"WARNING: Environment variable prometheus_multiproc_dir does not exist or is not pointing to a valid directory." out of the box

Summary

We run Gitlab CE on Kubernetes in GCP (image: gitlab/gitlab-ce:10.0.3-ce.0). Out of the box I see the following warning in admin UI:

WARNING: Environment variable prometheus_multiproc_dir does not exist or is not pointing to a valid directory.

Probably because of that /-/metrics gives me 404. I tried to setup the value for the environment variable manually and restart the pod:

~/pro/gitlab-ci-kubernetes (master *$=) → kubectl exec  gitlab-1205450473-4zmwv -n gitlab -- env | grep 'prometheus_multiproc_dir'
Defaulting container name to gitlab.
Use 'kubectl describe pod/gitlab-1205450473-4zmwv' to see all of the containers in this pod.
prometheus_multiproc_dir=/tmp/prometheus_multiproc_dir

but it didn't help. Probably because the directory does not exist:

~/pro/gitlab-ci-kubernetes (master *$=) → kubectl exec  gitlab-1205450473-4zmwv -n gitlab -- env | ls /tmp/prometheus_multiproc_dir
ls: /tmp/prometheus_multiproc_dir: No such file or directory
Defaulting container name to gitlab.
Use 'kubectl describe pod/gitlab-1205450473-4zmwv' to see all of the containers in this pod.

I couldn't find any official recommendation about the way the value should be setup so that would be great to have. But more importantly I believe the variable should be populated with a valid value out of the box.

Output of checks

Results of GitLab environment info

Expand for output related to GitLab environment info 
System information
System:
Current User:	git
Using RVM:	no
Ruby Version:	2.3.5p376
Gem Version:	2.6.13
Bundler Version:1.13.7
Rake Version:	12.0.0
Redis Version:	3.2.5
Git Version:	2.13.5
Sidekiq Version:5.0.4
Go Version:	unknown

GitLab information
Version:	10.0.3
Revision:	8895150
Directory:	/opt/gitlab/embedded/service/gitlab-rails
DB Adapter:	postgresql
URL:		https://gitlab.bol.io
HTTP Clone URL:	https://gitlab.bol.io/some-group/some-project.git
SSH Clone URL:	git@gitlab.bol.io:some-group/some-project.git
Using LDAP:	no
Using Omniauth:	no


GitLab Shell
Version:	5.9.0
Repository storage paths:
  • default: /gitlab-data/git-data/repositories Hooks: /opt/gitlab/embedded/service/gitlab-shell/hooks Git: /opt/gitlab/embedded/bin/git

Results of GitLab application Check

Expand for output related to the GitLab application check 
Checking GitLab Shell ...

GitLab Shell version >= 5.9.0 ? ... OK (5.9.0)
Repo base directory exists?
default... yes
Repo storage directories are symlinks?
default... no
Repo paths owned by git:root, or git:git?
default... yes
Repo paths access is drwxrws---?
default... yes
hooks directories in repos are links: ...
9/2 ... ok
8/5 ... ok
12/9 ... ok
16/10 ... ok
19/43 ... ok
20/44 ... repository is empty
17/48 ... ok
17/49 ... ok
17/50 ... ok
17/51 ... ok
17/52 ... ok
17/53 ... ok
17/54 ... ok
17/55 ... ok
17/56 ... ok
17/57 ... ok
17/58 ... ok
17/59 ... ok
17/60 ... ok
17/61 ... ok
17/62 ... ok
17/63 ... ok
17/64 ... ok
17/65 ... ok
17/66 ... ok
17/67 ... ok
17/68 ... ok
17/69 ... ok
17/70 ... ok
17/71 ... ok
17/72 ... ok
17/73 ... ok
17/74 ... ok
17/75 ... ok
17/76 ... ok
21/77 ... ok
22/78 ... ok
23/79 ... ok
24/80 ... ok
19/81 ... ok
41/87 ... ok
33/98 ... ok
9/99 ... ok
40/100 ... ok
40/101 ... ok
45/102 ... ok
11/103 ... ok
10/104 ... ok
40/105 ... ok
40/107 ... ok
41/108 ... ok
19/109 ... ok
Running /opt/gitlab/embedded/service/gitlab-shell/bin/check
Check GitLab API access: OK
Redis available via internal API: OK


Access to /gitlab-data/ssh/authorized_keys: OK
gitlab-shell self-check successful


Checking GitLab Shell ... Finished


Checking Sidekiq ...


Running? ... yes
Number of Sidekiq processes ... 1


Checking Sidekiq ... Finished


Reply by email is disabled in config/gitlab.yml
Checking LDAP ...


LDAP is disabled in config/gitlab.yml


Checking LDAP ... Finished


Checking GitLab ...


Git configured correctly? ... yes
Database config exists? ... yes
All migrations up? ... yes
Database contains orphaned GroupMembers? ... no
GitLab config exists? ... yes
GitLab config up to date? ... yes
Log directory writable? ... yes
Tmp directory writable? ... yes
Uploads directory exists? ... yes
Uploads directory has correct permissions? ... yes
Uploads directory tmp has correct permissions? ... yes
Init script exists? ... skipped (omnibus-gitlab has no init script)
Init script up-to-date? ... skipped (omnibus-gitlab has no init script)
Projects have namespace: ...
9/2 ... yes
8/5 ... yes
12/9 ... yes
16/10 ... yes
19/43 ... yes
20/44 ... yes
17/48 ... yes
17/49 ... yes
17/50 ... yes
17/51 ... yes
17/52 ... yes
17/53 ... yes
17/54 ... yes
17/55 ... yes
17/56 ... yes
17/57 ... yes
17/58 ... yes
17/59 ... yes
17/60 ... yes
17/61 ... yes
17/62 ... yes
17/63 ... yes
17/64 ... yes
17/65 ... yes
17/66 ... yes
17/67 ... yes
17/68 ... yes
17/69 ... yes
17/70 ... yes
17/71 ... yes
17/72 ... yes
17/73 ... yes
17/74 ... yes
17/75 ... yes
17/76 ... yes
21/77 ... yes
22/78 ... yes
23/79 ... yes
24/80 ... yes
19/81 ... yes
41/87 ... yes
33/98 ... yes
9/99 ... yes
40/100 ... yes
40/101 ... yes
45/102 ... yes
11/103 ... yes
10/104 ... yes
40/105 ... yes
40/107 ... yes
41/108 ... yes
19/109 ... yes
Redis version >= 2.8.0? ... yes
Ruby version >= 2.3.3 ? ... yes (2.3.5)
Git version >= 2.7.3 ? ... yes (2.13.5)
Git user has default SSH configuration? ... yes
Active users: ... 31


Checking GitLab ... Finished