recovery: optional restore_command & allow custom command if needed

Right now the role assumes you always want to use barman-wal-restore
script as a restore command to recover WAL files at startup time of a
standby server.

This PR adds a new `primary.restore_command` option which lets you
override the command to use.

⚠️ Breaking change: the PR renames the existing
`primary.restore_directory` option to
`primary.restore_barman_directory` ⚠️ in order to give more context to
this option which will automatically use the `barman-wal-restore`
script as a restore command.

Finally if none of the two options specified above are specified in
the `primary:` object then the `restore_command` is left commented out
in the PG configuration (which is totally fine as it will try to
recover WALs from the primary server directly see
[documentation](https://www.postgresql.org/docs/12/warm-standby.html#STANDBY-SERVER-OPERATION))

1 files changed, 5 insertions, 1 deletions

diff --git a/templates/recovery.conf.j2 b/templates/recovery.conf.j2
index 059b234..7078429 100644
--- a/templates/recovery.conf.j2
+++ b/templates/recovery.conf.j2
@@ -2,7 +2,11 @@
 # {{ ansible_managed }}
 
 standby_mode = 'on'
-restore_command = '/usr/bin/barman-wal-restore --user barman --parallel 8 {{ postgres_barman_server }} {{ postgres_primary.restore_directory }} %f %p'
+{% if postgres_primary.restore_command is defined %}
+restore_command = '{{ postgres_primary.restore_command }}'
+{% elif postgres_primary.restore_barman_directory is defined %}
+restore_command = '/usr/bin/barman-wal-restore --user barman --parallel 8 {{ postgres_barman_server }} {{ postgres_primary.restore_barman_directory }} %f %p'
+{% endif %}
 primary_conninfo = 'host={{ postgres_primary.host }} port={{ postgres_primary.port }} user={{ postgres_primary.replication_user }} password={{ postgres_primary.replication_password }} sslmode=require'
 trigger_file = '/var/lib/postgresql/{{ postgres_version }}/{{ postgres_cluster_name }}/failover.trigger'
 recovery_target_timeline='latest'