With upgrade to Alpine 3.13, support for `hash:` and `btree:` has
beenremoved from Alpine.
As such `hash:<file>` references do not work any more.
[Alpine](https://wiki.alpinelinux.org/wiki/Release_Notes_for_Alpine_3.13.0)
explains it like this:
> Oracle has changed the license of BDB to AGPL-3.0, making it unsuitable
> to link to packages with GPL-incompatible licenses. Since the old version
> is no longer maintained, the db package is now deprecated. Alpine Linux
> packages are being transitioned to alternatives or, where no alternatives
> exist, removed entirely.
This, unfortunately, will mean that the new version of `docker-postfix`
might not be backwards-compatible, if you're using your own postfix
configuration. Sorry. :-(
- It's now possible to choose the logging type - either 'plain' or
'json'
- The code is ready to support multiple integration tests (with
different configurations)
- `OPENDKIM_` and `POSTFIX_` variables are handled properly and recorded
in the corresponding files. (This had a downfall that `bash` now needs
to be installed, so we can probably simplify some of the shell
scripts.)
