LaunchDarkly SDK for Go

Important note

As mentioned in the repository changelog, the go-client project has been renamed to go-server-sdk. All future releases will be made from the new repository. Please consider updating your import paths and filing potential requests in that repository's issue tracker.

Go runtime compatibility

This version of the LaunchDarkly SDK has been tested with Go 1.8 through 1.10.

Quick setup

1. Install the SDK with the go tool:

go get gopkg.in/launchdarkly/go-client.v4

2. Import the LaunchDarkly client:

import ld "gopkg.in/launchdarkly/go-client.v4"

3. Create a new LDClient with your SDK key:

ldClient, err := ld.MakeClient("YOUR_SDK_KEY", 5*time.Second)
if err != nil {
    log.Fatalf("Error creating launch darkly client: %s", err)
}
defer ldClient.Close()

If you are reusing a global instance you probably want to not defer ldClient.Close() but instead close it when the application exits.

HTTPS proxy

Go's standard HTTP library provides built-in support for the use of an HTTPS proxy. If the HTTPS_PROXY 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

Your first feature flag

1. Create a new feature flag on your dashboard
2. In your application code, use the feature's key to check whether the flag is on for each user:

key := "user@test.com"
showFeature, _ := ldClient.BoolVariation("your.flag.key", ld.User{Key: &key}, false)
if showFeature {
    // application code to show the feature
} else {
    // the code to run if the feature is off
}

Database integrations

Feature flag data can be kept in a persistent store using Redis, Consul, or DynamoDB. These adapters are implemented in the subpackages redis, ldconsul, and lddynamodb; to use them, call the New...FeatureStore function provided by the subpackage, and put the returned object in the FeatureStore field of your client configuration. See the subpackages and the SDK reference guide for more information.

Using flag data from a file

For testing purposes, the SDK can be made to read feature flag state from a file or files instead of connecting to LaunchDarkly. See ldfiledata and ldfilewatch for more details.

Learn more

Check out our documentation for in-depth instructions on configuring and using LaunchDarkly. You can also head straight to the complete reference guide for this SDK and the API reference.

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. We've also published an SDK contributor's guide that provides a detailed explanation of how our SDKs work.

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 for a complete list.
• Explore LaunchDarkly
  • launchdarkly.com for more information
  • docs.launchdarkly.com for our documentation and SDK reference guides
  • apidocs.launchdarkly.com for our API documentation
  • blog.launchdarkly.com for the latest product updates
  • Feature Flagging Guide for best practices and strategies