Metrics fetches never timeout

[kcking]

Hello all.

We have found an issue in our cluster where the operator metric fetch loop can get stuck waiting for a DB Ping or Exec that will never time out. I believe this can be solved by using PingContext and ExecContext inside of clickhouse.go, and passing in a context.Context with a reasonable timeout -- maybe something like 10 seconds.

What do you folks think? Thanks for the awesome operator!

[sunsingerus]

Yes, sure we need to introduce some kind of timeout for SQL processor, which runs queries towards ClickHouse instances in Pods. So far this part (monitoring in general and SQL queries in particular) is done in simple and straightforward manner, mainly because there are plenty of other thing to look after, and in order to have monitoring "operational in general".

[filimonov]

@kcking sounds reasonable. can you prepare the PR with that change?

[kcking]

just added a PR!