Fix TLS cert generation

[katefike]

Background

• TLS certs are being generated within the sage-mailserver container's entrypoint.sh.

Problem

• The code block to generate the TLS certs in entrypoint.sh is hitting an error (see logs below)
  • -> the script exits
  • -> the container restarts
  • -> the code block re-executed and re-errors
• You can't get exec into the container when it's in the restart loop - every restart kicks your out of the container session.

  sage-mailserver  | Generating TLS certs...
  ...
  sage-mailserver  | /entrypoint.sh: line 12: CRITICAL ERROR: Failed to find TLS cert files.: command not found
  sage-mailserver exited with code 0

• Another problem is that when the container restarts, it runs the certbot command to generate TLS certs again. Letsencrypt rate-limits the cert request attempts. Unfortunately I ran entrypoint.sh 5x and am prohibited from requesting certs from Letsencrypt for 2 days :(

Solution

• Create a cron job that generates the TLS certs and renews them:
  • Create and remove a container for running the certbot command.
  • Store the certs in a docker volume.
  • Load the certs into the sage-mailserver container
• Source: https://coderevolve.com/certbot-in-docker/

Completed in this pull request: https://github.com/katefike/sage/pull/104