gitlab-org--gitlab-foss/doc/development/file_storage.md
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# File Storage in GitLab
We use the [CarrierWave] gem to handle file upload, store and retrieval.
There are many places where file uploading is used, according to contexts:
- System
- Instance Logo (logo visible in sign in/sign up pages)
- Header Logo (one displayed in the navigation bar)
- Group
- Group avatars
- User
- User avatars
- User snippet attachments
- Project
- Project avatars
- Issues/MR/Notes Markdown attachments
- Issues/MR/Notes Legacy Markdown attachments
- CI Artifacts (archive, metadata, trace)
- LFS Objects
- Merge request diffs
## Disk storage
GitLab started saving everything on local disk. While directory location changed from previous versions,
they are still not 100% standardized. You can see them below:
| Description | In DB? | Relative path (from CarrierWave.root) | Uploader class | model_type |
| ------------------------------------- | ------ | ----------------------------------------------------------- | ---------------------- | ---------- |
| Instance logo | yes | uploads/-/system/appearance/logo/:id/:filename | `AttachmentUploader` | Appearance |
| Header logo | yes | uploads/-/system/appearance/header_logo/:id/:filename | `AttachmentUploader` | Appearance |
| Group avatars | yes | uploads/-/system/group/avatar/:id/:filename | `AvatarUploader` | Group |
| User avatars | yes | uploads/-/system/user/avatar/:id/:filename | `AvatarUploader` | User |
| User snippet attachments | yes | uploads/-/system/personal_snippet/:id/:random_hex/:filename | `PersonalFileUploader` | Snippet |
| Project avatars | yes | uploads/-/system/project/avatar/:id/:filename | `AvatarUploader` | Project |
| Issues/MR/Notes Markdown attachments | yes | uploads/:project_path_with_namespace/:random_hex/:filename | `FileUploader` | Project |
| Issues/MR/Notes Legacy Markdown attachments | no | uploads/-/system/note/attachment/:id/:filename | `AttachmentUploader` | Note |
| CI Artifacts (CE) | yes | shared/artifacts/:disk_hash[0..1]/:disk_hash[2..3]/:disk_hash/:year_:month_:date/:job_id/:job_artifact_id (:disk_hash is SHA256 digest of project_id) | `JobArtifactUploader` | Ci::JobArtifact |
| LFS Objects (CE) | yes | shared/lfs-objects/:hex/:hex/:object_hash | `LfsObjectUploader` | LfsObject |
| External merge request diffs | yes | shared/external-diffs/merge_request_diffs/mr-:parent_id/diff-:id | `ExternalDiffUploader` | MergeRequestDiff |
CI Artifacts and LFS Objects behave differently in CE and EE. In CE they inherit the `GitlabUploader`
while in EE they inherit the `ObjectStorage` and store files in and S3 API compatible object store.
In the case of Issues/MR/Notes Markdown attachments, there is a different approach using the [Hashed Storage] layout,
instead of basing the path into a mutable variable `:project_path_with_namespace`, it's possible to use the
hash of the project ID instead, if project migrates to the new approach (introduced in 10.2).
> Note: We provide an [all-in-one rake task] to migrate all uploads to object
> storage in one go. If a new Uploader class or model type is introduced, make
> sure you add a rake task invocation corresponding to it to the [category
> list].
### Path segments
Files are stored at multiple locations and use different path schemes.
All the `GitlabUploader` derived classes should comply with this path segment schema:
```
| GitlabUploader
| ----------------------- + ------------------------- + --------------------------------- + -------------------------------- |
| `<gitlab_root>/public/` | `uploads/-/system/` | `user/avatar/:id/` | `:filename` |
| ----------------------- + ------------------------- + --------------------------------- + -------------------------------- |
| `CarrierWave.root` | `GitlabUploader.base_dir` | `GitlabUploader#dynamic_segment` | `CarrierWave::Uploader#filename` |
| | `CarrierWave::Uploader#store_dir` | |
| FileUploader
| ----------------------- + ------------------------- + --------------------------------- + -------------------------------- |
| `<gitlab_root>/shared/` | `artifacts/` | `:year_:month/:id` | `:filename` |
| `<gitlab_root>/shared/` | `snippets/` | `:secret/` | `:filename` |
| ----------------------- + ------------------------- + --------------------------------- + -------------------------------- |
| `CarrierWave.root` | `GitlabUploader.base_dir` | `GitlabUploader#dynamic_segment` | `CarrierWave::Uploader#filename` |
| | `CarrierWave::Uploader#store_dir` | |
| | | `FileUploader#upload_path |
| ObjectStore::Concern (store = remote)
| ----------------------- + ------------------------- + ----------------------------------- + -------------------------------- |
| `<bucket_name>` | <ignored> | `user/avatar/:id/` | `:filename` |
| ----------------------- + ------------------------- + ----------------------------------- + -------------------------------- |
| `#fog_dir` | `GitlabUploader.base_dir` | `GitlabUploader#dynamic_segment` | `CarrierWave::Uploader#filename` |
| | | `ObjectStorage::Concern#store_dir` | |
| | | `ObjectStorage::Concern#upload_path |
```
The `RecordsUploads::Concern` concern will create an `Upload` entry for every file stored by a `GitlabUploader` persisting the dynamic parts of the path using
`GitlabUploader#dynamic_path`. You may then use the `Upload#build_uploader` method to manipulate the file.
## Object Storage
By including the `ObjectStorage::Concern` in the `GitlabUploader` derived class, you may enable the object storage for this uploader. To enable the object storage
in your uploader, you need to either 1) include `RecordsUpload::Concern` and prepend `ObjectStorage::Extension::RecordsUploads` or 2) mount the uploader and create a new field named `<mount>_store`.
The `CarrierWave::Uploader#store_dir` is overridden to
- `GitlabUploader.base_dir` + `GitlabUploader.dynamic_segment` when the store is LOCAL
- `GitlabUploader.dynamic_segment` when the store is REMOTE (the bucket name is used to namespace)
### Using `ObjectStorage::Extension::RecordsUploads`
> Note: this concern will automatically include `RecordsUploads::Concern` if not already included.
The `ObjectStorage::Concern` uploader will search for the matching `Upload` to select the correct object store. The `Upload` is mapped using `#store_dirs + identifier` for each store (LOCAL/REMOTE).
```ruby
class SongUploader < GitlabUploader
include RecordsUploads::Concern
include ObjectStorage::Concern
prepend ObjectStorage::Extension::RecordsUploads
...
end
class Thing < ActiveRecord::Base
mount :theme, SongUploader # we have a great theme song!
...
end
```
### Using a mounted uploader
The `ObjectStorage::Concern` will query the `model.<mount>_store` attribute to select the correct object store.
This column must be present in the model schema.
```ruby
class SongUploader < GitlabUploader
include ObjectStorage::Concern
...
end
class Thing < ActiveRecord::Base
attr_reader :theme_store # this is an ActiveRecord attribute
mount :theme, SongUploader # we have a great theme song!
def theme_store
super || ObjectStorage::Store::LOCAL
end
...
end
```
[CarrierWave]: https://github.com/carrierwaveuploader/carrierwave
[Hashed Storage]: ../administration/repository_storage_types.md
[all-in-one rake task]: ../administration/raketasks/uploads/migrate.md
[category list]: https://gitlab.com/gitlab-org/gitlab-ce/blob/master/lib/tasks/gitlab/uploads/migrate.rake