From 47aee73574629deeb7ae3824cca9966eee8fa608 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rn-Michael=20Miehe?=
 <40151420+ldericher@users.noreply.github.com>
Date: Wed, 7 Sep 2022 00:23:31 +0000
Subject: [PATCH] perform checks before running the API

---
 api/ovdashboard_api/dav_common.py | 50 +++++++++++++++++++++++++++++++
 api/ovdashboard_api/main.py       | 14 +++++----
 api/ovdashboard_api/settings.py   |  8 +++--
 3 files changed, 63 insertions(+), 9 deletions(-)

diff --git a/api/ovdashboard_api/dav_common.py b/api/ovdashboard_api/dav_common.py
index 473ee19..808882f 100644
--- a/api/ovdashboard_api/dav_common.py
+++ b/api/ovdashboard_api/dav_common.py
@@ -3,6 +3,8 @@ Definition of WebDAV and CalDAV clients.
 """
 
 from functools import lru_cache
+from logging import getLogger
+from time import sleep
 from typing import Any, Iterator
 
 from caldav import DAVClient as CalDAVclient
@@ -19,6 +21,54 @@ _WEBDAV_CLIENT = WebDAVclient({
     "webdav_password": SETTINGS.webdav.password,
 })
 
+_logger = getLogger(__name__)
+
+
+def webdav_check() -> bool:
+    """
+    Checks if base resources are available.
+    """
+
+    _logger.info(
+        "Production mode is %s.",
+        "enabled" if SETTINGS.production_mode else "disabled",
+    )
+
+    if SETTINGS.production_mode:
+        for _ in range(SETTINGS.webdav_retries):
+            if _WEBDAV_CLIENT.check(""):
+                break
+
+            _logger.warning(
+                "Waiting for WebDAV connection to %s ...",
+                repr(SETTINGS.webdav.url),
+            )
+            sleep(30)
+
+        _logger.debug("WebDAV connection OK!")
+
+    elif _WEBDAV_CLIENT.check(""):
+        _logger.debug("WebDAV connection OK!")
+
+    else:
+        _logger.error(
+            "WebDAV connection to %s FAILED!",
+            repr(SETTINGS.webdav.url),
+        )
+        return False
+
+    if _WEBDAV_CLIENT.check(SETTINGS.webdav_prefix):
+        _logger.debug("WebDAV prefix directory FOUND!")
+
+    else:
+        _logger.error(
+            "WebDAV prefix directory %s NOT FOUND, please create it!",
+            repr(SETTINGS.webdav_prefix),
+        )
+        return False
+
+    return True
+
 
 @lru_cache(maxsize=SETTINGS.cache_size)
 def webdav_resource(remote_path: Any) -> WebDAVResource:
diff --git a/api/ovdashboard_api/main.py b/api/ovdashboard_api/main.py
index be43aa7..67a0c51 100644
--- a/api/ovdashboard_api/main.py
+++ b/api/ovdashboard_api/main.py
@@ -9,6 +9,7 @@ Creates the main `FastAPI` app.
 import uvicorn
 from fastapi import FastAPI
 
+from .dav_common import webdav_check
 from .routers import main_router
 from .settings import SETTINGS
 
@@ -36,12 +37,13 @@ def main() -> None:
     If the `main` script is run, `uvicorn` is used to run the app.
     """
 
-    uvicorn.run(
-        app="ovdashboard_api.main:app",
-        host="0.0.0.0",
-        port=8000,
-        reload=not SETTINGS.production_mode,
-    )
+    if webdav_check():
+        uvicorn.run(
+            app="ovdashboard_api.main:app",
+            host="0.0.0.0",
+            port=8000,
+            reload=not SETTINGS.production_mode,
+        )
 
 
 if __name__ == "__main__":
diff --git a/api/ovdashboard_api/settings.py b/api/ovdashboard_api/settings.py
index 1877c14..92e20d8 100644
--- a/api/ovdashboard_api/settings.py
+++ b/api/ovdashboard_api/settings.py
@@ -49,18 +49,20 @@ class Settings(BaseSettings):
 
     production_mode: bool = False
     log_level: str = "DEBUG"
+    cache_seconds: int = 30
+    cache_size: int = 30
+
     api_v1_prefix: str = "api/v1"
     openapi_url: str = "/openapi.json"
     docs_url: Optional[str] = "/docs"
     redoc_url: Optional[str] = "/redoc"
 
     webdav: DavSettings = DavSettings()
+    webdav_retries: int = 20
     webdav_prefix: str = "/ovdashboard"
     config_path: str = "config.txt"
-    caldav: DavSettings = DavSettings()
 
-    cache_seconds: int = 30
-    cache_size: int = 30
+    caldav: DavSettings = DavSettings()
 
     class Config:
         env_nested_delimiter = "__"