# hackweek-feature-flags

**Repository Path**: mirrors_getsentry/hackweek-feature-flags

## Basic Information

- **Project Name**: hackweek-feature-flags
- **Description**: You got features? We got flags!
- **Primary Language**: Unknown
- **License**: Not specified
- **Default Branch**: main
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2022-08-27
- **Last Updated**: 2026-02-22

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# Hackweek: Feature Flags

You got features? We got flags!

This hackweek project implements client side feature flags for
Sentry.  It's supported in the Python and Dart SDK on branches.

```python
import sentry_sdk

sentry_sdk.init(
    environment="prod",
    _experiments={"feature_flags_enabled": True},
)

# this blocks until flags are fetched
sentry_sdk.wait_until_ready()

# Checks a feature flag if it's enabled
if sentry_sdk.is_feature_flag_enabled("myFeatureFlag"):
    print("Feature flag enabled!")
```

# UI

<img src="https://github.com/getsentry/hackweek-feature-flags/blob/main/screenshots/overview.png?raw=true" width="100%" alt="screenshot">

# How does it work?

There is a Sentry UI where basic rules can be defined for feature flags.
Multiple feature flags can be defined with multiple segments within each
flag to control how they are rolled out.  Each segment is matched against
the provided tags and the first segment that matches defines the result.

Feature flags can be numeric, boolean or string types and additionally
they can carry arbitrary JSON payloads.

Additionally special internal feature flags are used and directly
influence the SDK.  This way the sample rate for erros and transactions
can be remotely reconfigured.  The same is also true for the experimental
profiling on the Python SDK.

Feature flags that are active are pushed out via Relay to client SDKs and
evaluated there.

Feature flags are sticky by user or device and multiple feature flags can
be grouped together to ensure that they are rolled out together if wanted.

The detailed protocol specs [can be found here](Protocol.md).

# Draft PRs

* [Dart SDK](https://github.com/getsentry/sentry-dart/pull/984)
* [Python SDK](https://github.com/getsentry/sentry-python/pull/1581)
* [Relay](https://github.com/getsentry/relay/pull/1433)
* [Sentry](https://github.com/getsentry/sentry/pull/38086)

# Nice-to-have Features

These are some things we might add in the future:

* Force random stickiness (disabled by default), useful for non-user-facing features
* Date and Time expiration, enable HTTP payload for errors directly from the Issues page for only 1h
* Built-in feature flag to SDKs to enable verbose reporting (attachments for full outgoing HTTP requests and their responses)
* Basic reusable segments (list of VIP orgs) that can be referenced.

# SDK Documentation

Here are the basic docs for this feature:

## Flag Checking

The most basic check involves boolean feature flags.  For these a convenient
method `isFeatureFlagEnabled` is provided:

```python
if sentry_sdk.is_feature_flag_enabled("featureFlagName"):
    # do somethign
```

By default the tags, transaction, environment and release are passed to the feature
flag evaluator.  Additionally custom values can be provided as well:

```python
if sentry_sdk.is_feature_flag_enabled("featureFlagName", context={"key": "value"}):
    # do somethign
```

If a feature flag is unknown or no rule matched, the return value is `null` which is
typically seen as false.

## Flag Result Access

For more complex cases the result value can be directly accessed.  The return value is
either `null` if the flag is not known or a feature flag info object with `result`
and `payload`:

```python
sample_rate = 1.0
info = sentry_sdk.get_feature_flag_info("myOwnSampleRate")
if info:
    sample_rate = info.result
```

Additionally extra payload can be set which allows you to reconfigure things:

```python
info = sentry_sdk.get_feature_flag_info("showWelcomeBanner")
if info is not None:
    show_banner(info.payload["banner_url"], info.payload["duration"])
```