Step 1: Download Libary of RdKafka from below link
https://launchpadlibrarian.net/329894498/librdkafka_0.11.0.orig.tar.gz
then un-tar it
cd linrdkafka-0.11.0
execute the commands
step 2: ./configure –prefix/usr/
Step 3: make
Step 4: make install
Step 5: ldconfig (This is very important step otherwise rdkafka will not execute with PHP)
Step 6: pecl install rdkafka
Step 7: vi /etc/php.ini
add following: extension=rdkafka.so
Step 8: check rdkafka installed properly with PHP
command: php -v
Step 9: If there is not error in step 8 then reload the Apache / Nginx whatever you have.