Change to handle specifically redis errors

The idea to ignore alerts on fake redis didn't solve the problem completely, because sometimes you'll just develop with a real redis. It also didn't solve the ping we would get on first start up.

After looking into it there seems like there's no actual reason to alert on key errors, as they should only happen if the cache gets wiped for some reason, which shouldn't happen, but in which case we have bigger issues. Alerts are therefore limited to connection errors raised by redis.

This additionally handles only redis errors when writing to it as well. If any other error is raised it is ok for the function to stop at that point, as all variables have already been set. The only thing which doesn't get executed is the confirmation message and logging, the lack of which is an exception message in itself.

1 files changed, 15 insertions, 11 deletions

diff --git a/bot/exts/moderation/defcon.py b/bot/exts/moderation/defcon.py
index aa6dc0790..3d3f0e81e 100644
--- a/bot/exts/moderation/defcon.py
+++ b/bot/exts/moderation/defcon.py
@@ -2,11 +2,11 @@ import asyncio
 import logging
 import traceback
 from collections import namedtuple
-from contextlib import suppress
 from datetime import datetime
 from enum import Enum
 from typing import Optional, Union
 
+from aioredis import RedisError
 from async_rediscache import RedisCache
 from dateutil.relativedelta import relativedelta
 from discord import Colour, Embed, Member, User
@@ -14,7 +14,7 @@ from discord.ext import tasks
 from discord.ext.commands import Cog, Context, group, has_any_role
 
 from bot.bot import Bot
-from bot.constants import Channels, Colours, Emojis, Event, Icons, MODERATION_ROLES, Redis, Roles
+from bot.constants import Channels, Colours, Emojis, Event, Icons, MODERATION_ROLES, Roles
 from bot.converters import DurationDelta, Expiry
 from bot.exts.moderation.modlog import ModLog
 from bot.utils.messages import format_user
@@ -87,13 +87,12 @@ class Defcon(Cog):
             settings = await self.defcon_settings.to_dict()
             self.threshold = parse_duration_string(settings["threshold"]) if settings["threshold"] else None
             self.expiry = datetime.fromisoformat(settings["expiry"]) if settings["expiry"] else None
-        except Exception:
+        except RedisError:
             log.exception("Unable to get DEFCON settings!")
-            if not Redis.use_fakeredis:
-                await self.channel.send(
-                    f"<@&{Roles.moderators}> <@&{Roles.devops}> **WARNING**: Unable to get DEFCON settings!"
-                    f"\n\n```{traceback.format_exc()}```"
-                )
+            await self.channel.send(
+                f"<@&{Roles.moderators}> <@&{Roles.devops}> **WARNING**: Unable to get DEFCON settings!"
+                f"\n\n```{traceback.format_exc()}```"
+            )
 
         else:
             if self.expiry:
@@ -210,14 +209,19 @@ class Defcon(Cog):
         if self.expiry is not None:
             self.scheduler.schedule_at(expiry, 0, self._remove_threshold())
 
-        with suppress(Exception):
+        self._update_notifier()
+
+        # Make sure to handle the critical part of the update before writing to Redis.
+        error = ""
+        try:
             await self.defcon_settings.update(
                 {
                     'threshold': Defcon._stringify_relativedelta(self.threshold) if self.threshold else "",
                     'expiry': expiry.isoformat() if expiry else 0
                 }
             )
-        self._update_notifier()
+        except RedisError:
+            error = ", but failed to write to cache"
 
         action = Action.DURATION_UPDATE
 
@@ -234,7 +238,7 @@ class Defcon(Cog):
             channel_message = "removed"
 
         await self.channel.send(
-            f"{action.value.emoji} DEFCON threshold {channel_message}."
+            f"{action.value.emoji} DEFCON threshold {channel_message}{error}."
         )
         await self._send_defcon_log(action, author)
         self._update_channel_topic()