I have been developing a web application using Python, Flask, Docker(-Compose) and git/github and getting to the point where I try to figure out the best way/workflow to bring it to production. I have read some articles but not sure what is a best practice from different approaches.

My current setup is purely development oriented:

• Local Docker using docker-compose to build various service images (such as db, backend workers, webapp (flask & uwisg), nginx).
• using .env file for docker-compose to pass configuration to the services
• Source code is bind mounted from the local docker host
• db data is stored in a named volume
• Using local git for source control (though I have connected it to a github repository but not been using it much since I am the only one currently developing the application)

From what I understand the steps to production could be the following:

• Implement docker-compose override to distinguish between dev and prod
• Implement Dockerfile Multistage builds to create prod images which include the source code in the image and do not include dev dependencies
• Tag and push the production images to a registry (docker, google?) or better push the git to github?
• [do security scans of the prod images]
• deploy/pull the prod images from the registry (or build from github) on a service like GKE for instance

Is this a common way to do it? Am I missing something?

How would I best go about using an integration/staging environment between dev and prod, so that I can first test new prod builds or debug prod images in integration?

Does GKE for instance offer an easy way to setup an integration environment? Or could I use the Docker installation on my NAS for that?

Any best practices for backing up production (like db data most importantly)?

Thanks in advance!