postgresql: Decouple wal_g from streaming replication.

Streaming replication may be used even if `wal-g` is not -- as long as
the user can move a copy of the base backup to the replica (e.g. using
`pg_basebackup`).  Remove the warning about this combination, and move
the `primary_conninfo` setting outside of the `s3_backups_bucket`
check.

puppet/zulip/manifests/profile/postgresql.pp

@@ -55,13 +55,6 @@ class zulip::profile::postgresql {
   }
 
   if $replication_primary != undef and $replication_user != undef {
-    if $s3_backups_bucket == '' {
-      $message = @(EOT/L)
-          Replication is enabled, but s3_backups_bucket is not set in zulip-secrets.conf!  \
-          Streaming replication requires wal-g backups be configured.
-          |-EOT
-      warning($message)
-    }
     # The presence of a standby.signal file triggers replication
     file { "${zulip::postgresql_base::postgresql_datadir}/standby.signal":
       ensure  => file,

puppet/zulip/templates/postgresql/12/postgresql.conf.template.erb

@@ -788,17 +788,18 @@ listen_addresses = <%= @listen_addresses %>
 <% end -%>
 
 <% if @s3_backups_bucket != '' -%>
-# Streaming backups and replication
+# WAL backups to S3 (may also be used for replication)
 archive_mode = on
 archive_command = '/usr/bin/timeout 10m /usr/local/bin/env-wal-g wal-push %p'
 restore_command = '/usr/local/bin/env-wal-g wal-fetch "%f" "%p"'
+<% end -%>
 <% unless @replication_primary.nil? || @replication_user.nil? -%>
+# Streaming replication
 primary_conninfo = 'host=<%= @replication_primary %> user=<%= @replication_user -%>
 <% if @replication_password != '' %> password=<%= @replication_password %><% end -%>
 <% unless @ssl_mode.nil? %> sslmode=<%= @ssl_mode %><% end -%>
 '
 <% end -%>
-<% end -%>
 
 <% unless @ssl_cert_file.nil? -%>
 ssl_cert_file = '<%= @ssl_cert_file %>'		# (change requires restart)

puppet/zulip/templates/postgresql/13/postgresql.conf.template.erb

@@ -819,17 +819,18 @@ listen_addresses = <%= @listen_addresses %>
 <% end -%>
 
 <% if @s3_backups_bucket != '' -%>
-# Streaming backups and replication
+# WAL backups to S3 (may also be used for replication)
 archive_mode = on
 archive_command = '/usr/bin/timeout 10m /usr/local/bin/env-wal-g wal-push %p'
 restore_command = '/usr/local/bin/env-wal-g wal-fetch "%f" "%p"'
+<% end -%>
 <% unless @replication_primary.nil? || @replication_user.nil? -%>
+# Streaming replication
 primary_conninfo = 'host=<%= @replication_primary %> user=<%= @replication_user -%>
 <% if @replication_password != '' %> password=<%= @replication_password %><% end -%>
 <% unless @ssl_mode.nil? %> sslmode=<%= @ssl_mode %><% end -%>
 '
 <% end -%>
-<% end -%>
 
 <% unless @ssl_cert_file.nil? -%>
 ssl_cert_file = '<%= @ssl_cert_file %>'		# (change requires restart)

puppet/zulip/templates/postgresql/14/postgresql.conf.template.erb

@@ -840,17 +840,18 @@ listen_addresses = <%= @listen_addresses %>
 <% end -%>
 
 <% if @s3_backups_bucket != '' -%>
-# Streaming backups and replication
+# WAL backups to S3 (may also be used for replication)
 archive_mode = on
 archive_command = '/usr/bin/timeout 10m /usr/local/bin/env-wal-g wal-push %p'
 restore_command = '/usr/local/bin/env-wal-g wal-fetch "%f" "%p"'
+<% end -%>
 <% unless @replication_primary.nil? || @replication_user.nil? -%>
+# Streaming replication
 primary_conninfo = 'host=<%= @replication_primary %> user=<%= @replication_user -%>
 <% if @replication_password != '' %> password=<%= @replication_password %><% end -%>
 <% unless @ssl_mode.nil? %> sslmode=<%= @ssl_mode %><% end -%>
 '
 <% end -%>
-<% end -%>
 
 <% unless @ssl_cert_file.nil? -%>
 ssl_cert_file = '<%= @ssl_cert_file %>'		# (change requires restart)

puppet/zulip/templates/postgresql/zulip.conf.template.erb

@@ -40,17 +40,18 @@ effective_io_concurrency = <%= @effective_io_concurrency %>
 <% end -%>
 
 <% if @s3_backups_bucket != '' -%>
-# Streaming backups and replication
+# WAL backups to S3 (may also be used for replication)
 archive_mode = on
 archive_command = '/usr/bin/timeout 10m /usr/local/bin/env-wal-g wal-push %p'
 restore_command = '/usr/local/bin/env-wal-g wal-fetch "%f" "%p"'
+<% end -%>
 <% unless @replication_primary.nil? || @replication_user.nil? -%>
+# Streaming replication
 primary_conninfo = 'host=<%= @replication_primary %> user=<%= @replication_user -%>
 <% if @replication_password != '' %> password=<%= @replication_password %><% end -%>
 <% unless @ssl_mode.nil? %> sslmode=<%= @ssl_mode %><% end -%>
 '
 <% end -%>
-<% end -%>
 
 <% unless @ssl_cert_file.nil? -%>
 ssl_cert_file = '<%= @ssl_cert_file %>'		# (change requires restart)