Learn Kubernetes Basics

Tasks

Kubernetes v1.16 documentation is no longer actively maintained. The version you are currently viewing is a static snapshot. For up-to-date documentation, see the latest version.

Edit This Page

Debug Init Containers

This page shows how to investigate problems related to the execution of Init Containers. The example command lines below refer to the Pod as <pod-name> and the Init Containers as <init-container-1> and <init-container-2>.

Before you begin

You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using Minikube, or you can use one of these Kubernetes playgrounds:

To check the version, enter kubectl version.

Checking the status of Init Containers

Display the status of your pod:

kubectl get pod <pod-name>

For example, a status of Init:1/2 indicates that one of two Init Containers has completed successfully:

NAME         READY     STATUS     RESTARTS   AGE
<pod-name>   0/1       Init:1/2   0          7s

See Understanding Pod status for more examples of status values and their meanings.

Getting details about Init Containers

View more detailed information about Init Container execution:

kubectl describe pod <pod-name>

For example, a Pod with two Init Containers might show the following:

Init Containers:
  <init-container-1>:
    Container ID:    ...
    ...
    State:           Terminated
      Reason:        Completed
      Exit Code:     0
      Started:       ...
      Finished:      ...
    Ready:           True
    Restart Count:   0
    ...
  <init-container-2>:
    Container ID:    ...
    ...
    State:           Waiting
      Reason:        CrashLoopBackOff
    Last State:      Terminated
      Reason:        Error
      Exit Code:     1
      Started:       ...
      Finished:      ...
    Ready:           False
    Restart Count:   3
    ...

You can also access the Init Container statuses programmatically by reading the status.initContainerStatuses field on the Pod Spec:

kubectl get pod nginx --template '{{.status.initContainerStatuses}}'

This command will return the same information as above in raw JSON.

Accessing logs from Init Containers

Pass the Init Container name along with the Pod name to access its logs.

kubectl logs <pod-name> -c <init-container-2>

Init Containers that run a shell script print commands as they’re executed. For example, you can do this in Bash by running set -x at the beginning of the script.

Understanding Pod status

A Pod status beginning with Init: summarizes the status of Init Container execution. The table below describes some example status values that you might see while debugging Init Containers.

Status Meaning
Init:N/M The Pod has M Init Containers, and N have completed so far.
Init:Error An Init Container has failed to execute.
Init:CrashLoopBackOff An Init Container has failed repeatedly.
Pending The Pod has not yet begun executing Init Containers.
PodInitializing or Running The Pod has already finished executing Init Containers.

Feedback