* debian/design.md: Add section on DCS availability and current status

debian/design.md

@@ -210,6 +210,18 @@ ExecStart=/usr/bin/patroni /etc/patroni/%i.yml
 This makes it possible to e.g. start Patroni for the '10/main' instance with
 `systemctl start patroni@10/main`.
 
+DCS Debian availability
+-----------------------
+
+The only DCS server available in Debian 9 (stretch) is zookeeper. Both etcd and
+consul were blacklisted before release by the Debian security team due to being
+written in Go.
+
+Current testing (buster) also includes etcd and consul.
+
+The latest Patroni Debian package is available for both Debian stable and
+testing/unstable via the PGDG APT repository.
+
 DCS setup
 ---------
 
@@ -230,3 +242,18 @@ The `patronictl` CLI currently looks for a configuration file
 configuration under `/etc/patroni/`. In the pg-common scope, it could
 addtionally either display all pg-common instances and/or accept the '%v/%c'
 instance notation in order to select a specific instance to display or act on.
+
+Current status
+--------------
+
+As of the postgresql-common_194 and patroni_1.5.0-9 packages, the following
+steps are still needed for each pg-common instance %v/%c:
+
+ 1. Setup DCS and possibly install its client python packages
+ 2. Install postgresql-common package
+ 3. Disable automatic instance creation in
+    /etc/postgresql-common/createcluster.conf
+ 4. Install postgresql-%v package
+ 5. Setup authentication via pgpass or otherwise
+ 6. Create a /etc/patroni/%v-%c.yml configuration file
+ 7. Start the patroni systemd service for the instance