I don't understand how you find out this version compatibility from this output.
I installed json 1.8.6 and I'm still facing error with msgpack like below.
I tried installing msgpack latest version but it didn't work.
On an another host I tried installing via td-agent and it says Fluentd is not present al though I installed it.
Please see below.
Td-agengt
>
> [sarnagar@tdagserver sbin]$ sudo td-agent-gem install /home/sarnagar/fluentd-0.14.16.gem
>
> Successfully installed fluentd-0.14.16
>
> Parsing documentation for fluentd-0.14.16
>
> Done installing documentation for fluentd after 4 seconds
>
> 1 gem installed
>
> [sarnagar@tdagserver sbin]$ sudo td-agent-gem install /home/sarnagar/fluent-plugin-splunk-ex-1.0.2.gem
>
> ERROR: Could not find a valid gem 'fluentd' (~> 0.10.17) in any repository
>
> [sarnagar@tdagserver sbin]$
>
>
>
2. Fluentd agent
>
>
>
> [root@fluagserver fluentd1]# gem install fluent-plugin-splunk-ex --source
http://rubygems.org
>
> Fetching: msgpack-0.5.12.gem (100%)
>
> Building native extensions. This could take a while...
>
> ERROR: Error installing fluent-plugin-splunk-ex:
>
> ERROR: Failed to build gem native extension.
>
>
>
> current directory: /usr/local/rvm/gems/ruby-2.4.0/gems/msgpack-0.5.12/ext/msgpack
>
> /usr/local/rvm/rubies/ruby-2.4.0/bin/ruby -r ./siteconf20170525-29932-zqpccp.rb extconf.rb
>
> checking for ruby/st.h... yes
>
> checking for st.h... yes
>
> checking for rb_str_replace() in ruby.h... yes
>
> checking for rb_intern_str() in ruby.h... yes
>
> checking for rb_sym2str() in ruby.h... yes
>
> checking for rb_str_intern() in ruby.h... yes
>
> creating Makefile
>
>
>
> current directory: /usr/local/rvm/gems/ruby-2.4.0/gems/msgpack-0.5.12/ext/msgpack
>
> make "DESTDIR=" clean
>
>
>
> current directory: /usr/local/rvm/gems/ruby-2.4.0/gems/msgpack-0.5.12/ext/msgpack
>
> make "DESTDIR="
>
> compiling buffer.c
>
> compiling buffer_class.c
>
> compiling core_ext.c
>
> core_ext.c: In function ‘MessagePack_core_ext_module_init’:
>
> core_ext.c:121: error: ‘rb_cFixnum’ undeclared (first use in this function)
>
> core_ext.c:121: error: (Each undeclared identifier is reported only once
>
> core_ext.c:121: error: for each function it appears in.)
>
> core_ext.c:122: error: ‘rb_cBignum’ undeclared (first use in this function)
>
> At top level:
>
> cc1: warning: unrecognized command line option "-Wno-self-assign"
>
> cc1: warning: unrecognized command line option "-Wno-constant-logical-operand"
>
> cc1: warning: unrecognized command line option "-Wno-parentheses-equality"
>
> cc1: warning: unrecognized command line option "-Wno-tautological-compare"
>
> make: *** [core_ext.o] Error 1
>
>
>
> make failed, exit code 2
>
>
>
> Gem files will remain installed in /usr/local/rvm/gems/ruby-2.4.0/gems/msgpack-0.5.12 for inspection.
>
> Results logged to /usr/local/rvm/gems/ruby-2.4.0/extensions/x86_64-linux/2.4.0/msgpack-0.5.12/gem_make.out
>
> [root@fluagserver fluentd1]# tail -f /usr/local/rvm/gems/ruby-2.4.0/extensions/x86_64-linux/2.4.0/msgpack-0.5.12/gem_make.out
>
> core_ext.c:121: error: for each function it appears in.)
>
> core_ext.c:122: error: ‘rb_cBignum’ undeclared (first use in this function)
>
> At top level:
>
> cc1: warning: unrecognized command line option "-Wno-self-assign"
>
> cc1: warning: unrecognized command line option "-Wno-constant-logical-operand"
>
> cc1: warning: unrecognized command line option "-Wno-parentheses-equality"
>
> cc1: warning: unrecognized command line option "-Wno-tautological-compare"
>
> make: *** [core_ext.o] Error 1