JS to read AWS SSM variables for use in Gitlab CI process

.env.development

#This is used locally by Create-React-App during development

#Cognito Region
REACT_APP_REGION=us-east-1

REACT_APP_USER_POOL_ID=us-east-1_youruserpoolid
REACT_APP_APP_CLIENT_ID=yourcognitoappclientidgoeshere

.gitignore

# Ignore our Gitlab CI generated SSM file
.env.ssm

.gitlab-ci.yml

#Reusable script definition
.build-script:
  script: &build_script
    - yarn install --frozen-lockfile
    - echo "Loading AWS SSM Variables into .env.ssm file"
    - export AWS_PROFILE=${CI_ENVIRONMENT_NAME}
    - echo AWS_PROFILE is ${AWS_PROFILE}
    - node ./read-ssm.js
    - echo "Building files..."
    - env $(cat .env.ssm | xargs) yarn build
    - echo "Build successful!"
  artifacts: &build_artifacts
    name: "$CI_JOB_NAME-$CI_COMMIT_REF_NAME"
    paths:
      - build/

#Build for development on every push
build-dev:
  stage: build
  only:
    - branches
  except:
    - master
    - develop
  environment:
    name: development
  script: *build_script
  artifacts: *build_artifacts

config.js

/**
 * process.env items are configured in .env files or environment variables
 *   and can be overriden at build time
 * see https://facebook.github.io/create-react-app/docs/adding-custom-environment-variables
 */

/** AWS config */
export const REGION = process.env.REACT_APP_REGION;
export const USER_POOL_ID = process.env.REACT_APP_USER_POOL_ID;
export const APP_CLIENT_ID = process.env.REACT_APP_APP_CLIENT_ID;

read-ssm.js

const fs = require('fs');
const AWS = require('aws-sdk');

/**
 * Used by the build process to inject AWS SSM params into environment variables
 *
 * NOTE: To run this locally you may need to either set AWS_REGION env var
 * or use the value in your ~/.aws/config file by:
 * AWS_SDK_LOAD_CONFIG=true node ./read-ssm.js
 */

/**
 * All of these keys will be looked up in SSM and their values added to the build environment
 */
const SSM_NAMES = {
  '/cognito/sample/pool/id': 'REACT_APP_USER_POOL_ID',
  '/cognito/sample/client/web/id': 'REACT_APP_APP_CLIENT_ID'
};

const writeEnvFile = keyVals => {
  fs.writeFileSync('./.env.ssm', keyVals.join('\n'));
};

const retrieveParams = async () => {
  const ssm = new AWS.SSM();
  const params = await ssm
    .getParameters({
      Names: Object.keys(SSM_NAMES)
    })
    .promise();

  const keyVals = params.Parameters.map(p => `${SSM_NAMES[p.Name]}=${p.Value}`);

  //Grab the region from the AWS_REGION or AWS_SDK_LOAD_CONFIG setting
  keyVals.push(`REACT_APP_REGION=${AWS.config.region}`);

  console.log(keyVals);

  writeEnvFile(keyVals);
};

retrieveParams();