SSM utils for fetching and caching parameters

ssm.js

import { SSM } from "aws-sdk";
import ms from "ms";

const ssm = new SSM();
const SSM_PATH = process.env.SSM_PATH;
let cache = { params: {} };

const getParametersByPath = async (path) =>
  ssm
    .getParametersByPath({
      Path: path,
      Recursive: true,
    })
    .promise();

const loadParameters = async (cacheDuration = "1h") => {
  if (!isCacheEmpty() && !hasCacheExpired()) {
    // cache is valid. Do not reload.
    return;
  }

  console.log("Reloading SSM param cache...");
  if (SSM_PATH === null || SSM_PATH.length === 0) {
    throw new Error(
      "SSM_PATH is null. Please provide it via environment variables"
    );
  }
  const response = await getParametersByPath(SSM_PATH);
  const params = response.Parameters.reduce(
    (result, param) => ({
      ...result,
      [param.Name.substring(SSM_PATH.length + 1)]: param.Value,
    }),
    {}
  );

  //Update cache with new data and expiry
  cache = { params, expiredAt: new Date(Date.now() + ms(cacheDuration)) };
};

function isCacheEmpty() {
  return Object.keys(cache.params).length === 0;
}

function hasCacheExpired() {
  return !cache.expiredAt || new Date() > cache.expiredAt;
}

export const getParameters = async () => {
  await loadParameters();
  return cache.params;
};

export const getRootSSMPath = (scope) => {
  if (scope && scope.name && scope.stage) {
    return `/${scope.stage}/${scope.name}`;
  } else {
    return null;
  }
};

export const createSSMPath = (scope, key) => {
  if (scope && scope.name && scope.stage) {
    return `${getRootSSMPath(scope)}/${key}`;
  } else {
    return null;
  }
};

export const SSM_KEYS = {
  USER_POOL_ID: "USER_POOL_ID",
  USER_POOL_CLIENT_ID: "USER_POOL_CLIENT_ID",
  MEETINGS_TABLE: "MEETINGS_TABLE",
  USERS_TABLE: "USERS_TABLE",
};