Parsing a single tfvars file into lambda resource and nodejs app

README.md

I dislike having multiple copies of the same env file, for example when trying to run some integration tests I needed to access the same env variables that I had to load into a lambda resource in terraform.

to make this easier I place the app related env variables in a tfvars file and loop and load them into the lambda env variables like so:

locals {
  node-env     = "test"
  app_env_vars = { 
    for line in split("\n", file("app.tfvars")):
      trimspace(split("=", line)[0]) => trimspace(split("=", line)[1])
      if strcontains(line, "=")
  }
}

esource "aws_lambda_function" "test_lambda" {

  ......

  environment {
    variables = tomap(merge(
    {
      LOG_LEVEL               = 20
      ENV                     = local.node-env
      NODE_ENV                = local.node-env
    },
    local.app_env_vars
  ))
  }
}

and on the app side or in the npm scripts, I need to trim the tfvars from any spaces and load them into the bash env:

export $(cat infra/app.tfvars | tr -d '[:blank:]')

or you could load them up as part of app startup:

export const isProduction = () => {
  return process.env.NODE_ENV === "production";
};

export function loadEnv(): Record<string, string> {
  return isProduction() ? process.env : parseVarsFile("infra/app.tfvars");
}

function parseVarsFile(fileLocation: string): Record<string, string> {
  const vars = {};
  readFileSync(fileLocation, "utf-8")
    .split(/\r?\n/)
    .forEach(function (line) {
      if (!/\S/.test(line)) return; //skip if line is empty
      const parts = line.split("=");
      const key = parts[0].trim();
      if (key.startsWith("//") || key.startsWith("#")) return; // skip if line is commented
      const value = parts[1]
        .replace(/( |\t)+\#.*/g, "") // replace any comments or spaces after the value
        .replace(/( |\t)+\/{2}.*/g, "") // replace any comments or spaces after the value
        .trim(); // replace all spaces before and after final value
      vars[key] = value;
    });
  return vars;
}

example tfvars:

LOG_LEVEL        = 20 # log debug - change to 30 info to reduce noise once stable
YUM_USERNAME_KEY = order_status_lambda/yum_api_username
YUM_PASSWORD_KEY = order_status_lambda/yum_api_password
SECRETS_CACHE_DURATION_SECS = 900
APP_AWS_REGION=eu-central-1
STUB=false // used for integration tests in CI and locally to bypass stubbing of external services