feat(server): Automatic watching of library folders (#6192)

* feat: initial watch support

* allow offline files

* chore: ignore query errors when resetting e2e db

* revert db query

* add savepoint

* guard the user query

* chore: openapi and db migration

* wip

* support multiple libraries

* fix tests

* wip

* can now cleanup chokidar watchers

* fix unit tests

* add library watch queue

* add missing init from merge

* wip

* can now filter file extensions

* remove watch api from non job client

* Fix e2e test

* watch library with updated import path and exclusion pattern

* add library watch frontend ui

* case sensitive watching extensions

* can auto watch libraries

* move watcher e2e tests to separate file

* don't watch libraries from a queue

* use event emitters

* shorten e2e test timeout

* refactor chokidar code to filesystem provider

* expose chokidar parameters to config file

* fix storage mock

* set default config for library watching

* add fs provider mocks

* cleanup

* add more unit tests for watcher

* chore: fix format + sql

* add more tests

* move unwatch feature back to library service

* add file event unit tests

* chore: formatting

* add documentation

* fix e2e tests

* chore: fix e2e tests

* fix library updating

* test cleanup

* fix typo

* cleanup

* fixing as per pr comments

* reduce library watch config file

* update storage config and mocks

* move negative event tests to unit tests

* fix library watcher e2e

* make watch configuration global

* remove the feature flag

* refactor watcher teardown

* fix microservices init

* centralize asset scan job queue

* improve docs

* add more tests

* chore: open api

* initialize app service

* fix docs

* fix library watch feature flag

* Update docs/docs/features/libraries.md

Co-authored-by: Daniel Dietzler <36593685+danieldietzler@users.noreply.github.com>

* fix: import right app service

* don't be truthy

* fix test speling

* stricter library update tests

* move fs watcher mock to external file

* subscribe to config changes

* docker does not need polling

* make library watch() private

* feat: add configuration ui

---------

Co-authored-by: Daniel Dietzler <36593685+danieldietzler@users.noreply.github.com>
Co-authored-by: Alex Tran <alex.tran1502@gmail.com>

docs/docs/features/libraries.md

@@ -72,7 +72,7 @@ For security purposes, each Immich user is disallowed to add external files by d
 
 With the `external path` set, a user is restricted to accessing external files to files or directories within that path. The Immich admin should still be careful not set the external path too generously. For example, `user1` wants to read their photos in to `/home/user1`. A lazy admin sets that user's external path to `/home/` since it "gets the job done". However, that user will then be able to read all photos in `/home/user2/private-photos`, too! Please set the external path as specific as possible. If multiple folders must be added, do this using the docker volume mount feature described below.
 
-### Exclusion Patterns and Scan Settings
+### Exclusion Patterns
 
 By default, all files in the import paths will be added to the library. If there are files that should not be added, exclusion patterns can be used to exclude them. Exclusion patterns are glob patterns are matched against the full file path. If a file matches an exclusion pattern, it will not be added to the library. Exclusion patterns can be added in the Scan Settings page for each library. Under the hood, Immich uses the [glob](https://www.npmjs.com/package/glob) package to match patterns, so please refer to [their documentation](https://github.com/isaacs/node-glob#glob-primer) to see what patterns are supported.
 
@@ -83,6 +83,15 @@ Some basic examples:
 - `**/Raw/**` will exclude all files in any directory named `Raw`
 - `**/*.{tif,jpg}` will exclude all files with the extension `.tif` or `.jpg`
 
+### Automatic watching (EXPERIMENTAL)
+
+This feature - currently hidden in the config file - is considered experimental and for advanced users only. If enabled, it will allow automatic watching of the filesystem which means new assets are automatically imported to Immich without needing to rescan. Deleted assets are, as always, marked as offline and can be removed with the "Remove offline files" button.
+
+If your photos are on a network drive you will likely have to enable filesystem polling. The performance hit for polling large libraries is currently unknown, feel free to test this feature and report back. In addition to the boolean feature flag, the configuration file allows customization of the following parameters, please see the [chokidar documentation](https://github.com/paulmillr/chokidar?tab=readme-ov-file#performance) for reference.
+
+- `usePolling` (default: `false`).
+- `interval`. (default: 10000). When using polling, this is how often (in milliseconds) the filesystem is polled.
+
 ### Nightly job
 
 There is an automatic job that's run once a day and refreshes all modified files in all libraries as well as cleans up any libraries stuck in deletion.