How to parse .env file (dotenv) with Helm template?

Question

I'm migrating from Docker to Helm3. My Docker deployment uses .env files to load environment variables see reference. During the migration I need to support both the old way and new way so I don't want change the .env format if I can avoid it.

Here's my sample .env file:

key1=value1
key2=value2

Then in my Helm3 deployment.yaml I need:

kind: Deployment
spec:
  template:
    spec:
      containers:
          env:
            - name: key1
              value: "value1"
            - name: key2
              value: "value2"

The .env file is the helm project root directory so I'm hoping I can do something like this based on this question but not sure how to proceed:

  {{- $files := .Files }}
  #Not sure how to select just one file?
  {{- range tuple ".env" }}
  
      #Split file by newlines and =
      {{- range $line := splitList "\n" $files.Get . }}
        {{/* Break the line into words */}}
        {{- $kv := splitList "=" $line -}}
        {{- $k := first $kv -}}
        {{ $k }}: {{ last $kv | quote }}
      {{- end }}

  {{- end }}

You can't refer to `.Files` in the `templates` directory; you need to move the file somewhere else. [Accessing Files Inside Templates](https://helm.sh/docs/chart_template_guide/accessing_files/) in the Helm documentation has more information on `.Files`, including how to retrieve a specific file. — David Maze, Feb 17 '21 at 17:46

score 1 · Accepted Answer · answered Feb 18 '21 at 14:58

Here's what worked for me but I'm open to a better answer. The only things I don't understand is why I need the empty line {{""}} - I thought new lines would have been inserted without that.

The issue I had with the answer from @Matt was that the indentation came out wrong.

{{ $file := .Files.Get ".env" | trimSuffix "\n" }}
{{- range $line := splitList "\n" $file -}}
{{- $kv := splitList "=" $line -}}
    {{ "" }}
    - name: {{ first $kv }}
      value: {{ last $kv | quote }}
{{- end }}

score 0 · Answer 2 · answered Feb 18 '21 at 10:58

Here is what I have come up with.

kind: Deployment
spec:
  template:
    spec:
      containers:
        env:
{{ $files := .Files }}
{{- range tuple ".env" -}}
    {{- $file := $files.Get . | trimSuffix "\n" -}}
    {{- range $line := splitList "\n" $file -}}
      {{- $kv := splitList "=" $line -}}
      {{- $k := first $kv -}}
      {{- $v := last $kv -}}
      {{- printf "- name: \"%s\"\n" $k | indent 8 }}
      {{- printf "  value: \"%s\"\n" $v }}
    {{- end }}
{{- end }}

It should work copypasted assuming .env file is placed in helm project root directory

I tested it with following .env file:

key1=value1
key2=value2

And got the following yaml as the output:

---
kind: Deployment
spec:
  template:
    spec:
      containers:
        env:
        - name: "key1"
          value: "value1"
        - name: "key2"
          value: "value2"

How to parse .env file (dotenv) with Helm template?

2 Answers2