check pod is ready

ready.sh

#!/bin/sh

# Initial delay in seconds
DELAY=1
# Maximum number of retries
MAX_RETRIES=5

# Automatically set Pod name and namespace
POD_NAME=$HOSTNAME
NAMESPACE=$(cat /var/run/secrets/kubernetes.io/serviceaccount/namespace)

# Kubernetes API endpoint to check pod status
API_ENDPOINT="https://kubernetes.default.svc.cluster.local/api/v1/namespaces/$NAMESPACE/pods/$POD_NAME"

retry_count=0
while [ $retry_count -lt $MAX_RETRIES ]; do
    # Use wget to call the Kubernetes API
    readiness=$(wget -O - --header="Authorization: Bearer $(cat /var/run/secrets/kubernetes.io/serviceaccount/token)" --no-check-certificate "$API_ENDPOINT" 2>/dev/null | grep -o '"ready":[true,false]*' | cut -d':' -f2)

    if [ "$readiness" = "true" ]; then
        # Pod is ready, exit with 0
        exit 0
    else
        # Pod is not ready, wait for the exponential backoff delay
        echo "Pod is not ready. Retrying in $DELAY seconds..."
        sleep $DELAY
        # Double the delay for the next iteration
        DELAY=$((DELAY * 2))
        retry_count=$((retry_count + 1))
    fi
done

# If we've reached here, all retries have failed
echo "Pod readiness check failed after $MAX_RETRIES retries."
exit 1

In this version, I've replaced the awk commands with grep and cut, which should be more compatible with BusyBox's limited toolset.