To help in developing features, the Dockerfile and its entrypoint have been extended.
The README.md explains stuff in detail, in short:
- you can now run a Patroni cluster with a single command
Due to the renaming of Governor to Patroni some old references needed to be updated.
Also some python packages need to be added.
Added entrypoint.sh as a script, to ensure Patroni will have PID = 1 when the container is run.
Implement callback actions for patroni in order to call external script on different events in the server lifecycle, supported are on start, stop, restart, reload and role change (which covers both promote and demote). A callback should receive 3 arguments: action, role and cluster name (in this order), and can do things like tagging the EC2 instances associated with PostgreSQL, or notifying the DBA when the master had been demoted.
A sample callback that assigns tags to AWS instances is provided.
For 'on_stop' or 'on_restart' callbacks we cannot
call is_leader, because the cluster would be stopped.
Instead, call is_leader before running a callback.
In addition, make the call_nowait more robust by handling
the exceptions related to the DB cluster unavailability.
Functionality provided by that module will be achieved via callbacks.
- fix a typo in aws.py
- fix some mixups of old code and new callbacks in postgresql.py
List of ZooKeeper nodes could be periodically updated from Exhibitor
Since we know that each Exhibitor accompanies one ZooKeeper node, list
of Exhibitor nodes also maintained. Exhibitor assumes that all ZooKeeper
nodes are using the same client port, 2181. The same assumption is valid
for Exhibitor, it should always listen on the same port on all nodes.
Original list of Exhibitor nodes is cached and used as a fallback when
it failed ito query information with using maintained list.
This implementation is using the same interface (AbstractDCS) as Etcd
class. It means that there should be no problem to implement another
plugin to work agains Consul for example.
Feike Steenbergen