Opt-in Telemetry and Error Reporting

I (github.com/Vexed01) have opt-in telemetry and error reporting built into all of my (github.com/Vexed01/Vex-Cogs) cogs.

Enabling or disabling it affects all of my cogs. You can view whether or not it’s enabled with the [p]vextelemetry command. If this command doesn’t exist, then no data is being sent. This is likely because you haven’t updated yet.

I use a platform called Sentry (sentry.io) to collect this.

No data is collected relating to command usage.

Why collect this?

Error reporting allows me to fix bugs better - with more context to fix them faster and easier. Sentry has a variety of tools to help pinpoint when a bug was introduced.

Performance data is collected mainly because I can’t be everywhere: I want to know if something is quite slow on some machines so I can try and optimise it.

What’s sent?

Where possible, only data associated with my cogs is sent.

Everything that is sent is associated with a temporary session and permanent user UUID. This UUID is random and can’t be linked directly to you or your bot. Anything that is sent includes some context/tags. This is basic information on the setup of the system to help me identify how to reproduce a bug.

For telemetry, the performance of background tasks and loops (for example config migration or time taken to check for updates in my Status cog) is sometimes reported. As stated in the opening of this page, no performance of commands is collected or sent.

For error reporting, whenever something goes wrong with my cogs (this could be a command breaking or something in a background loop) the traceback is sent along with some logs leading up to the error to try and help me work out why it happened. Sentry also sends some variables for debugging. In the future, some related config data (if applicable) might be sent. The IDs in this will be shortened to unidentifiable timestamps, as described below in Sensitive data

Sensitive data

A best effort is made to ensure that no sensitive data is sent. Client-side, all data sent is scrubbed of Discord invite links and Discord IDs are shortened to 4 digits (based on the timestamp of the ID - seconds and milliseconds) - so they can’t be used to identify anything. In the very unlikely event your bot token makes it into the data, this will also be removed. For technical details, see Data scrubbing below. Sentry also has some data scrubbing on their side which should scrub most other sensitive fields. You can see more info on this in their docs.

Data collected is sent to Sentry directly and as such I cannot see your IP address. I will never share any data from Sentry that could be used to identify anyone or stuff that gets past the filters for removing sensitive data.

Technical details of Sentry

Data scrubbing

Data scrubbing has three parts: removal of bot token, removal of Discord invites, and shortening of Discord IDs.

A simple str.replace() is used to replace the bot token with BOT-TOKEN, if it appears for any reason.

For invites, the regex provided in Red’s utils is used and invites replaced with DISCORD-INVITE-LINK

The shortening of Discord IDs is a little more complicated. Docs on these from Discord are here and will help explain this better. In short, the timestamp of the ID is in the ID from bytes 63 to 22. To shorten IDs, this is extracted and the seconds and milliseconds replace the ID. So, if an ID had the timestamp of 2021-08-18 19:23:45.114 the extracted data will be 5114. This part is used because, for all intents and purposes it is random, and that it couldn’t be used (on it’s own) to find the full ID. This means that in the data I see on Sentry, IDs are quite likely to be unique but always the same if they occur in different places. It’s sort of like hashing but worse but easier to implement with regex. This 4 digit ID is prefixed with SHORTENED-ID-

The exact functions can be seen at https://github.com/Vexed01/vex-cog-utils/blob/main/vexcogutils/sentry.py

How Sentry is set up, client-side

Sentry itself suggests a set-up like this:

import sentry_sdk


# roughly copied from https://docs.sentry.io/platforms/python/#configure

However, this would not work if you wanted to report to multiple DSNs - something with is certainly possible if other Cog Creators use Sentry as this would override my initiation or vice versa - or even if core Red starts using Sentry again.

So, I had to go looking for a object-oriented way of using Sentry.

A Hub is created and the Client added to that. This means that the Client only takes in data when explicitly told - useful (for example) to ensure logs from other cog’s aren’t used as breadcrumbs.

This idea was taken from https://github.com/getsentry/sentry-python/issues/610

import sentry_sdk

# roughly copied from SentryHelper (see below)
async def get_sentry_hub(self, dsn: str, cogname: str, cogver: str) -> "Hub":
    hub = sentry_sdk.Hub(

    hub.scope.set_tag("utils_release", ...)
    hub.scope.set_tag("red_release", ...)
    hub.scope.set_user(...)  # see section below called UUIDs

    return hub


# there are now two ways of sending data to Sentry though that Hub:
with hub:
# or:

# for some reason you need to use the "with hub" context manager when
# capturing an exception, otherwise you can just do hub.thing() for everything else


In Vex-Cog-Utils (VCU), as part of the client-side Sentry set up, the SentryHelper class is initiated in the __init__.py to the variable sentryhelper (vexcogutils.sentryhelper).

This class has various things to reduce boilerplate in each cog.

As VCU is designed to work with importlib.reload(), there is also an extra check to not create a new SentryHelper class if the cog is initating from a reload (this is done through checking if sentryhelper is already defined as importlib.reload() keeps global variables).

VexTelemetry (the cog)

The SentryHelper class also adds a cog to the bot called VexTelemetry. This is what has the [p]vextelemetry command to manage whether data is sent or not. This ensures that the cog is always registered, but only once.


Setup data is stored in Red’s config under the fictional cog name Vex-Cog-Utils-Telemetry

Owner notifications

There are two types of messages sent to owners: “master” and “reminder”:

  • The “master” message is the first message to the owner when they first load one of my cogs.

  • A “reminder” message will be sent whenever one of my cogs is loaded for the first time AND a master message was sent previously. If Sentry is enabled, these will be sent every time a new cog of mine is loaded. If Sentry is disabled, these will only be sent once per loading of a new cog of mine IF it is the first cog loaded since last bot restart. This has the added bonus of meaning that when this will be rolled out to all my cogs it will only send 1 DM (or at least that’s the plan…)

To prevent repeated messages, a record of which cogs have been notified is stored in Config (see above)

How Sentry is set up, server-side

All my cogs have their own project and thus DSN. This is so they are separated.

However, they are all in the same organisation/account.

Don’t really thing there’s much else to put here…

Only catching errors for my cogs

I override a function called cog_command_error in my cog classes. This means that all command errors are sent through this if they are part of this cog. To also ensure they are handled normally by Red/dpy, they are sent back to the bot’s error handler with unhandled_by_cog=True.

# In the cog class
async def cog_command_error(self, ctx: "commands.Context", error: "CommandError"):
    await self.bot.on_command_error(ctx, error, unhandled_by_cog=True)  # type:ignore  # Ensure main bot error handler still handles it as normal
    # Sentry logging here

For background loops and tasks, I generally already had full error catching and handling. I just had to send the exception to Sentry as well as log it with Python’s logging module.

Usage of the Vex-Cog-Utils package

When I initially made VCU, it was at the back of my mind that I could one day use this for telemetry and error reporting. As such, all my cogs were already heavily integrated with these utils when I started working on adding Sentry.


I choose to use UUIDs as a way to separate users and allow for features like Release Health to work. This are generated using the standard lib uuid package:

import uuid

uuid.uuid4()  # a completely random UUID