A simple bash script that takes a .env file with key and value separated by "=". It base64 encodes the value and produces a key value pair separated by a colon

env-to-kubernetes-secret.bash

#!/bin/bash

input="env_file_path"
secret_name="my-secret_name"
rm ./deployment_env.yaml ./secret_pair.txt
while IFS='=' read -r key value
do
  if [[ ! -z "$key" && ! -z "$value" && "$key" != "#"* ]]
  then
    encoded=$(echo -n "$value" | base64 -w0)
    echo "$key: $encoded" >> secret_pair.txt
    var_block="
      - name: $key
        valueFrom:
          secretKeyRef:
            name: $secret_name
            key: $key"
    echo "$var_block">> deployment_env.yaml
  fi
done < "$input"

The format for the .env file should be:

KEY=value

New modification to the scripts allows you to define the env blocks for the deployments too.