[Jenkins] Temporary suspension of anonymous access to jenkins.impala.io

[Laszlo Gaal <la...@cloudera.com>]

Dear Impala contributors,

I regret to inform the community that the upstream Jenkins service is
currently experiencing multiple waves of sustained DDoS attacks, which are
interfering with normal operations.

As a mitigation measure, I have temporarily disabled anonymous access to
Jenkins. This should reduce the load on the service to a level that allows
pre-commit services to continue unimpeded. The suspension is intended to be
temporary until the Jenkins maintainers figure out a more sophisticated way
to protect the Jenkins instance from these attacks.

Unfortunately this also prevents non-committers from using the
gerrit-verify-dryrun-external convenience job. Committer access is
unchanged, but it is now mandatory to log int to Jenkins before being able
to use the service. Non-committer contributors are kindly asked to reach
out to committers (e.g. on this list, or on the Gerrit reviews) to run
gerrit-verify dryrun or gerrit-verify-dryrun-external on their behalf.

Please note that the Impala Gerrit review service is not impacted; patch
submission and review operations continue unchanged.
Further changes and developments will be communicated on this list as soon
as they happen.

Thank you for your support,

  - LaszloG