Update process

Initial conditions:

• Raspberry Pi with current docker image A (DI_A),
• The new update as docker image B (DI_B).
• Theoretical instances on the Raspberry Pi 1 and 2 (DC_1, DC_2).
• The Nginx with the hostname equal to the container name of DC_1 and therefore DC_1 used for the active service
• DC_1 running with DI_A

Github pipeline:

1. Github: Change on trunk
2. Github: Build and Test
3. Github: Execute docker build
4. Github: Push docker image to the image registry
5. Github: Call all deployment projects in parallel

For each deployment project:

1. Github: Connect to the Raspberry Pi via SSH
2. RBP: Download DI_B, read current hostname from Nginx config
3. RBP: Start DC_2 with current hostname as an argument and DI_B and remember container name
4. DC_2: Call DC_1 using the delivered hostname and sync the current state
5. RBP: Wait for full startup of DC_2, save DC_2 docker container name as the new hostname in the Nginx config
6. RBP: Reload Nginx
7. RBP: Remove DC_1 container

The next time this gets repeated with DC_1 and DC_2 switched.