How to override Go environment variables with Helm-CodePudding

How do I override environment variables in a .env file for Go with Helm?

With C# I do the following:

In appsettings.json:

{
    "Animals":{
        "Pig": "Squeek"
    },
}

In values.yaml:

animals:
  pig: "Oink"

In configmap.yaml:

apiVersion: v1
kind: ConfigMap
metadata:
  name: animal-configmap
pig: {{ .Values.animals.pig }}

And finally in deployment.yaml:

spec:
  ...
  template:
    ...
    spec:
      ...
      containers:
          ...
          env:
            - name: Animals__Pig
              valueFrom:
                configMapKeyRef:
                  name: animal-configmap  
                  key: pig

Not the double __. How would one go about updating an environment value for Go?

Here is the Go .env file example:

PIG=SQUEEK

CodePudding user response：

If your Go code is retrieving an ordinary environment variable

pig := os.Getenv("PIG")

then the Kubernetes manifest should use that name as the environment variable name:

env:
  - name: PIG
    valueFrom: {...}

The double-underscore doesn't have any special meaning in Unix environment variables or the Kubernetes manifest, in your initial example it looks like the way the C# framework separates components when it maps environment variables to application properties. If you're using environment variables directly you don't need to do anything special.

CodePudding user response：

You can use the "github.com/joho/godotenv" package to read .env files. Since you don't want to mix up existing environment variables with those from the .env file, you can create a map and set the vars to it.

If you have a .env file like this:

HELLO=word

You can read it like this:

package main

import (
    "fmt"
    "log"

    "github.com/joho/godotenv"
)

func main() {
    var envs map[string]string
    envs, err := godotenv.Read(".env")

    if err != nil {
        panic("Error loading .env file")
    }

    name := envs["HELLO"]

    fmt.Println(name)
}

If you set a var env, you can still access the value defined on the file:

$ HELLO=ping go run main.go

world

Then you access the file vars from the envs var.