Kubernetes configmap in json format error

Question

I am trying to mount a file probes.json to an image. I started with trying to create a configmap similar to my probes.json file by manually specifying the values.

However, when I apply the replicator controller, I am getting an error.

How should I pass my JSON file to my configmap / how can I specify my values in data parameter?

I tried the below steps, however, I got an error.

$ cat probes.json 
[
  {
    "id": "F",
    "url": "http://frontend.stars:80/status"
  },
  {
    "id": "B",
    "url": "http://backend.stars:6379/status"
  },
  {
    "id": "C",
    "url": "http://client.stars:9000/status"
  }
]

Configmap:

apiVersion: v1
kind: ConfigMap
metadata:
  name: my-vol-config
  namespace: stars
data:
  id: F
  id: B
  id: C
  F: |
   url: http://frontend.stars:80/status
  B: |
   url: http://backend.stars:6379/status
  C: |
   url: http://client.stars:9000/status

ReplicaContainer:

apiVersion: v1
kind: ReplicationController
metadata:
  name: management-ui
  namespace: stars
spec:
  replicas: 1
  template:
    metadata:
      labels:
        role: management-ui
    spec:
      containers:
      - name: management-ui
        image: calico/star-collect:v0.1.0
        imagePullPolicy: Always
        ports:
        - containerPort: 9001
        volumeMounts:
          name: config-volume
        - mountPath: /star/probes.json
      volumes:
        - name: config-volume
          configMap:
             name: my-vol-config

Error:

kubectl apply -f calico-namespace/management-ui.yaml
service "management-ui" unchanged
error: error converting YAML to JSON: yaml: line 20: did not find expected key

I think the lastest yaml is not valid. Check with yamllint.com for example. I think you will need to remove the dashes before the keys and it will do — Tomas Dowling
– Tomas Dowling, Commented Oct 3, 2018 at 3:24

stacksonstacks · Accepted Answer · 2018-10-03 03:44:03Z

6

This part, - should be with name: on first line under volumeMounts

    volumeMounts:
      name: config-volume
    - mountPath: /star/probes.json

Like so:

    volumeMounts:
      - name: config-volume
        mountPath: /star/probes.json

answered Oct 3, 2018 at 3:44

stacksonstacks

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user_01_02 · Accepted Answer · 2018-10-03 19:46:40Z

I wanted to add more points that i have learned today,

Mounting a file using the below code will delete any files under the directory in this case star directory in the container.

-    volumeMounts:
      - name: config-volume
        mountPath: /star/probes.json

to solve it we should use subpath

  volumeMounts:
    - name: "config-volume"
      mountPath: "/star/probes.json"
      subPath: "probes.json"

Instead of fiddling on how to pass key-value pairs into the data , try passing as json file and remember to specify the namespace while creating the configmap

In my example: I have probes.json and i tried to pass it as such without passing each value to my data. I used the below command to create my configmap

kubectl create configmap config --namespace stars --from-file calico-namespace/probes.json

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