now.json

{
  "env": {
    "FIREBASE_API_KEY": "@firebase_api_key",
    "FIREBASE_AUTH_DOMAIN": "@firebase_auth_domain",
    "FIREBASE_PROJECT_ID": "@firebase_project_id",
    "FIREBASE_CLIENT_EMAIL": "@firebase_client_email",
    "FIREBASE_PRIVATE_KEY": "@firebase_private_key",

    "FORMSPREE_CONTACT_ID": "@formspree_contact_id",

    "AWS_ACCESS_KEY_ID": "@aws_access_key_id",
    "AWS_SECRET_ACCESS_KEY": "@aws_secret_access_key",
    "AWS_SES_CONTACT_EMAIL": "@aws_ses_contact_email",

    "GOOGLE_ANALYTICS_TRACKING_ID": "@google_analytics_tracking_id"
  },
  "build": {
    "env": {
      "REACT_APP_FIREBASE_API_KEY": "@firebase_api_key",
      "REACT_APP_FIREBASE_AUTH_DOMAIN": "@firebase_auth_domain",
      "REACT_APP_FIREBASE_PROJECT_ID": "@firebase_project_id",

      "REACT_APP_FORMSPREE_CONTACT_ID": "@formspree_contact_id",

      "REACT_APP_GOOGLE_ANALYTICS_TRACKING_ID": "@google_analytics_tracking_id"
    }
  }
}