalHealth)
 }
 
 // DebugInfo returns debugging information from the managed component (if any).