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.
In case if one member of a cluster is not available it will retry with
another one and fetch the new cluster configuration. Default timeout for
all requests to etcd is 5 seconds.
Initial cluster configuration can be resolved through:
1) /v2/members call on one of the cluster members on a client port
2) when it is possible to resolve hostname into multiple ip's it will
iterate through list and try to perform action from 1)
3) If there is discovery_srv defined in etcd section of config file it
will resolve peer addresses of all cluster members and will fetch
cluster configuration with using peer protocol by doing /members call on
a peer port
connect_address give possibility to specify listen address and connect
address separetely, so there is no need to determine your external
address by doing requests to amazon api.
For example you can listen on 0.0.0.0 but provide service on some
didicated ip. This should cover all possible use-cases when you are
running behind firewall, load balancer or inside for example docker.
Create a superuser role with a given name and password (or change
the postgres role if the name is not given). Also, create an admin
role with the name and the password provided. The admin role has
CREATEDB and CREATEROLE permisssions, effectively making it the
most powerful role after the superuser.
When PostgreSQL is running inside the docker container, it should provide
the address of the host it's running on and not the address from inside
of the container to the outside world.
