Sidecar container is starting before main containers
Production Risk
Low — normal startup state; only a concern if it persists beyond expected startup time.
A sidecar container (defined as an initContainer with restartPolicy: Always) is in the SidecarContainerStarting state. This is a normal transitional state in the Kubernetes 1.28+ SidecarContainers feature where sidecars are started before main containers and stopped after them.
- 1Pod uses the SidecarContainers feature gate (enabled by default in 1.29+).
- 2An initContainer is defined with restartPolicy: Always, making it a sidecar.
- 3The sidecar container image is being pulled or the container process is initializing.
Pod is starting up and a sidecar container has not yet reported Ready.
kubectl describe pod my-pod # Init Containers: # my-sidecar: # State: Waiting # Reason: SidecarContainerStarting
expected output
State: Waiting Reason: SidecarContainerStarting
Fix 1
Wait for the sidecar to become ready
WHEN Pod is in normal startup sequence
kubectl get pod my-pod -w
Why this works
SidecarContainerStarting is transient; once the sidecar passes its startup/readiness probe it transitions to Running.
Fix 2
Check sidecar container logs if startup is prolonged
WHEN Sidecar remains in SidecarContainerStarting for more than expected
kubectl logs my-pod -c my-sidecar kubectl describe pod my-pod | grep -A 15 "my-sidecar:"
Why this works
Logs reveal application errors; describe shows probe configuration and recent events.
✕
SidecarContainers feature gate introduced as alpha.
SidecarContainers promoted to beta and enabled by default.
Kubernetes 1.28 — Sidecar Containers
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