How to copy a local file into a helm deployment

Question

I'm trying to deploy in Kubernetes several pods using a mongo image with a initialization script in them. I'm using helm for the deployment. Since I'm beginning with the official Mongo docker image, I'm trying to add a script at /docker-entrypoint-initdb.d so it will be executed right at the beginning to initialize some parameters of my Mongo.

What I don't know is how can I insert my script, that is, let's say, in my local machine, in /docker-entrypoint-initdb.d using helm.

I'm trying to do something like docker run -v hostfile:mongofile but I need the equivalent in helm, so this will be done in all the pods of the deployment

Answer 1

You can use configmap. Lets put nginx configuration file to container via configmap. We have directory name called nginx with same level values.yml. Inside there we have actual configuration file.

apiVersion: v1
kind: ConfigMap
metadata:
  name: nginx-config-file
  labels:
    app: ...    
data:
  nginx.conf: |-
{{ .Files.Get "nginx/nginx.conf" | indent 4 }}

---

apiVersion: apps/v1beta2
kind: Deployment
metadata:
  name: SomeDeployment
  ...  
spec:
  replicas: 
  selector:
    matchLabels:
      app: ...
      release: ...
  template:
    metadata:
      labels:
        app: ...
        release: ...
    spec:
      volumes:
        - name: nginx-conf
          configMap:
            name: nginx-config-file
            items:
            - key: nginx.conf
              path: nginx.conf
      containers:        
        - name: ...
          image: ...          
          volumeMounts:
            - name: nginx-conf
              mountPath: /etc/nginx/nginx.conf
              subPath: nginx.conf

You can also check initContainers concept from this link : https://kubernetes.io/docs/concepts/workloads/pods/init-containers/