I'm runnning `bundle install` Then I get this error:

```
Fetching rdkafka 0.8.1
Installing rdkafka 0.8.1 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

Extracting v1.4.0 into tmp//ports/librdkafka/1.4.0... OK
Running 'configure' for librdkafka 1.4.0... ERROR, review '/Users/codegeek/.rvm/gems/ruby-2.5.1@ls-member/gems/rdkafka-0.8.1/ext/tmp/ports/librdkafka/1.4.0/configure.log' to see what happened. Last lines are:
========================================================================
source: 
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
void foo (void) {
   int s = socket(0, 0, 0);
   close(s);
}

 libpthread () 
    module: self
    action: fail
    reason:
compile check failed:
CC: CC
flags: -lpthread
  -g -O2 -Wall -Wsign-compare -Wfloat-equal -Wpointer-arith -Wcast-align -Wall -Werror _mkltmpVFiBMn.c -o _mkltmpVFiBMn.c.o   -lpthread:
mklove/modules/configure.base: line 1349: -g: command not found
source: #include <pthread.h>

```

But then it will suggest to do:

```
Make sure that `gem install rdkafka -v '0.8.1' --source 'https://rubygems.org/'` succeeds before bundling.

```

So I'll run `gem install rdkafka -v '0.8.1' --source 'https://rubygems.org/'` but then
it will produce an error too

```
Building native extensions. This could take a while...
ERROR:  Error installing rdkafka:
    ERROR: Failed to build gem native extension.

```

Please help. Thanks!