Elastic Agent: env provider fails with unhelpful log message %!s(<nil>) #9284
Description
Elastic Agent Version:
8.18.4 (running as Fleet-managed agent via Helm Chart)
Elastic Stack Version (Cloud):
8.18.4 (Elastic Cloud deployment)
Deployment Context:
Agent deployed via Helm (elastic-agent chart v8.18.4)
Mode: daemonset
All required ${env.*} variables are explicitly defined using extraEnvs in the Helm chart
Variables include:
NODE_NAME
NODE_IP
POD_NAME
KUBERNETES_SERVICE_HOST
KUBERNETES_SERVICE_PORT
etc.
Observed Behavior:
In the Elastic Agent logs, the following error message appears repeatedly every 30 seconds:
provider "env" failed to run (will retry in 30s): %!s()
Expected Behavior:
Either no error (if all required env values are present), or
A meaningful error message indicating which variable is missing or causing the failure
Actual Behavior:
The log contains a Go formatting fallback string %!s(), which strongly suggests that the error value passed to the logger is nil, and the Stringer is not handled correctly.
Code Reference:
The problematic log line seems to originate from controller.go line 471, inside the composable.providers.env provider controller:
logger.Errorf("provider %q failed to run (will retry in %s): %s", provider.Type(), retryDur, err)
If err is nil, this results in the log message:
provider "env" failed to run (will retry in 30s): %!s()
Root Cause Hypothesis:
err may be nil, and the retry mechanism is triggered regardless
Notes:
Agent behavior is otherwise functional — all Kubernetes metrics and logs are collected correctly and delivered to Elastic
This issue affects log clarity and may mislead users during debugging