k8s pod readiness http API

test-http-readiness-api.yaml

---
apiVersion: v1
kind: ConfigMap
metadata:
  name: test-readiness-balthazar-readiness-pod-script
  namespace: datadog
data:
  readiness-pod.py: |
    #!/usr/bin/env python3

    import os

    from http.server import BaseHTTPRequestHandler, HTTPServer


    class ReadinessCheck(BaseHTTPRequestHandler):

        def is_ready(self):
            ready = os.path.exists('/ready')
            if ready:
                print("Ready!")
            else:
                print("Not ready..")
            return ready

        def do_GET(self):
            if self.is_ready():
                self.send_response(200)
            else:
                self.send_response(400)
            self.end_headers()
            self.wfile.write(b'')

    def main():
        HTTPServer(('', 8080), ReadinessCheck).serve_forever()

    if __name__ == '__main__':
        main()


---

apiVersion: apps/v1
kind: Deployment
metadata:
  name: test-readiness-balthazar
  namespace: datadog
spec:
  replicas: 1
  selector:
    matchLabels:
      app: test-readiness-balthazar
  template:
    metadata:
      labels:
        app: test-readiness-balthazar
    spec:
      serviceAccountName: cassandra
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
              - matchExpressions:
                - key: node-role.kubernetes.io/cassandra-contexts
                  operator: Exists
      tolerations:
      - key: node
        operator: Exists
        effect: NoSchedule
      volumes:
      - name: readiness-pod-script
        configMap:
          name: test-readiness-balthazar-readiness-pod-script
          defaultMode: 0755
      containers:
      - name: main-pod
        image: cassandra-toolbox:3.11
        imagePullPolicy: IfNotPresent
        resources:
          limits:
            cpu: 100m
            memory: 128Mi
          requests:
            cpu: 100m
            memory: 128Mi
        command:
        - /bin/bash
        - -c
        - "sleep infinity"
      - name: readiness-pod
        image: cassandra-toolbox:3.11
        imagePullPolicy: IfNotPresent
        volumeMounts:
        - name: readiness-pod-script
          mountPath: /tmp
        resources:
          limits:
            cpu: 100m
            memory: 64Mi
          requests:
            cpu: 100m
            memory: 64Mi
        readinessProbe:
          httpGet:
            path: /
            port: 8080
          initialDelaySeconds: 3
          periodSeconds: 3
        command:
        - /tmp/readiness-pod.py