Split into scoped commits with messages if further details are needed, view those via the associated PR :)
**Commit Summary:**
**`check-for-changes.sh`**
- Prevent `SSL_DOMAIN` silently skipping when value has wildcard prefix `*.` (_at least this was known as a bugfix when originally committed in linked PR_).
- Improved inlined docs for maintainers.
- Additional logging for debugging.
**`helper-functions.sh:_extract_certs_from_acme`**:
- Fail if the input arg (_`$CERT_DOMAIN`, aka the FQDN_) provided for extraction is empty.
- Use `$CERT_DOMAIN` in place of `$HOSTNAME` and `$1` for a consistent value (_previously could mismatch, eg with `SSL_DOMAIN` defined_).
- The conditional is now only for handling extraction failure (_key or cert value is missing from extraction_).
- Log an actual warning or success (debug) based on outcome.
- Don't use `SSL_DOMAIN` with wildcard value for the `mkdir` letsencrypt directory name (_wildcard prefix `*.` is first stripped instead_).
**`acme_extract`** (_new python utility for `acme.json` handling_):
- Extracted out into a python script that can be treated as a utility in the `$PATH` like other helper scripts. It can now be used and optionally tested directly instead of via `helper-functions.sh`.
-Made compatible with Python 3, as Python 2 is EOL and no longer in newer versions of Debian.
