depl.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: some-deployment
  labels:
    app: some-app
spec:
  replicas: 1
  selector:
    matchLabels:
      app: some-app
  template:
    metadata:
      labels:
        app: some-app
    spec:
      initContainers:
      - name: setup-app
        image: debian:stretch-slim
        command: 
          - bash
          - '-c'
          - |
            # false  # uncomment to simulate failure
            set -euo pipefail
            for i in {1..5}; do
              echo "Setup doing its setuppy things"
              sleep 1
            done

      containers:
      - name: some-app
        image: debian:stretch-slim
        command: 
          - bash
          - '-c'
          - |
            set -euo pipefail
            while true; do
              echo "App doing its appy things"
              sleep 1
            done