- Added general authentication that seperates user calles from a gateway and cron scheduler updates

- Added notifications being seperate by user_id
- Added user paths to subscribe/unsubscribe from a repository
- Cleaned up main.py by moving handlers to its own module

database.sql

@@ -0,0 +1,28 @@
+CREATE TABLE `watched_repositories` (
+  `id` int unsigned NOT NULL AUTO_INCREMENT,
+  `type` enum('github','dockerhub') COLLATE utf8mb4_unicode_ci NOT NULL,
+  `org` varchar(39) COLLATE utf8mb4_unicode_ci NOT NULL,
+  `repo` varchar(100) COLLATE utf8mb4_unicode_ci NOT NULL,
+  `tag` varchar(128) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin NOT NULL,
+  `latest_entry` varchar(255) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
+  `active` tinyint(1) NOT NULL DEFAULT '1',
+  `missing_checks` tinyint unsigned NOT NULL DEFAULT '0',
+  `created_at` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  PRIMARY KEY (`id`),
+  UNIQUE KEY `uq_repository` (`type`,`org`,`repo`,`tag`),
+  KEY `idx_active_type` (`active`,`type`)
+) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
+
+CREATE TABLE `watched_repositories_subscriptions` (
+  `id` int unsigned NOT NULL AUTO_INCREMENT,
+  `user_id` bigint NOT NULL,
+  `repository_id` int unsigned NOT NULL,
+  `custom_name` varchar(255) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
+  `active` tinyint(1) NOT NULL DEFAULT '1',
+  `created_at` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  PRIMARY KEY (`id`),
+  UNIQUE KEY `uq_user_repository` (`user_id`,`repository_id`),
+  KEY `idx_repository_active` (`repository_id`,`active`),
+  CONSTRAINT `fk_wrs_repository` FOREIGN KEY (`repository_id`) REFERENCES `watched_repositories` (`id`) ON DELETE CASCADE,
+  CONSTRAINT `fk_wrs_user` FOREIGN KEY (`user_id`) REFERENCES `users` (`user_id`) ON DELETE CASCADE
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci ;

src/handlers.py

@@ -0,0 +1,66 @@
+from fastapi import FastAPI, Request
+from fastapi.exceptions import RequestValidationError
+from fastapi.responses import JSONResponse
+from starlette.middleware.base import BaseHTTPMiddleware
+
+from metrics_server import REQUEST_COUNTER
+from repository_errors import RepositoryError
+from simple_logger_handler import setup_logger
+
+logger = setup_logger(__name__)
+
+
+async def repository_error_handler(request: Request, exc: RepositoryError):
+	log = logger.warning if exc.client_visible else logger.error
+	log(f"[FastAPI] {request.method} {request.url.path} failed: {exc}")
+	return JSONResponse(
+		status_code=exc.status_code,
+		content={"code": exc.code, "detail": exc.client_message},
+	)
+
+
+async def validation_error_handler(request: Request, exc: RequestValidationError):
+	errors = exc.errors()
+
+	for err in errors:
+		original = (err.get("ctx") or {}).get("error")
+		if isinstance(original, RepositoryError):
+			return JSONResponse(
+				status_code=original.status_code,
+				content={"code": original.code, "detail": original.client_message},
+			)
+
+	# Problems in headers, path or query are the calling service's fault, not the user's
+	if any(err["loc"][0] != "body" for err in errors):
+		logger.error(f"[FastAPI] Invalid request from a calling service: {[(e['loc'], e['msg']) for e in errors]}")
+		return JSONResponse(status_code=400, content={"code": "bad_request", "detail": "The request could not be processed"})
+
+	messages = []
+	for err in errors:
+		field = ".".join(str(p) for p in err["loc"] if p != "body")
+		msg = err["msg"].removeprefix("Value error, ")
+		messages.append(f"{field}: {msg}" if field else msg)
+	return JSONResponse(status_code=422, content={"code": "validation_error", "detail": "; ".join(messages)})
+
+
+async def prometheus_middleware(request: Request, call_next):
+	logger.debug(f"[FastAPI] Incoming request: {request.method} {request.url.path}")
+	status = 500
+	try:
+		response = await call_next(request)
+		status = response.status_code
+		logger.debug(f"[FastAPI] Request processed with status {status}")
+	except Exception as e:
+		logger.error(f"[FastAPI] Exception occurred: {e}", exc_info=True)
+		raise
+	finally:
+		REQUEST_COUNTER.labels(request.method, request.url.path, status).inc()
+		logger.debug(f"[FastAPI] Counter incremented for {request.method} {request.url.path} [{status}]")
+	return response
+
+
+def register_handlers(app: FastAPI) -> None:
+	"""Attach the error handlers and the metrics middleware to the app."""
+	app.add_exception_handler(RepositoryError, repository_error_handler)
+	app.add_exception_handler(RequestValidationError, validation_error_handler)
+	app.add_middleware(BaseHTTPMiddleware, dispatch=prometheus_middleware)

src/main.py

@@ -3,20 +3,33 @@ import os
 from contextlib import asynccontextmanager
 
 import uvicorn
-from fastapi import APIRouter, Depends, FastAPI, HTTPException, Request, Response
+from fastapi import APIRouter, Depends, FastAPI, HTTPException, Request
+from service_auth import UserId
 
 from auth_config import Caller, auth
 from db_module import close_connection_pool, create_connection_pool, get_db, start_healthcheck_thread
-from dockerhub_api import find_package_version_with_tag as find_package_version_with_tag_dockerhub
-from github_api import find_package_version_with_tag as find_package_version_with_tag_github
-from metrics_server import REQUEST_COUNTER, metrics_api
+from handlers import register_handlers
+from metrics_server import metrics_api
+from models import RepositoryType, RepositoryUpdate
+from repositories import (
+	fetch_latest,
+	reset_missing_checks,
+	unsubscribe_every_subscriber_from_repository,
+	validate_repository_combination_and_return_latest_tag,
+)
+from repository_errors import (
+	ApiAuthenticationFailure,
+	RateLimitedError,
+	RepositoryApiError,
+	RepositoryNotFoundError,
+	RepositoryTagNotFoundError,
+)
 from secret_manager import cleanup_secret_files
-from send_notifications import NotificationClient
+from send_notifications import NotificationClient, NotificationError, NotificationUnavailableError
 from simple_logger_handler import LOG_LEVEL, setup_logger
 
 logger = setup_logger(__name__)
 
-
 @asynccontextmanager
 async def lifespan(app: FastAPI):
 	logger.info("[FastAPI] Starting application...")
@@ -51,103 +64,218 @@ api = FastAPI(
 		dependencies=[Depends(auth.authenticate)],
 )
 
-@api.middleware("http")
-async def prometheus_middleware(request: Request, call_next):
-	logger.debug(f"[FastAPI] Incoming request: {request.method} {request.url.path}")
-	status = 500
-	try:
-		response = await call_next(request)
-		status = response.status_code
-		logger.debug(f"[FastAPI] Request processed with status {status}")
-	except Exception as e:
-		logger.error(f"[FastAPI] Exception occurred: {e}", exc_info=True)
-		raise
-	finally:
-		REQUEST_COUNTER.labels(request.method, request.url.path, status).inc()
-		logger.debug(f"[FastAPI] Counter incremented for {request.method} {request.url.path} [{status}]")
-	return response
-
+register_handlers(api)
 user_router = APIRouter(dependencies=[Depends(auth.require(Caller.GATEWAY))])
 scheduler_router = APIRouter(dependencies=[Depends(auth.require(Caller.SCHEDULER))])
 
-@scheduler_router.post("/github")
-def handle_suwayomi(
+
+@scheduler_router.post("/update/{repository_type}")
+def update_watched_repositories(
 	request: Request,
-		db = Depends(get_db)
+	repository_type: RepositoryType,
+	db=Depends(get_db),
 	):
+	results = {"checked": 0, "new": 0, "errors": 0}
+	with db.cursor() as cursor:
+		cursor.execute(
+			"SELECT id, org, repo, tag, latest_entry, missing_checks "
+			"FROM watched_repositories WHERE type = %s AND active = 1",
+			(repository_type.value,),
+		)
+		repositories = cursor.fetchall()
+	logger.debug(f"[FastAPI] Found {len(repositories)} active {repository_type.value} repositories to check.")
+
+	for repository_id, org, repo, tag, latest_entry, missing_checks in repositories:
+		results["checked"] += 1
+		try:
+			online_version = fetch_latest(repository_type, org, repo, tag)
+		except RateLimitedError as e:
+			logger.warning(f"[FastAPI] Rate limited, stopping the {repository_type.value} check: {e}")
+			results["errors"] += 1
+			break
+		except ApiAuthenticationFailure as e:
+			logger.error(f"[FastAPI] {e}")
+			results["errors"] += 1
+			break
+		except (RepositoryNotFoundError, RepositoryTagNotFoundError) as e:
+			logger.warning(f"[FastAPI] {e}, deactivating repository ID {repository_id}")
+			unsubscribe_every_subscriber_from_repository(db, request.app.state.notifier, repository_id, org, repo, tag)
+			continue
+		except RepositoryApiError as e:
+			logger.warning(f"[FastAPI] Lookup failed for ID {repository_id}: {e}")
+			results["errors"] += 1
+			continue
+		except Exception:
+			logger.exception(f"[FastAPI] Unexpected error for ID {repository_id} ({org}/{repo}:{tag})")
+			results["errors"] += 1
+			continue
+
+		if missing_checks:
+			reset_missing_checks(db, repository_id)
+		if latest_entry == online_version:
+			continue
 
 		try:
-		logger.info("[FastAPI] Suwayomi handler invoked")
-		online_version = find_package_version_with_tag_github("Suwayomi", "tachidesk", "stable")
-		logger.debug(f"[FastAPI] Fetched latest Suwayomi version from GitHub: {online_version}")
+
+			logger.info(f"[FastAPI] New version detected for org={org}, repo={repo}, tag={tag}")
 
 			with db.cursor() as cursor:
-			cursor.execute("SELECT latest_version FROM docker_repositories WHERE app='suwayomi'")
-			local_state = cursor.fetchone()
-			local_version = str(local_state[0]) if local_state and local_state[0] is not None else None
-			logger.debug(f"[FastAPI] Comparing versions: local='{local_version}' vs online='{online_version}'")
-
-			if local_version != online_version:
-				logger.debug("[FastAPI] Version mismatch detected. Updating database.")
-				cursor.execute ("UPDATE docker_repositories SET latest_version=%s WHERE app='suwayomi'",
-					(online_version,))
-				db.commit()
-				logger.info("[FastAPI] New Suwayomi version recorded in database")
-				request.app.state.notifier.send(
-					title="New Suwayomi version has been found",
-					body=f"Version {online_version}",
-					category="utility",
-					user_id=1,
+				cursor.execute(
+					"SELECT user_id, custom_name "
+					"FROM watched_repositories_subscriptions "
+					"WHERE repository_id = %s AND active = 1",
+					(repository_id,),
 				)
-				logger.debug("[FastAPI] Notification sent for Suwayomi update")
-				return Response(status_code=200)
+				subscribers = cursor.fetchall()
 
-		logger.debug("[FastAPI] No new Suwayomi version found")
-		return Response(status_code=204)
-
-	except Exception as e:
-		logger.error(f"[FastAPI] Error in Suwayomi handler: {e}", exc_info=True)
-		raise HTTPException(status_code=500, detail=str(e)) from e
-
-
-
-@scheduler_router.post("/dockerhub")
-def handle_pihole(
-		request: Request,
-		db = Depends(get_db)
-		):
+			sent = 0
+			failed = 0
+			for user_id, custom_name in subscribers:
 				try:
-		logger.info("[FastAPI] Pi-hole handler invoked")
-		online_version = find_package_version_with_tag_dockerhub("pihole/pihole", "latest")
-		logger.debug(f"[FastAPI] Fetched latest Pi-hole version from Docker Hub: {online_version}")
+					request.app.state.notifier.send(
+						title=custom_name or f"{org}/{repo}",
+						body=f"New version {online_version} for tag {tag}",
+						category="utility",
+						user_id=user_id,
+					)
+					sent += 1
+				except NotificationUnavailableError:
+					failed = len(subscribers) - sent
+					logger.error(
+						f"[FastAPI] Notifications backend unavailable, skipping "
+						f"{failed} remaining user(s) for repo={org}/{repo}"
+					)
+					break
+				except NotificationError as e:
+					failed += 1
+					logger.error(
+						f"[FastAPI] Failed to send notification to user_id={user_id} for repo={org}/{repo} "
+						f"status={getattr(e, 'status_code', None)}"
+					)
+
+			if subscribers and sent == 0:
+				results["errors"] += 1
+				logger.error(f"[FastAPI] All notifications failed for ID:{repository_id}, will retry later")
+				continue
 
 			with db.cursor() as cursor:
-			cursor.execute("SELECT latest_version FROM docker_repositories WHERE app='pihole'")
-			local_state = cursor.fetchone()
-			local_version = str(local_state[0]) if local_state and local_state[0] is not None else None
-			logger.debug(f"[FastAPI] Comparing versions: local='{local_version}' vs online='{online_version}'")
-
-			if local_version != online_version:
-				logger.debug("[FastAPI] Version mismatch detected. Updating database.")
-				cursor.execute ("UPDATE docker_repositories SET latest_version=%s WHERE app='pihole'",
-						(online_version,))
-				db.commit()
-				logger.info("[FastAPI] New Pi-hole version recorded in database")
-				request.app.state.notifier.send(
-					title="New Pi-hole version has been found",
-					body=f"Version {online_version}",
-					category="utility",
-					user_id=1,
+				cursor.execute(
+					"UPDATE watched_repositories SET latest_entry = %s WHERE id = %s",
+					(online_version, repository_id),
 				)
-				logger.debug("[FastAPI] Notification sent for Pi-hole update")
-				return Response(status_code=200)
-
-		logger.debug("[FastAPI] No new Pi-hole version found")
-		return Response(status_code=204)
+			db.commit()
+			logger.debug(f"[FastAPI] Notification sent and database updated for repository ID {repository_id}")
+			results["new"] += 1
 
 		except Exception as e:
-		logger.error(f"[FastAPI] Error in Pi-hole handler: {e}", exc_info=True)
-		raise HTTPException(status_code=500, detail=str(e)) from e
+			db.rollback()
+			results["errors"] += 1
+			logger.error(
+				f"[FastAPI] Failed for ID {repository_id} (org={org}, repo={repo}, tag={tag}): {e}",
+				exc_info=True,
+			)
+
+	if results["errors"]:
+		logger.warning(f"[FastAPI] {repository_type.value} check finished with errors: {results}")
+		raise HTTPException(status_code=500, detail=results)
+	logger.info(f"[FastAPI] {repository_type.value} check complete: {results}")
+	return results
+
+@user_router.post("/add/repository")
+def add_repository_subscription(
+	user_id: UserId,
+	repository: RepositoryUpdate,
+	db=Depends(get_db),
+):
+	name = f"{repository.org}/{repository.repo}:{repository.tag}"
+	logger.info(f"[FastAPI] Subscribe request: {repository.type.value} {name}, user_id={user_id}")
+
+	with db.cursor() as cursor:
+		cursor.execute(
+			"SELECT id, active FROM watched_repositories "
+			"WHERE type = %s AND org = %s AND repo = %s AND tag = %s",
+			(repository.type.value, repository.org, repository.repo, repository.tag),
+		)
+		known = cursor.fetchone()
+
+	latest_entry = None
+	if known is None or not known[1]:
+		latest_entry = validate_repository_combination_and_return_latest_tag(repository)
+
+	try:
+		with db.cursor() as cursor:
+			cursor.execute(
+				"INSERT INTO watched_repositories (type, org, repo, tag, latest_entry) "
+				"VALUES (%s, %s, %s, %s, %s) "
+				"ON DUPLICATE KEY UPDATE id = LAST_INSERT_ID(id), active = 1, missing_checks = 0, "
+				"latest_entry = COALESCE(VALUES(latest_entry), latest_entry)",
+				(repository.type.value, repository.org, repository.repo, repository.tag, latest_entry),
+			)
+			repository_id = cursor.lastrowid
+
+			cursor.execute(
+				"INSERT INTO watched_repositories_subscriptions (user_id, repository_id, custom_name) "
+				"VALUES (%s, %s, %s) "
+				"ON DUPLICATE KEY UPDATE active = 1, custom_name = VALUES(custom_name)",
+				(user_id, repository_id, repository.custom_name),
+			)
+		db.commit()
+	except Exception as e:
+		db.rollback()
+		logger.exception(f"[FastAPI] Failed to subscribe user_id={user_id} to {name}")
+		raise HTTPException(status_code=500) from e
+
+	logger.info(f"[FastAPI] user_id={user_id} subscribed to repository ID {repository_id} ({name})")
+	return {"status": "ok", "detail": "Subscribed to repository", "name": name}
+
+@user_router.post("/delete/repository")
+def delete_repository_subscription(
+	user_id: UserId,
+	repository: RepositoryUpdate,
+	db=Depends(get_db),
+):
+	name = f"{repository.org}/{repository.repo}:{repository.tag}"
+	logger.info(f"[FastAPI] Unsubscribe request: {repository.type.value} {name}, user_id={user_id}")
+
+	try:
+		with db.cursor() as cursor:
+			cursor.execute(
+				"SELECT id FROM watched_repositories "
+				"WHERE type = %s AND org = %s AND repo = %s AND tag = %s FOR UPDATE",
+				(repository.type.value, repository.org, repository.repo, repository.tag),
+			)
+			known = cursor.fetchone()
+
+			if known is None:
+				db.rollback()
+				logger.info(f"[FastAPI] Repository {repository.type.value} {name} is not tracked, nothing to do")
+				return {"status":"ok","detail":"Unsubscribed from repository","name":name}
+
+			repository_id = known[0]
+			cursor.execute(
+				"UPDATE watched_repositories_subscriptions SET active = 0 "
+				"WHERE user_id = %s AND repository_id = %s",
+				(user_id, repository_id),
+			)
+
+			cursor.execute(
+				"SELECT 1 from watched_repositories_subscriptions "
+				"WHERE repository_id = %s AND active = 1 LIMIT 1 FOR SHARE",
+				(repository_id,),
+			)
+			if cursor.fetchone() is None:
+				cursor.execute(
+					"UPDATE watched_repositories SET active = 0 WHERE id = %s",
+					(repository_id,),
+				)
+			db.commit()
+	except Exception as e:
+		db.rollback()
+		logger.exception(f"[FastAPI] Failed to unsubscribe user_id={user_id} to {name}")
+		raise HTTPException(status_code=500) from e
+
+	logger.info(f"[FastAPI] Unsubscribe request successful: {repository.type.value} {name}, user_id={user_id}")
+	return {"status":"ok","detail":"Unsubscribed from repository","name":name}
 
 api.include_router(user_router)
 api.include_router(scheduler_router)

src/models.py

@@ -0,0 +1,52 @@
+import string
+from enum import StrEnum
+
+from pydantic import BaseModel, Field, field_validator
+
+from repository_errors import InvalidOrganisationError, InvalidRepositoryError, InvalidTagError
+
+_REPO_CHARS = frozenset(string.ascii_letters + string.digits + "_.-")
+_MAX_ORG = 39
+_MAX_REPO = 255
+_MAX_TAG = 128
+
+class RepositoryType(StrEnum):
+	GITHUB = "github"
+	DOCKERHUB = "dockerhub"
+
+class RepositoryUpdate(BaseModel):
+	type: RepositoryType
+	org: str = Field(max_length=_MAX_ORG)
+	repo: str = Field(max_length=_MAX_REPO)
+	tag: str = Field(max_length=_MAX_TAG)
+	custom_name: str | None = Field(default=None, max_length=255)
+
+	@field_validator("org")
+	@classmethod
+	def _validate_org(cls, v: str) -> str:
+		v = v.strip()
+		if v and _REPO_CHARS.issuperset(v) and v[0] not in ".-":
+			return v
+		raise InvalidOrganisationError(v)
+
+	@field_validator("repo")
+	@classmethod
+	def _validate_repo(cls, v: str) -> str:
+		v = v.strip()
+		if v and _REPO_CHARS.issuperset(v) and v[0] not in ".-":
+			return v
+		raise InvalidRepositoryError(v)
+
+	@field_validator("tag")
+	@classmethod
+	def _validate_tag(cls, v: str) -> str:
+		v = v.strip()
+		if v and _REPO_CHARS.issuperset(v) and v[0] not in ".-":
+			return v
+		raise InvalidTagError(v)
+
+	@field_validator("custom_name")
+	@classmethod
+	def _blank_name_is_none(cls, v: str | None) -> str | None:
+		return (v or "").strip() or None
+

src/repositories.py

@@ -0,0 +1,123 @@
+from typing import assert_never
+
+from dockerhub_api import (
+	find_package_version_with_tag as find_package_version_with_tag_dockerhub,
+)
+from dockerhub_api import (
+	validate_repository_combination_and_return_latest_tag as validate_repo_dockerhub,
+)
+from github_api import (
+	find_package_version_with_tag as find_package_version_with_tag_github,
+)
+from github_api import (
+	validate_repository_combination_and_return_latest_tag as validate_repo_github,
+)
+from models import RepositoryType, RepositoryUpdate
+from send_notifications import NotificationError, NotificationUnavailableError
+from simple_logger_handler import setup_logger
+
+logger = setup_logger(__name__)
+
+_MAX_MISSING_CHECKS = 4
+
+def fetch_latest(repository_type: RepositoryType, org:str, repo:str, tag:str) -> str:
+	match repository_type:
+		case RepositoryType.GITHUB:
+			return find_package_version_with_tag_github(org, repo, tag)
+		case RepositoryType.DOCKERHUB:
+			return find_package_version_with_tag_dockerhub(org, repo, tag)
+		case _:
+			assert_never(repository_type)
+
+def validate_repository_combination_and_return_latest_tag(repository: RepositoryUpdate) -> str:
+	match repository.type:
+		case RepositoryType.DOCKERHUB:
+			return validate_repo_dockerhub(repository.org, repository.repo, repository.tag)
+		case RepositoryType.GITHUB:
+			return validate_repo_github(repository.org, repository.repo, repository.tag)
+		case _:
+			assert_never(repository.type)
+
+def unsubscribe_every_subscriber_from_repository(
+	db, notifier, repository_id: int, org: str, repo: str, tag: str
+) -> None:
+	"""Count a "not found". On the 4th miss in a row, deactivate the repository and tell its subscribers."""
+	subscribers = []
+	try:
+		with db.cursor() as cursor:
+			cursor.execute(
+				"SELECT missing_checks FROM watched_repositories WHERE id = %s FOR UPDATE",
+				(repository_id,),
+			)
+			row = cursor.fetchone()
+			if row is None:
+				db.rollback()
+				return
+			misses = row[0] + 1
+
+			if misses < _MAX_MISSING_CHECKS:
+				cursor.execute(
+					"UPDATE watched_repositories SET missing_checks = %s WHERE id = %s",
+					(misses, repository_id),
+				)
+			else:
+				cursor.execute(
+					"SELECT user_id, custom_name FROM watched_repositories_subscriptions "
+					"WHERE repository_id = %s AND active = 1",
+					(repository_id,),
+				)
+				subscribers = cursor.fetchall()
+				cursor.execute(
+					"UPDATE watched_repositories_subscriptions SET active = 0 WHERE repository_id = %s",
+					(repository_id,),
+				)
+				cursor.execute(
+					"UPDATE watched_repositories SET active = 0, missing_checks = 0 WHERE id = %s",
+					(repository_id,),
+				)
+		db.commit()
+	except Exception:
+		db.rollback()
+		logger.exception(f"[FastAPI] Failed to record a missing check for repository ID {repository_id}")
+		return
+
+	if misses < _MAX_MISSING_CHECKS:
+		logger.warning(
+			f"[FastAPI] {org}/{repo}:{tag} not found ({misses}/{_MAX_MISSING_CHECKS}), "
+			f"checking again on the next run"
+		)
+		return
+
+	logger.warning(
+		f"[FastAPI] {org}/{repo}:{tag} not found {_MAX_MISSING_CHECKS} times in a row, deactivated "
+		f"repository ID {repository_id} and {len(subscribers)} subscription(s)"
+	)
+
+	for user_id, custom_name in subscribers:
+		try:
+			notifier.send(
+				title=custom_name or f"{org}/{repo}",
+				body=f"{org}/{repo}:{tag} no longer exists, so you were unsubscribed from it",
+				category="utility",
+				user_id=user_id,
+			)
+		except NotificationUnavailableError:
+			logger.warning("[FastAPI] Notifications backend unavailable, not informing the remaining users")
+			break
+		except NotificationError as e:
+			logger.warning(
+				f"[FastAPI] Could not inform user_id={user_id} about the removal "
+				f"status={getattr(e, 'status_code', None)}"
+			)
+
+def reset_missing_checks(db, repository_id: int) -> None:
+	try:
+		with db.cursor() as cursor:
+			cursor.execute(
+				"UPDATE watched_repositories SET missing_checks = 0 WHERE id = %s",
+				(repository_id,),
+			)
+		db.commit()
+	except Exception:
+		db.rollback()
+		logger.exception(f"[FastAPI] Failed to reset the missing counter for repository ID {repository_id}")