Kubernetes deployment from inside a running pod

create-deployment.py

# see https://github.com/kubernetes-client/python/blob/master/examples/deployment_create.py

from os import path

import yaml

from kubernetes import client, config


def main():
  # Configs can be set in Configuration class directly or using helper
  # utility. If no argument provided, the config will be loaded from
  # default location.
  config.load_incluster_config()

  with open(path.join(path.dirname(__file__), "nginx-deployment.yaml")) as f:
    dep = yaml.safe_load(f)
    k8s_apps_v1 = client.AppsV1Api()
    resp = k8s_apps_v1.create_namespaced_deployment(
        body=dep, namespace="default")
    print("Deployment created. status='%s'" % resp.metadata.name)

if __name__ == '__main__':
    main()

create.sh

#/bin/bash

#
# run this script to build the container, run the pod and observe the deployment
#
# observe pod creation with:
#   watch -n 2 -d kubectl get pods
#

# uncomment these lines to create a minikube environment
#minikube start
#eval $(minikube docker-env)

# build the container
docker build \
  -t testdep \
  .
  
# apply the rbac so the pod has permission
kubectl apply -f rbac.yaml

# run a single container
kubectl run \
  -it \
  --rm \
  spawner \
  --image=testdep \
  --restart=Never \
  --image-pull-policy=Never

# show the status
kubectl get pods,deployments

# update
sleep 10
kubectl get pods,deployments

# cleanup
kubectl delete deployment/nginx-deployment
sleep 10

# check the cleanup
kubectl get pods,deployments

Dockerfile

from python:3-slim

run pip install kubernetes

copy create-deployment.py /src/
copy nginx-deployment.yaml /src/

workdir /src

cmd python create-deployment.py

nginx-deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80

rbac.yaml

kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: deployment-create
rules:
- apiGroups: ["apps"]
  resources: ["deployments"]
  verbs: ["create"]
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: pods-list
subjects:
- kind: ServiceAccount
  name: default
  namespace: default
roleRef:
  kind: ClusterRole
  name: deployment-create
  apiGroup: rbac.authorization.k8s.io