Unable to use FF_USE_DUMB_INIT_WITH_KUBERNETES_EXECUTOR

I'm attempting to use the FF_USE_DUMB_INIT_WITH_KUBERNETES_EXECUTOR flag in order to send SIGTERM to my job scripts in runner Pods on an OpenShift cluster.

The FF_USE_DUMB_INIT_WITH_KUBERNETES_EXECUTOR flag is mentioned in these closed issues as a way to propagate SIGTERM:

• gitlab-org/gitlab-runner!4443 (merged)
• gitlab-org/gitlab-runner!4485 (merged)

When setting this flag, my job Pods fail to start because the default helper image does not contain the dumb-init command.

 cp: cannot stat '/usr/bin/dumb-init': No such file or directory

Is there another helper image I should be using? gitlab-org/charts/gitlab-runner!385 (merged) looks possibly related, but the tini command is also not present in the helper image.