Is there a universal interface I can use?

[Tilman Baumann]

On 28.11.2017 00:38, Stuart Bishop wrote:
> On 23 November 2017 at 21:37, Tilman Baumann
> <tilman.baumann at canonical.com> wrote:
>> I didn't want to talk about it before it's usable. I think I might be
>> working on something similar.
>>
>> https://github.com/tbaumann/jujucharm-layer-cassandra-backup
>>
>> It seems to only use "nodetool snapshot"
>> I'm integrating this for a 3rd party so I don't quite know what is going
>> on there. But looks like the intent is pretty much the same.
> 
> I think this charm needs to remain a subordinate, because 'nodetool
> snapshot' requires a JMX connection and that should be blocked
> (because it is not secured).
> 
> I'd be happy to have actions on the main Cassandra charm to manage
> snapshots, and cronned snapshots would also be a feature suitable for
> the main charm. But you would still need some way to ship the
> snapshots to your backup host which should be a subordinate.


That would be quite nice actually. Backup and snapshot could be two
different actions even.
Snapshot is a little low-level as it is per-node. But it makes for fast
recovery if a node hickups.
Full backup like Haw Leoeung implemented in
https://jujucharms.com/u/hloeung/cassandra-backup/ is probably even more
useful for many scenarios.

I'm quite stumped right now with the odd combination of needing to be a
subordinate and needing to connect to the database relation.
I just can't get it to work. And I'm out of ideas.
I would love to just finish it "to get it to work" but I don't know what
else I could try at this point.

Generally I like the idea of just plonking on subordinates to extend
features.
But backup is a quite central one. Makes sense in the main charm.

The percona charm has for example a backup action too. I just checked.
It also just places a file in the file-system.
(No cron scheduled one. But that would be useful there too)

Very nice would be a unified backup plugin thing that lives in
charmhelpers and could interact with some backup server. Wishful
thinking... :D
Might eve be a nice use of the not yet supported shared storage thing
https://jujucharms.com/docs/stable/charms-storage


I'm not very familiar with the coding style used in the cassandra charm.
But I think I could help you with adding those functionalities even.
I will have a lot of distractions the next two weeks. But I can see what
I can do...


Thanks
 Tilman