gistfile1.txt

...
spec:
  contatiners:
  - env:
    - name: REQUESTS_CA_BUNDLE 
      value: /opt/cert/bundle.pem
    volumeMounts:
    - mountPath: /opt/cert
      name: custom-cert
      subPath: cert
      readOnly: true
    ...
  volumes:
  - name: custom-cert
    secret:
      secretName: custom-cert
      items:
      - key: bundle.pem
        path: cert/bundle.pem
...