This worked on # Now I am testing #

# sudo -u postgres pgbackrest --stanza=my_cluster --log-level-console=info stanza-create
2020-11-13 16:45:42.674 P00 INFO: stanza-create command begin 2.30: --log-level-console=info --pg1-host=pg-master --pg1-host-user=postgres --pg1-path=/var/lib/pgsql/13/data --repo1-path=/var/lib/pgbackrest --stanza=my_cluster
WARN: unable to check pg-1: [UnknownError] remote-0 process on 'pg-master' terminated unexpectedly [255]: Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).
ERROR: [056]: unable to find primary cluster - cannot proceed
2020-11-13 16:45:42.809 P00 INFO: stanza-create command end: aborted with exception [056]