swarm example: suggested improvements

[warmanton]

I have stolon installed using https://github.com/sorintlab/stolon/tree/master/examples/swarm .
All worked fine util today I got etcd with "alarm:NOSPACE" withdefault 2Gb limit. Postgres service stopped working until I fixed quota overlimit. Does stolon need revision history entries from etcd ? How mutch is enough ? 100 ?

What would you like to be added:
- --auto-compaction-mode=revision
- --auto-compaction-retention=100
command line parameters for etcd (or any reasonable values) in https://github.com/sorintlab/stolon/blob/master/examples/swarm/docker-compose-etcd.yml

Also need some explanation about ${ETCD_TOKEN} and where it comes from (.env ?)

Please fix passwords for replica and postgres in swarm/docker-compose-pg.yml . Current example works only due to both passwords (replication and postgres users) are "password1" and "password1". If passwords are different then provided example does not work.

Why is this needed:
To get working from the box example for swarm

[sgotti]

@warmanton

The swarm example was contributed so you should ask to the original author (see the commit history). Feel free to open a PR to improve it.

Does stolon need revision history entries from etcd ? How mutch is enough ? 100 ?

This is documented here: https://github.com/sorintlab/stolon/blob/master/doc/architecture.md#etcdv3-compaction

Please fix passwords for replica and postgres in swarm/docker-compose-pg.yml . Current example works only due to both passwords (replication and postgres users) are "password1" and "password1". If passwords are different then provided example does not work.

Please open another issue or better a PR to fix this.

[warmanton]

#774