Cascading Replication

First, the good news.  Setting up a chain of replicas has now become fairly simple even for non-DBAs.  Here's the basic steps:

1. Edit pg_hba.conf to enable replication connections.
2. Edit postgresql.conf to turn on the various replication options.
3. Restart the master.
4. Set up passwordless access to the master from the first replica.
5. Use pg_basebackup to snapshot the master from the replica.
6. Create a recovery.conf pointing at the master.
7. Start the replica.
8. Run pg_basebackup on the second replica.
9. Edit recovery.conf to point at the first replica.
10. Start the second replica.
11. Repeat steps 8-10 for as many replicas you want to chain.