Looking for Google Cloud Platform expert.

I have an existing Ruby on Rails app. The app is currently deployed on Heroku. We want to move to GCloud. All environmental vars are currently stored in Heroku config vars. We want to still maintain environmental variable simply in GCloud UI. Each environment should use unique variables for isolation. Currently we use a mix of external tools to power app Mailgun (SMTP) S3 (data storage -- only sitemap) Heroku auto SSL (using LetsEncypt) We want to bring the app and these external tools all into Google Cloud (hosted on app engine / or recommended alternative): Mail API (SMTP) Google Cloud Storage (sitemap , photo hosting #95 ) LetsEncypt auto cert gen The open-source app is hosted on Github repo and deploys using production and staging branches. Currently deploys to appropriate instances on Heroku (via commit).Both have unique environmental variables. We want to have same simple dev pipeline, but deploy to Google CP on commit Note, staging can publicly accessible for simplicity (but should set env var that uses [login to view URL] to prevent being indexed). Staging: [login to view URL] Production: https://explorer.trekview.org. Please contact me if you are expert.