LaunchDarkly Server-Side SDK for C/C++

The LaunchDarkly Server-Side SDK for C/C++ is designed primarily for use in multi-user systems such as web servers and applications. It follows the server-side LaunchDarkly model for multi-user contexts. It is not intended for use in desktop and embedded systems applications.

For using LaunchDarkly in client-side C/C++ applications, refer to our client-side C/C++ SDK.

LaunchDarkly overview

LaunchDarkly is a feature management platform that serves over 100 billion feature flags daily to help teams build better software, faster. Get started using LaunchDarkly today!

Compatibility

This version of the LaunchDarkly SDK is compatible with POSIX environments (Linux, OS X, BSD) and Windows.

Getting started

Download a release archive from the GitHub Releases for use in your project. Refer to the SDK documentation for complete instructions on getting started with using the SDK.

CMake Compatibility

Component	Minimum CMake version required
SDK	3.11
Contract Tests	3.14

CMake Usage

CMake is a highly flexible build-system generator. The SDK strives to support two common use-cases for integrating a CMake-based project into a main application.

Adding the SDK as a sub-project with add_subdirectory()

First, obtain the SDK's source code and place the directory somewhere within your project. For example:

cd your-project
git clone https://github.com/launchdarkly/c-server-sdk.git

Add the source directory within your project's CMakeLists.txt:

add_subdirectory(c-server-sdk)

The SDK's ldserverapi::ldserverapi target should be available for linking. For example:

target_link_libraries(yourproject ldserverapi::ldserverapi)

Installing & finding the SDK with find_package()

Instead of including the SDK's project directly in another project, the SDK can instead be installed to a location on the build machine.

The installed files can be referenced by another CMake project. For example:

git clone https://github.com/launchdarkly/c-server-sdk.git
cd c-server-sdk

# If no install prefix is provided, standard GNU install directories are used.
cmake .. -DCMAKE_INSTALL_PREFIX=/path/where/sdk/should/be/installed
cmake --build . --target install

In your project's CMakeLists.txt:

# Replace with latest version
find_package(ldserverapi 2.7.1 REQUIRED)

target_link_libraries(yourproject ldserverapi::ldserverapi)

Dependencies

Component	Package Name	Location	Method	Minimum Version	Patched
SDK	PCRE	Build host	FindPCRE		N
SDK	CURL	Build host	FindCURL		N
SDK	pepaslabs/hexify	Github	FetchContent	Pegged @ f823b	Y
SDK	h2non/semver	Github	FetchContent	Pegged @ bd1db	Y
SDK	clibs/sha1	Github	FetchContent	Pegged @ fa1d9	N
SDK	chansen/timestamp	Github	FetchContent	Pegged @ b205c	Y
SDK	troydhanson/uthash	Github	FetchContent	v2.3.0	N
SDK	NetBSD strptime.c	Vendored	N/A	N/A	Unknown
SDK with Redis	hiredis	Build host	FindHiredis		N
Contract Tests	yhirose/cpp-httplib	Github	FetchContent	v0.10.2	N
Contract Tests	nlohmann/json	Github	FetchContent	v3.10.5	N

Unit tests

The project uses C++ for unit testing. To exclude the unit tests from the SDK build, disable via CMake option:

cmake .. -DBUILD_TESTING=OFF <other options...>

Redis store integration

To enable the Redis store integration, the hiredis package must be present on the build host. Enable support via cmake option:

cmake .. -DREDIS_STORE=ON <other options...>

The SDK library artifacts will now contain Redis support, and an additional header will be made available in the build/install trees.

Learn more

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

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 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. Read 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