Support fault tolerance and load balance with vert.x pool of reactive mysql client

[benstonezhang]

Add support to config load balance url for reactive mysql datasources in application.properties, for example

quarkus.datasource.reactive.url=mysql:loadbalance://192.168.32.101:3306,192.168.32.102:3306/dbname

or more simple

quarkus.datasource.reactive.url=mysql://192.168.32.101:3306,192.168.32.102:3306/dbname

[Sanne]

LGTM in principle, but I've never used this capability; better to rely on review from others about it being suitable.

Wouldn't it need some documentation changes?

It certainly needs to be squashed.

[benstonezhang]

@Sanne I expect no document change needed. The PR just try to mimic load balance url supported by MySQL Connector/J driver. With this patch, we can use similar url for reactive datasource of mysql too.
You can refer to issue #31492 for more information.

[cescoffier]

PArodn my ignorance, but it's fault tolerance, right? Is fatal tolerance a thing in MySQL?

[benstonezhang]

@cescoffier Here the fault tolerance is about connection to mysql. With vert.x pool of mysql client, we can create connections to the servers in pool. In case of one server down and cause an active connection is broke, we still can use other alive connections in pool.

[cescoffier]

We need @tsegismont review - he is the expert.

[tsegismont]

I'll review it today.

[tsegismont]

Thank you @benstonezhang

I think it is a good idea to support connection load-balancing.

Nevertheless, instead of parsing the url, I would prefer we change its type in DataSourceReactiveRuntimeConfig:

quarkus/extensions/reactive-datasource/runtime/src/main/java/io/quarkus/reactive/datasource/runtime/DataSourceReactiveRuntimeConfig.java

Line 29 in 96605e8

public Optional<String> url = Optional.empty();

Instead of a Optional<String> field, we could have Optional<List<String>>.

Existing configurations wouldn't be broken, and users could configure it with either several values comma-separated, or Indexed Properties.

[benstonezhang]

That's great. It would be more clear.

[benstonezhang]

@tsegismont The change of DataSourceReactiveRuntimeConfig would have bigger impact. What's the action I can take by now?

[tsegismont]

Right, the change would be relatively bigger. On the other hand, it would be more maintainable on the long term. If you're willing to update the PR, I will review it.

[benstonezhang]

OK. I will work on it and update the PR.

[benstonezhang]

@tsegismont I create a new PR #31994 name as "Support config reactive datasource with list of database urls for fault tolerance and load balance". Please review.

[benstonezhang]

PR move to #31994. Close this one.