rdkafka-sys

Low level bindings to librdkafka, a C library for the [Apache Kafka] protocol with producer, consumer, and admin clients.

For a safe wrapper, see the [rdkafka] crate.

Version

The rdkafka-sys version number is in the format X.Y.Z+RX.RY.RZ, where X.Y.Z is the version of this crate and follows SemVer conventions, while RX.RY.RZ is the version of the bundled librdkafka.

Note that versions before v2.0.0+1.4.2 did not follow this convention, and instead directly correspond to the bundled librdkafka version.

Build

Known issues

• When any of librdkafka's optional dependencies are enabled, like libz or OpenSSL, if you have multiple versions of that library installed upon your system, librdkafka's build system may disagree with Cargo about which version of the library to use! This can result in subtly broken builds, if librdkafka compiles against the headers for one version but Cargo links against a different version. For complete confidence when building release binaries, use an environment like a Docker container or a chroot jail where you can guarantee that only one version of each dependency is present. The current design of Cargo unfortunately makes this nearly impossible to fix.

Features

By default a submodule with the librdkafka sources will be used to compile and statically link the library.

The dynamic-linking feature can be used to link rdkafka to a locally installed version of librdkafka: if the feature is enabled, the build script will use pkg-config to check the version of the library installed in the system, and it will configure the compiler to dynamically link against it. The system version of librdkafka must exactly match the version of librdkafka bundled with this crate.

The cmake-build feature builds librdkafka with its [CMake] build system, rather than its default [mklove]-based build system. This feature requires that CMake is installed on the build machine.

The following features directly correspond to librdkafka features (i.e., flags you would pass to configure if you were compiling manually).

• The ssl feature enables SSL support. By default, the system's OpenSSL library is dynamically linked, but static linking of the version bundled with the [openssl-sys] crate can be requested with the ssl-vendored feature.
• The gssapi feature enables SASL GSSAPI support with Cyrus libsasl2. By default the system's libsasl2 is dynamically linked, but static linking of the version bundled with the [sasl2-sys] crate can be requested with the gssapi-vendored feature.
• The libz feature enables support for zlib compression. This feature is enabled by default. By default, the system's libz is dynamically linked, but static linking of the version bundled with the [libz-sys] crate can be requested with the libz-static feature.
• The zstd feature enables support for ZSTD compression. By default, this builds and statically links the version bundled with the [zstd-sys] crate, but dynamic linking of the system's version can be requested with the zstd-pkg-config feature.
• The external-lz4 feature statically links against the copy of liblz4 bundled with the [lz4-sys] crate. By default, librdkafka statically links against its own bundled version of liblz4. Due to limitations with lz4-sys, it is not yet possible to dynamically link against the system's version of liblz4.

All features are disabled by default unless noted otherwise above. The build process is defined in [build.rs].