build: use the system provided librdkafka if found

e.g. buildroot has logic to build librdkafka,
so if pkg_check_modules can find a suitable version,
then use that one if -DFLB_PREFER_SYSTEM_LIB_KAFKA=Yes.

Signed-off-by: Thomas Devoogdt <[email protected]>

Author: ThomasDevoogdt

CMakeLists.txt

@@ -206,6 +206,7 @@ option(FLB_PREFER_SYSTEM_LIBS             "Prefer system libraries"
 option(FLB_PREFER_SYSTEM_LIB_BACKTRACE    "Prefer the libbacktrace system library"    ${FLB_PREFER_SYSTEM_LIBS})
 option(FLB_PREFER_SYSTEM_LIB_CARES        "Prefer the libcares system library"        ${FLB_PREFER_SYSTEM_LIBS})
 option(FLB_PREFER_SYSTEM_LIB_JEMALLOC     "Prefer the libjemalloc system library"     ${FLB_PREFER_SYSTEM_LIBS})
+option(FLB_PREFER_SYSTEM_LIB_KAFKA        "Prefer the libkafka system library"        ${FLB_PREFER_SYSTEM_LIBS})
 option(FLB_PREFER_SYSTEM_LIB_LUAJIT       "Prefer the libluajit system library"       ${FLB_PREFER_SYSTEM_LIBS})
 option(FLB_PREFER_SYSTEM_LIB_NGHTTP2      "Prefer the libnghttp2 system library"      ${FLB_PREFER_SYSTEM_LIBS})
 
@@ -992,17 +993,16 @@ if(FLB_BACKTRACE)
 endif()
 
 if(FLB_IN_KAFKA OR FLB_OUT_KAFKA)
-    FLB_OPTION(RDKAFKA_BUILD_STATIC    On)
-    FLB_OPTION(RDKAFKA_BUILD_EXAMPLES Off)
-    FLB_OPTION(RDKAFKA_BUILD_TESTS    Off)
-    FLB_OPTION(ENABLE_LZ4_EXT         Off)
-
-    # disable Curl
-    if (FLB_SYSTEM_MACOS)
-      FLB_OPTION(WITH_CURL  Off)
-    endif()
-
-    add_subdirectory(${FLB_PATH_LIB_RDKAFKA} EXCLUDE_FROM_ALL)
+  if(FLB_PREFER_SYSTEM_LIB_KAFKA)
+    find_package(PkgConfig)
+    pkg_check_modules(KAFKA rdkafka>=2.3.0)
+  endif()
+  if(KAFKA_FOUND)
+    include_directories(${KAFKA_INCLUDE_DIRS})
+    link_directories(${KAFKA_LIBRARY_DIRS})
+  else()
+    include(cmake/kafka.cmake)
+  endif()
 endif()
 
 # Onigmo (Regex Engine) options

cmake/headers.cmake

@@ -42,10 +42,6 @@ include_directories(
   ${CMAKE_CURRENT_BINARY_DIR}/lib/monkey/include/monkey/
   )
 
-if(FLB_IN_KAFKA OR FLB_OUT_KAFKA)
-    include_directories(${FLB_PATH_ROOT_SOURCE}/${FLB_PATH_LIB_RDKAFKA}/src/)
-endif()
-
 if(FLB_UTF8_ENCODER)
   include_directories(${FLB_PATH_ROOT_SOURCE}/${FLB_PATH_LIB_TUTF8E}/include)
 endif()

cmake/kafka.cmake

@@ -0,0 +1,16 @@
+# kafka cmake
+FLB_OPTION(RDKAFKA_BUILD_STATIC    On)
+FLB_OPTION(RDKAFKA_BUILD_EXAMPLES Off)
+FLB_OPTION(RDKAFKA_BUILD_TESTS    Off)
+FLB_OPTION(ENABLE_LZ4_EXT         Off)
+
+# disable Curl
+if (FLB_SYSTEM_MACOS)
+  FLB_OPTION(WITH_CURL  Off)
+endif()
+
+include_directories(${FLB_PATH_ROOT_SOURCE}/${FLB_PATH_LIB_RDKAFKA}/src/)
+
+add_subdirectory(${FLB_PATH_LIB_RDKAFKA} EXCLUDE_FROM_ALL)
+
+set(KAFKA_LIBRARIES "rdkafka")

plugins/in_kafka/CMakeLists.txt

@@ -2,5 +2,6 @@ set(src
   in_kafka.c
   )
 
-FLB_PLUGIN(in_kafka "${src}" "rdkafka")
+FLB_PLUGIN(in_kafka "${src}" ${KAFKA_LIBRARIES})
+target_include_directories(flb-plugin-in_kafka PUBLIC ${KAFKA_INCLUDEDIR}/librdkafka)
 target_link_libraries(flb-plugin-in_kafka -lpthread)

plugins/out_kafka/CMakeLists.txt

@@ -4,5 +4,6 @@ set(src
   kafka_topic.c
   kafka.c)
 
-FLB_PLUGIN(out_kafka "${src}" "rdkafka")
+FLB_PLUGIN(out_kafka "${src}" ${KAFKA_LIBRARIES})
+target_include_directories(flb-plugin-out_kafka PUBLIC ${KAFKA_INCLUDEDIR}/librdkafka)
 target_link_libraries(flb-plugin-out_kafka -lpthread)