I would like to pass in some of the values in kubernetes yaml files during runtime like reading from config/properties file. 

what is the best way to do that?

In the below example, I do not want to hardcode the port value, instead read the port number from config file.

Ex:

```
logstash.yaml

```

---

```
apiVersion: v1
kind: ReplicationController
metadata:
name: test
namespace: test
spec:
replicas: 1
selector:
app: test
template:
metadata:
  labels:
    app: test
spec:
  containers:
  - name: test
    image: logstash
    ports:
    - containerPort: 33044 (looking to read this port from config file)
    env:
    - name: INPUT_PORT
      value: "5044"

config.yaml

logstash_port: 33044

```