# How to Attach Large Files to a Pod using Helm and Kubernetes

A method for mounting files into a pod involves [adding ConfigMap data to a volume](https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-configmap/#populate-a-volume-with-data-stored-in-a-configmap), as shown below:

```yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: myconfigmap
data:
  myfile.txt: |
    this is the content of the file
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mydeployment
spec:
  replicas: 1
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      volumes:
      - name: myvolume
        configMap:
          name: myconfigmap
      containers:
        - name: mycontainer
          image: myimage
          volumeMounts:
          - name: myvolume
            mountPath: /mypath/myfile.txt
            subPath: myfile.txt
```

However, what if the file is large or challenging to maintain within the configMap definition? Wouldn't it be great if we could embed the content of a file into the configMap definition? Fortunately, this is possible if we use [Helm](https://blog.raulnq.com/useful-commands-for-helm) as a package manager for Kubernetes. Let's take the deployment of our own [Technology Radar](https://github.com/thoughtworks/build-your-own-radar?tab=readme-ov-file) in our Kubernetes cluster as an example.

## Pre-requisites

* Install [**Docker Desktop**](https://docs.docker.com/desktop/install/windows-install/)
    
* Enable [**Kubernetes**](https://docs.docker.com/desktop/kubernetes/) (the standalone version included in Docker Desktop)
    
* Install the [**Helm CLI**](https://helm.sh/docs/intro/install/).
    

## Helm Chart

Run the following command to create a Helm chart:

```powershell
helm create tech-radar
```

Create a `config.csv` file with the following [content](https://raw.githubusercontent.com/thoughtworks/build-your-own-radar/master/spec/end_to_end_tests/resources/sheet.csv). Navigate to the `tech-radar` folder; open the `values.yaml` file, and modify it as follows:

```yaml
replicaCount: 1
image:
  repository: wwwthoughtworks/build-your-own-radar
  pullPolicy: IfNotPresent
  tag: "latest"
nameOverride: ""
fullnameOverride: ""
```

Navigate to the `templates` folder and create a `configmap.yaml` file containing the following content:

```yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ include "tech-radar.fullname" . }}
  labels:
    {{- include "tech-radar.labels" . | nindent 4 }}
data:
  config.csv: |
{{ .Values.configCsv | indent 4 }}
```

Modify the `deployment.yaml` as follows:

```yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "tech-radar.fullname" . }}
  labels:
    {{- include "tech-radar.labels" . | nindent 4 }}
spec:
  replicas: {{ .Values.replicaCount }}
  selector:
    matchLabels:
      {{- include "tech-radar.selectorLabels" . | nindent 6 }}
  template:
    metadata:
      labels:
        {{- include "tech-radar.selectorLabels" . | nindent 8 }}
    spec:
      volumes:
      - name: config-volume
        configMap:
          name: {{ include "tech-radar.fullname" . }}  
      containers:
        - name: {{ .Chart.Name }}
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag | default .Chart.AppVersion }}"
          imagePullPolicy: {{ .Values.image.pullPolicy }}
          volumeMounts:
          - name: config-volume
            mountPath: /opt/build-your-own-radar/files/config.csv
            subPath: config.csv
          env:
            - name: SERVER_NAMES
              value: localhost 127.0.0.1
          ports:
            - name: http
              containerPort: 80
              protocol: TCP
          resources:
           limits:
             cpu: 2000m
             memory: 1024Mi
           requests:
             cpu: 2000m
             memory: 1024Mi
```

Remove the remaining `yaml` files.

## Release

Run the following command to install our chart:

```powershell
helm upgrade tech-radar-release tech-radar --install --set-file configCsv="./config.csv"
```

We can use `--set-file` to set the content of a file as a value for our chart. Run `kubectl describe configMap tech-radar-release` to see our configMap definition.

## The Application

Let's use port forwarding to test our application with the following command:

```powershell
kubectl port-forward deployment/tech-radar-release 8080:80
```

Navigate to [http://localhost:8080/](http://localhost:8080/) to see the application up and running. In another tab, navigate to the address [http://localhost:8080/files/config.csv](http://localhost:8080/files/config.csv), use the file in the application, and enjoy your own Technology Radar:

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1703292860399/9144f8c7-6ef0-49c0-9abb-60cbfeee6d48.png align="center")

The final scripts can be found [here](https://github.com/raulnq/k8s-helm-files)**.** Thank you, and happy coding.