When running simple container images like Ubuntu or Alpine in Minikube, you might encounter the dreaded CrashLoopBackOff state accompanied by Error syncing pod messages. This occurs even with basic commands:

kubectl run ubuntu --image=ubuntu

The pod appears to start but immediately terminates with status Completed, triggering Kubernetes' restart policy which creates the loop.

Unlike server applications like Nginx that run as persistent processes, Ubuntu's base image executes /bin/bash as its default command and exits immediately when not running interactively. The container lifecycle looks like:

1. Container starts (State: Running)
2. Default command completes (State: Terminated, Exit Code: 0)
3. Kubernetes restarts container (State: Waiting, Reason: CrashLoopBackOff)
4. Cycle repeats

Here are three working approaches to keep your Ubuntu container running:

Method 1: Run an Infinite Loop

kubectl run ubuntu --image=ubuntu --command -- /bin/sh -c "while true; do sleep 10; done"

Method 2: Create a Deployment with Custom Command

apiVersion: apps/v1
kind: Deployment
metadata:
  name: ubuntu-deployment
spec:
  replicas: 1
  selector:
    matchLabels:
      app: ubuntu
  template:
    metadata:
      labels:
        app: ubuntu
    spec:
      containers:
      - name: ubuntu
        image: ubuntu
        command: ["/bin/bash"]
        args: ["-c", "tail -f /dev/null"]

Method 3: Attach Interactive Shell

For debugging purposes, you can force an interactive session:

kubectl run -i --tty ubuntu --image=ubuntu --restart=Never -- bash
# Remember to delete afterward:
kubectl delete pod ubuntu

When troubleshooting, always check:

• kubectl describe pod [pod-name] - Shows termination reason
• kubectl logs [pod-name] --previous - Views logs from crashed instance
• kubectl get events --sort-by=.metadata.creationTimestamp - Chronological event log

If problems persist in Minikube:

# Reset the cluster (warning: destructive)
minikube delete
minikube start

# Check resource allocation
minikube config set memory 4096
minikube config set cpus 2

Remember that base OS images aren't designed to run as services - they're meant as building blocks. For production, always use proper process managers or define appropriate commands in your Kubernetes manifests.

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When running basic container images like Ubuntu or Alpine in Minikube using commands like:

kubectl run ubuntu --image=ubuntu

The pod enters a CrashLoopBackOff state with these key indicators:

• Container status shows "Reason: Completed" with Exit Code 0
• Events log shows "Back-off restarting failed container"
• Frequent "Error syncing pod" messages

The fundamental issue stems from how Kubernetes treats containers differently than Docker. Unlike Docker which keeps containers running by default, Kubernetes expects containers to:

• Run a persistent process (like Nginx does)
• Explicitly declare a command to keep running
• Not exit immediately (which Ubuntu/Alpine do by default)

Method 1: Force the container to stay alive

kubectl run ubuntu --image=ubuntu --command -- sleep infinity

Method 2: Create a proper Deployment manifest

apiVersion: apps/v1
kind: Deployment
metadata:
  name: ubuntu-deployment
spec:
  replicas: 1
  selector:
    matchLabels:
      app: ubuntu
  template:
    metadata:
      labels:
        app: ubuntu
    spec:
      containers:
      - name: ubuntu
        image: ubuntu
        command: ["/bin/bash", "-c", "--"]
        args: ["while true; do sleep 30; done;"]

Nginx containers inherently run a persistent web server process, making them Kubernetes-friendly out of the box. Compare these behaviors:

# Nginx (works)
kubectl run nginx --image=nginx

# Ubuntu (requires adjustment)
kubectl run ubuntu --image=ubuntu --command -- tail -f /dev/null

When facing similar issues:

1. Check container logs:

   kubectl logs -p POD_NAME

2. Inspect events:

   kubectl get events --sort-by=.metadata.creationTimestamp

3. Test with interactive shell:

   kubectl run -i --tty debug --image=ubuntu --restart=Never -- bash

For Minikube environments:

• Verify VM resources: minikube ssh free -m
• Check Docker driver compatibility
• Consider newer Minikube versions (v0.24.1 is quite old)