LFS PDF Preview error with S3 backend and proxy_download off

Summary

If the LFS storage is set to S3 Object Storage, and the proxy_download is set to false (which is the default), then the PDF files uploaded to LFS cannot be previewed.

The error reported by the frontend is An error occurred while loading the file. Please try again later.

The S3 URL given to the frontend works fine as I tried to download that file directly, but the previewing function cannot fetch from that URL for some reason.

Steps to reproduce

• On a self-hosted instance, use S3 to host LFS file and set proxy_download to false.
• Upload a PDF with LFS
• Try to preview that PDF on the Web

Example Project

https://lab.rongyi.io/LER0ever/pdf-preview-issue (public)

There are 4 files in the repo:

• PDF-Normal.pdf: control group for local PDF file previewing, works fine
• PDF-LFS.pdf: cannot preview with error mentioned above
• PNG-Normal.png: control group for local PNG file previewing, works fine
• PNG-LFS.png: control group for LFS PNG file previewing, works fine

And PDF-LFS.pdf is the only file that cannot be previewed.

PDF-Normal.pdf serves as a control group to show that PDF previewing is working, and PNG-LFS.png serves as a control group for LFS file previewing.

However, I cannot reproduce this issue on GitLab.com, because it seems that GitLab.com has proxy_download set to true, the attempt is at https://gitlab.com/LER0ever/pdf-preview-issue

What is the current bug behavior?

PDF Preview page gives an error:

An error occurred while loading the file. Please try again later.

What is the expected correct behavior?

The preview of that LFS-hosted PDF should appear

Relevant logs and/or screenshots

Output of checks

TLDR: docker omnibus installation, on tag 13.3.0-ee

Results of GitLab environment info

Expand for output related to GitLab environment info

(For installations with omnibus-gitlab package run and paste the output of:
`sudo gitlab-rake gitlab:env:info`)

(For installations from source run and paste the output of:
`sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production`)

root@rongyi-srv-lab:~# docker exec -t root_gitlab_1 gitlab-rake gitlab:env:info

System information
System:
Proxy:          no
Current User:   git
Using RVM:      no
Ruby Version:   2.6.6p146
Gem Version:    2.7.10
Bundler Version:1.17.3
Rake Version:   12.3.3
Redis Version:  5.0.9
Git Version:    2.28.0
Sidekiq Version:5.2.9
Go Version:     unknown

GitLab information
Version:        13.3.0-ee
Revision:       4922d2720ac
Directory:      /opt/gitlab/embedded/service/gitlab-rails
DB Adapter:     PostgreSQL
DB Version:     11.7
URL:            https://lab.rongyi.io
HTTP Clone URL: https://lab.rongyi.io/some-group/some-project.git
SSH Clone URL:  ssh://git@lab.rongyi.io:233/some-group/some-project.git
Elasticsearch:  no
Geo:            no
Using LDAP:     no
Using Omniauth: yes
Omniauth Providers: google_oauth2

GitLab Shell
Version:        13.6.0
Repository storage paths:
- default:      /var/opt/gitlab/git-data/repositories
GitLab Shell path:              /opt/gitlab/embedded/service/gitlab-shell
Git:            /opt/gitlab/embedded/bin/git

Results of GitLab application Check

Expand for output related to the GitLab application check

(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:check SANITIZE=true)
(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)
(we will only investigate if the tests are passing)
root@rongyi-srv-lab:~# docker exec -t root_gitlab_1 gitlab-rake gitlab:check SANITIZE=true
Checking GitLab subtasks ...
Checking GitLab Shell ...
GitLab Shell: ... GitLab Shell version >= 13.6.0 ? ... OK (13.6.0)
Running /opt/gitlab/embedded/service/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? ... skipped (omnibus-gitlab has no init script)
Init script up-to-date? ... skipped (omnibus-gitlab has no init script)
Projects have namespace: ...
40/1 ... yes
42/2 ... yes
42/3 ... yes
35/4 ... yes
43/5 ... yes
34/6 ... yes
47/7 ... yes
45/8 ... yes
46/9 ... yes
46/10 ... yes
45/11 ... yes
46/12 ... yes
40/13 ... yes
46/14 ... yes
46/15 ... yes
53/16 ... yes
53/17 ... yes
46/18 ... yes
44/19 ... yes
44/20 ... yes
44/21 ... yes
44/22 ... yes
37/23 ... yes
40/24 ... yes
40/25 ... yes
42/26 ... yes
35/27 ... yes
57/29 ... yes
57/30 ... yes
58/32 ... yes
56/33 ... yes
59/34 ... yes
59/35 ... yes
59/36 ... yes
40/38 ... yes
54/39 ... yes
62/40 ... yes
63/41 ... yes
63/42 ... yes
65/43 ... yes
64/44 ... yes
40/45 ... yes
47/46 ... yes
62/47 ... yes
64/48 ... yes
66/49 ... yes
66/50 ... yes
66/51 ... yes
68/52 ... yes
62/53 ... yes
40/54 ... yes
62/56 ... yes
52/57 ... yes
62/58 ... yes
71/59 ... yes
71/60 ... yes
40/61 ... yes
57/62 ... yes
73/63 ... yes
73/64 ... yes
40/65 ... yes
40/66 ... yes
40/67 ... yes
72/68 ... yes
72/69 ... yes
40/70 ... yes
40/71 ... yes
43/72 ... yes
43/73 ... yes
72/74 ... yes
80/75 ... yes
80/76 ... yes
80/77 ... yes
80/78 ... yes
80/79 ... yes
80/80 ... yes
62/81 ... yes
57/82 ... yes
62/83 ... yes
73/84 ... yes
82/85 ... yes
56/86 ... yes
57/87 ... yes
72/88 ... yes
56/89 ... yes
82/90 ... yes
84/91 ... yes
85/92 ... yes
82/93 ... yes
65/94 ... yes
92/95 ... yes
84/96 ... yes
84/97 ... yes
84/98 ... yes
68/99 ... yes
87/100 ... yes
87/101 ... yes
73/102 ... yes
57/103 ... yes
63/104 ... yes
56/105 ... yes
78/106 ... yes
88/107 ... yes
73/108 ... yes
82/109 ... yes
89/110 ... yes
82/111 ... yes
82/112 ... yes
52/113 ... yes
45/114 ... yes
57/115 ... yes
91/116 ... yes
91/117 ... yes
46/118 ... yes
46/119 ... yes
92/120 ... yes
92/121 ... yes
92/122 ... yes
92/123 ... yes
92/124 ... yes
90/125 ... yes
60/126 ... yes
60/127 ... yes
60/128 ... yes
91/129 ... yes
71/130 ... yes
71/131 ... yes
80/132 ... yes
40/133 ... yes
40/134 ... yes
40/135 ... yes
41/136 ... yes
41/137 ... yes
93/138 ... yes
35/139 ... yes
Redis version >= 4.0.0? ... yes
Ruby version >= 2.5.3 ? ... yes (2.6.6)
Git version >= 2.24.0 ? ... yes (2.28.0)
Git user has default SSH configuration? ... yes
Active users: ... 1
Is authorized keys file accessible? ... yes
GitLab configured to store new projects in hashed storage? ... yes
All projects are in hashed storage? ... yes
Elasticsearch version 6.x - 7.x? ... skipped (elasticsearch is disabled)
Checking GitLab App ... Finished
Checking GitLab subtasks ... Finished

Possible fixes