adding metric for total login attempts

[xinau]

Motivation

issue: #92

this change adds a metric keycloak_login_attempts for the total number of login attempts. it might seem that it's possible to sum both keycloak_logins and keycloak_failed_login_attempts but as the totalLogins and totalFailedLoginAttempts are counted separately their is now guarantee that both counters contain the same metrics (labels with same values). in order to make it possible to calculate the failure rate per instance a new counter totalLoginAttempts is introduced.

Checklist:

• [x] Code has been tested locally by PR requester
• [ ] Changes have been successfully verified by another team member

Progress

• [x] Finished task

Screenshot

[pb82]

@xinau Why not use a selector that ignores the labels (or some of them) to build the sum?

[xinau]

@pb82 the problem with ignoring labels is that it's still not helpful as shown in the folliwng screenshot. the problem still remains. without filtering all labels their can still be a margin of error >40%.

[pb82]

this looks good @xinau Sorry for the delay, will add this to the next release

[xinau]

@pb82 thanks. :)

[pb82]

thanks @xinau