What are some best practices you following in regards to using containers in production?

Images:

• Use images from official repositories
• Include only the packages you are going to use. Nothing else.
• Specify a tag in FROM instruction. Not using a tag means you'll always pull the latest, which changes over time and might result in unexpected result.
• Do not use environment variables to share secrets
• Keep images small! - you want them only to include what is required for the application to run successfully. Nothing else. Components:
• Secured connection between components (e.g. client and server)