Output environment variables based on AWS SSM params and write .env files. This might be helpful when relying on centrally managed environments variables for local development or CICD

create-env.sh

#!/bin/bash

set -e
# Enable -x only for debug purposes
#set -x

# Retrieves a JSON parameter from SSM and output them as key/values
# ./create-env.sh -p <system manager param name>
# Write the output to .env.local
# ./create-env.sh -p <system manager param name> > .env.local
#
# Expects an existing Systems Manager Param with the following structure:
# {
#  key_1: property_1,
#  key_2: property_2,
#  key_3: property_3,
# } 




check_arg() {
  local argument_name=$1
  local argument=$2
  if [[ -z $argument ]]; then
    echo "Missing required argument: $argument_name" >&2
    usage
    exit 1
  fi
}

# Function to display script usage
usage() {
  echo "Basic Usage: $0 -p <system manager param name> "
  echo "Usage to persist an env file: $0 -p <system manager param name> > .env"
}

not_authenticated() {
  echo "Unable to access AWS services due to missing or timed out AWS credentials. Please re-login to AWS."
}

# Parse command line arguments
while getopts ":p:" opt; do
  case $opt in
    p)
      parameter_name=$OPTARG
      ;;
    \?)
      echo "Invalid option: -$OPTARG" >&2
      usage
      exit 1
      ;;
    :)
      echo "Option -$OPTARG requires an argument." >&2
      usage
      exit 1
      ;;
  esac
done

check_arg "SystemParam" $parameter_name

sts_string=$(aws sts get-caller-identity | jq -r '.Arn')
if [[ $sts_string == *"Unable to locate credentials"* ]]; then
  not_authenticated
  exit 1
fi

get_config_json() {
  local parameter_name=$1

  json=$(aws ssm get-parameter --name "$parameter_name" --with-decryption --query 'Parameter.Value' --output text)
  json=$(echo "$json" | tr -d "'")
  echo $json
}

parameters_json=$(get_config_json $parameter_name)

PROPERTY_1=$(echo $parameters_json | jq -r '.property_1')
PROPERTY_2=$(echo $parameters_json | jq -r '.property_2')
PROPERTY_3=$(echo $parameters_json | jq -r '.property_3')


ENV_FILE=$(cat <<EOF
KEY_1=$PROPERTY_1
KEY_2=$PROPERTY_2
KEY_3=$PROPERTY_3
EOF)

# Use this to write .env from within this script
# echo "$ENV_FILE" | sed 's/\\n/\n/g' > .env
echo "$ENV_FILE" | sed 's/\\n/\n/g'