metrics and profiling not working after upgrade to 14.0.5

[shiresn]

not sure if this is related to upgrade , after upgrade to 14.0.5 admin area\Settings\Metrics and profiling stop working,

in production log

Started GET "/admin/application_settings/metrics_and_profiling" for 10.32.232.12 at 2021-07-17 01:03:34 +0000
Processing by Admin::ApplicationSettingsController#metrics_and_profiling as HTML
  Rendered layout layouts/admin.html.haml (Duration: 160.4ms | Allocations: 23320)
Completed 500 Internal Server Error in 182ms (ActiveRecord: 2.1ms | Elasticsearch: 0.0ms | Allocations: 31654)

ActionView::Template::Error (undefined local variable or method `prometheus_multiproc_dir' for #<ActionView::Base:0x00000000252128>
Did you mean?  prometheus_default_multiproc_dir):
    15:         - unless Gitlab::Metrics.metrics_folder_present?
    16:           .form-text.text-muted
    17:             %strong.cred= _("WARNING:")
    18:             = _("Environment variable %{code_start}%{environment_variable}%{code_end} does not exist or is not pointing to a valid directo
ry.").html_safe % { environment_variable: prometheus_multiproc_dir, code_start: '<code>'.html_safe, code_end: '</code>'.html_safe }
    19:             = link_to sprite_icon('question-o'), help_page_path('administration/monitoring/prometheus/gitlab_metrics', anchor: 'metrics-sh
ared-directory')
    20:     .form-group
    21:       = f.label :metrics_method_call_threshold, _('Method Call Threshold (ms)'), class: 'label-bold

after check gitlab doc here i add below env in docker run parameter ,it worked but i'm not sure if this suitable to be default value in env?
prometheus_multiproc_dir=/dev/shm

[paolomainardi]

Same problem here (and others), i'll try this fix.

[sue445]

I confirmed this problem at v13.12.4 too.

[paolomainardi]

Just to follow up on this, the fix works as expected

[paulknulst]

I encountered that error too. I can also confirm that the fix works!

[hohomin320]

In synology DS920+ DSM 7.0 environment When I applied the above solution,
the 500 error problem on the Metrics and profiling page was resolved.
thank you