mysql ha lock session expires after session wait_timeout

[ffkaka]

HA with MySQL physical backend
With the MySQL backend, I can see frequent active node changing at every session wait_timeout. So the active node changing period is depending on the configuration of mysql.

(wait_timeout=300sec for test, every cross line means active node switching)

but I want to make less active node switching because every active node switching will cause a bad response for some vault requests in our service. Honestly, I don't expect the active node to change unless the active node gets in trouble.

Currently, the session which has been used to acquire the mysql lock will not be used again until it loses the lock. So I think we can use this session for monitoring lock instead of which is doing it using a random session. Therefor the lock session won't get to the wait_timeout and lose lock.

[hsimon-hashicorp]

Can you please provide more information about your configuration? Thanks!

[ffkaka]

Hi this is my configuration for the mysql backend. Thanks.

storage "mysql" {
        address = "a.b.com:3306"
        username = "user"
        password = "password"
        database = "database"
        table = "vault"
        tls_ca_file = "/crtpath/chainca.crt"
        ha_enabled = "true"
        lock_table = "vault_lock"
}

[ffkaka]

#18749

hi @hsimon-hashicorp
I made a simple solution for this issue. Could you please have a review of this PR