I want to create a file based on the value of a key from a ConfigMap. I'm following the ConfigMap guide on how to setup a volume that is populated from a ConfigMap but it doesn't seem to be working.

Here is my ConfigMap:

apiVersion: v1
data:
  redis-config: |
    maxmemory 2mb
    maxmemory-policy allkeys-lru
kind: ConfigMap
metadata:
  name: example-redis-config

And my pod:

apiVersion: v1
kind: Pod
metadata:
  name: redis
spec:
  containers:
  - name: redis
    image: kubernetes/redis:v1
    env:
    - name: MASTER
      value: "true"
    ports:
    - containerPort: 6379
    resources:
      limits:
        cpu: "0.1"
    volumeMounts:
    - mountPath: /redis-master-data
      name: data
    - mountPath: /redis-master
      name: config
  volumes:
    - name: data
      emptyDir: {}
    - name: config
      configMap:
        name: example-redis-config
        items:
        - key: redis-config
          path: redis.conf

Both of those are just copied from the guide. I've then created both via kubectl. However, the redis container fails to start. Checking the logs gives the following error:

$ kubectl logs redis
[7] 24 May 22:22:53.146 # Fatal error, can't open config file '/redis-master/redis.conf'

What am I doing wrong?