barman-wal-archive / put-wal using (custom) compression

[thoro]

Hi,

I started using put-wal / barman-wal-archive and checkout out compression (https://www.endpoint.com/blog/2017/03/28/postgres-wal-files-best-compression)

barman-wal-archive is currently not able to use any compression (via any parameter at least) and I thought for everyone using wal-archive via a internet connection this might actually be very helpful.

I envision something like in the config file, where you can put either a supported algorithm i.e. gzip or you can give the path to a custom script that executes the compression algorithm.

for example:

barman-wal-archive --compression=custom --custom_compression_filter=compress_wal.sh barman pg

The compression option should also take existing compression options: bzip2, gzip, pybzip2, pygzip, pigz