# LaunchDarkly Server-side SDK for Go

[![Circle CI](https://circleci.com/gh/launchdarkly/go-server-sdk.svg?style=shield)](https://circleci.com/gh/launchdarkly/go-server-sdk) [![Documentation](https://img.shields.io/static/v1?label=go.dev&message=reference&color=00add8)](https://pkg.go.dev/github.com/launchdarkly/go-server-sdk/v6)

## LaunchDarkly overview

[LaunchDarkly](https://www.launchdarkly.com) is a feature management platform that serves over 100 billion feature flags daily to help teams build better software, faster. [Get started](https://docs.launchdarkly.com/docs/getting-started) using LaunchDarkly today!

## Supported Go versions

This version of the LaunchDarkly SDK requires a Go version of 1.18 or higher.

## Getting started

Refer to the [SDK documentation](https://docs.launchdarkly.com/sdk/server-side/go#getting-started) for instructions on getting started with using the SDK.

## HTTPS proxy

There are two ways to specify the use of a proxy server. First, you can do it programmatically: see ldcomponents.HTTPConfiguration().

Second, Go's standard HTTP library also provides built-in support for the use of an HTTPS proxy via the `HTTPS_PROXY` environment variable. If this environment variable is present, then the SDK will proxy all network requests through the URL provided.

How to set the HTTPS_PROXY environment variable on Mac/Linux systems:
```
export HTTPS_PROXY=https://web-proxy.domain.com:8080
```

How to set the HTTPS_PROXY environment variable on Windows systems:
```
set HTTPS_PROXY=https://web-proxy.domain.com:8080
```

If your proxy requires authentication then you can prefix the URN with your login information:
```
export HTTPS_PROXY=http://user:pass@web-proxy.domain.com:8080
```
or
```
set HTTPS_PROXY=http://user:pass@web-proxy.domain.com:8080
```

## Database integrations

Feature flag data can be kept in a persistent store using a database integration; LaunchDarkly provides integrations for several databases, such as Redis, which are provided in separate packages. See the [SDK reference guide](https://docs.launchdarkly.com/sdk/concepts/data-stores) for more information.

## Integration with easyjson

The SDK frequently reads and writes JSON data when it communicates with LaunchDarkly services or uses a persistent data store. By default, it uses LaunchDarkly's open-source JSON library [`go-jsonstream`](https://github.com/launchdarkly/go-jsonstream), which is considerably faster than Go's built-in `encoding/json` and does not depend on any third-party code. However, the SDK can optionally integrate with the third-party library [`easyjson`](https://github.com/mailru/easyjson), which may be even faster in some cases, without requiring any changes in your code. To enable this, set the build tag `launchdarkly_easyjson` when you run `go build`. The `easyjson` library is still under development and has some potential compatibility issues; see its documentation for more details.

If you do not set the `launchdarkly_easyjson` build tag, the SDK does not use any code from `easyjson`.

## Learn more

Check out our [documentation](http://docs.launchdarkly.com) for in-depth instructions on configuring and using LaunchDarkly. You can also head straight to the [complete reference guide for this SDK](http://docs.launchdarkly.com/docs/go-sdk-reference) or our [code-generated API documentation](https://pkg.go.dev/github.com/launchdarkly/go-server-sdk/v6).

## Testing

We run integration tests for all our SDKs using a centralized test harness. This approach gives us the ability to test for consistency across SDKs, as well as test networking behavior in a long-running application. These tests cover each method in the SDK, and verify that event sending, flag evaluation, stream reconnection, and other aspects of the SDK all behave correctly.

## Contributing

We encourage pull requests and other contributions from the community. Check out our [contributing guidelines](CONTRIBUTING.md) for instructions on how to contribute to this SDK.

## About LaunchDarkly

* LaunchDarkly is a continuous delivery platform that provides feature flags as a service and allows developers to iterate quickly and safely. We allow you to easily flag your features and manage them from the LaunchDarkly dashboard.  With LaunchDarkly, you can:
    * Roll out a new feature to a subset of your users (like a group of users who opt-in to a beta tester group), gathering feedback and bug reports from real-world use cases.
    * Gradually roll out a feature to an increasing percentage of users, and track the effect that the feature has on key metrics (for instance, how likely is a user to complete a purchase if they have feature A versus feature B?).
    * Turn off a feature that you realize is causing performance problems in production, without needing to re-deploy, or even restart the application with a changed configuration file.
    * Grant access to certain features based on user attributes, like payment plan (eg: users on the ‘gold’ plan get access to more features than users in the ‘silver’ plan). Disable parts of your application to facilitate maintenance, without taking everything offline.
* LaunchDarkly provides feature flag SDKs for a wide variety of languages and technologies. Check out [our documentation](https://docs.launchdarkly.com/sdk) for a complete list.
* Explore LaunchDarkly
    * [launchdarkly.com](https://www.launchdarkly.com/ "LaunchDarkly Main Website") for more information
    * [docs.launchdarkly.com](https://docs.launchdarkly.com/  "LaunchDarkly Documentation") for our documentation and SDK reference guides
    * [apidocs.launchdarkly.com](https://apidocs.launchdarkly.com/  "LaunchDarkly API Documentation") for our API documentation
    * [blog.launchdarkly.com](https://blog.launchdarkly.com/  "LaunchDarkly Blog Documentation") for the latest product updates