Unable to remove empty/dead default metric groups

Summary

The huge collection of default metrics are forced upon users even when they are empty/unused and/or not applicable at all (Nginx for a C++ project, AWS for a project containing only .md files, ...)

Steps to reproduce

Set up a new self hosted GitLab instance, activated the Metrics subsystem and supply a custom, external Prometheus server (I am not sure whether the problem only shows up using those steps or if the problem always occurs)

Example Project

Not applicable, as it happens in self hosted instance. Our instance is running 13.0.6. Our instance can not be accessed publicly.

What is the current bug behavior?

When I activate Prometheus support for a project, my Operations/Metrics default dashboard is bogged down with tons of empty groups that don't make sense for the project. Our own custom metrics are pushed all the way down:

All these groups are empty:

What is the expected correct behavior?

Empty groups for technologies that aren't in use should not be forced into the default metrics' prime real estate, pushing actual metrics off the page.

Results of GitLab environment info

Expand for output related to GitLab environment info

System information
System:
Current User:   git
Using RVM:      no
Ruby Version:   2.6.5p114
Gem Version:    3.0.3
Bundler Version:1.17.3
Rake Version:   12.3.3
Redis Version:  4.0.9
Git Version:    2.27.0
Sidekiq Version:5.2.7
Go Version:     unknown

GitLab information
Version:        13.0.6
Revision:       5aa982e01ea
Directory:      /home/git/gitlab
DB Adapter:     PostgreSQL
DB Version:     11.8
URL:            http://:10080
HTTP Clone URL: http://:10080/some-group/some-project.git
SSH Clone URL:  ssh://git@:10022/some-group/some-project.git
Using LDAP:     no
Using Omniauth: no

GitLab Shell
Version:        13.2.0
Repository storage paths:
- default:      /home/git/data/repositories
GitLab Shell path:              /home/git/gitlab-shell
Git:            /usr/bin/git

Results of GitLab application Check

Note: I can't migrate all our projects right now, but I am very certain that the comment about the hashed storage is not related to the bug I am reporting.

Expand for output related to the GitLab application check

Checking GitLab subtasks ...
Checking GitLab Shell ...
GitLab Shell: ... GitLab Shell version >= 13.2.0 ? ... OK (13.2.0)
Running /home/git/gitlab-shell/bin/check
Internal API available: OK
Redis available via internal API: OK
gitlab-shell self-check successful
Checking GitLab Shell ... Finished
Checking Gitaly ...
Gitaly: ... default ... OK
Checking Gitaly ... Finished
Checking Sidekiq ...
Sidekiq: ... Running? ... yes
Number of Sidekiq processes ... 1
Checking Sidekiq ... Finished
Checking Incoming Email ...
Incoming Email: ... Reply by email is disabled in config/gitlab.yml
Checking Incoming Email ... Finished
Checking LDAP ...
LDAP: ... LDAP is disabled in config/gitlab.yml
Checking LDAP ... Finished
Checking GitLab App ...
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? ... yes
Init script up-to-date? ... yes
Projects have namespace: ...
4/1 ... yes
13/2 ... yes
9/4 ... yes
13/7 ... yes
18/8 ... yes
18/11 ... yes
4/14 ... yes
9/15 ... yes
4/16 ... yes
9/17 ... yes
20/21 ... yes
3/22 ... yes
4/23 ... yes
4/24 ... yes
9/27 ... yes
20/31 ... yes
22/33 ... yes
23/34 ... yes
23/35 ... yes
13/36 ... yes
20/37 ... yes
22/38 ... yes
20/39 ... yes
24/40 ... yes
4/41 ... yes
4/42 ... yes
9/43 ... yes
9/44 ... yes
9/45 ... yes
9/46 ... yes
20/47 ... yes
20/48 ... yes
20/49 ... yes
20/50 ... yes
20/51 ... yes
20/52 ... yes
13/53 ... yes
13/54 ... yes
22/55 ... yes
25/57 ... yes
22/59 ... yes
13/60 ... yes
13/61 ... yes
13/62 ... yes
13/63 ... yes
13/64 ... yes
13/65 ... yes
25/66 ... yes
13/67 ... yes
24/68 ... yes
22/69 ... yes
22/70 ... yes
24/71 ... yes
20/72 ... yes
22/73 ... yes
24/74 ... yes
26/75 ... yes
26/76 ... yes
28/77 ... yes
28/78 ... yes
28/79 ... yes
28/80 ... yes
28/81 ... yes
28/82 ... yes
28/83 ... yes
28/84 ... yes
28/85 ... yes
28/86 ... yes
28/87 ... yes
28/88 ... yes
26/89 ... yes
27/90 ... yes
27/91 ... yes
27/92 ... yes
27/93 ... yes
27/94 ... yes
27/95 ... yes
27/96 ... yes
27/97 ... yes
27/98 ... yes
27/99 ... yes
27/100 ... yes
27/101 ... yes
27/102 ... yes
27/103 ... yes
20/104 ... yes
27/105 ... yes
27/106 ... yes
27/107 ... yes
1/108 ... yes
24/109 ... yes
13/110 ... yes
20/111 ... yes
20/112 ... yes
32/118 ... yes
32/120 ... yes
30/121 ... yes
22/123 ... yes
22/124 ... yes
22/129 ... yes
20/130 ... yes
18/132 ... yes
28/133 ... yes
22/134 ... yes
9/138 ... yes
9/139 ... yes
18/141 ... yes
18/142 ... yes
18/143 ... yes
13/147 ... yes
36/150 ... yes
37/151 ... yes
37/152 ... yes
4/153 ... yes
20/154 ... yes
9/156 ... yes
4/158 ... yes
20/159 ... yes
2/160 ... yes
2/161 ... yes
18/162 ... yes
4/163 ... yes
2/164 ... yes
2/165 ... yes
9/166 ... yes
26/167 ... yes
28/168 ... yes
28/169 ... yes
22/170 ... yes
25/171 ... yes
2/174 ... yes
2/175 ... yes
2/177 ... yes
4/178 ... yes
9/179 ... yes
4/180 ... yes
42/182 ... yes
2/183 ... yes
Redis version >= 4.0.0? ... yes
Ruby version >= 2.5.3 ? ... yes (2.6.5)
Git version >= 2.22.0 ? ... yes (2.27.0)
Git user has default SSH configuration? ... yes
Active users: ... 12
Is authorized keys file accessible? ... yes
GitLab configured to store new projects in hashed storage? ... yes
All projects are in hashed storage? ... no
Try fixing it:
Please migrate all projects to hashed storage
as legacy storage is deprecated in 13.0 and support will be removed in 14.0.
For more information see:
doc/administration/repository_storage_types.md
Checking GitLab App ... Finished
Checking GitLab subtasks ... Finished