我们在进行fluentd，elasticsearch，kibana环境搭建时，fluentd需要es作为存储的平台，这个时候在配置 vi /etc/td-agent/td-agent.conf时
  1. <match task.**>
  2. host 192.168.0.1 ##### elasticsearch 服务器地址
  3. type elasticsearch
  4. logstash_format true
  5. flush_interval 5s
  6. include_tag_key true
  7. tag_key mapred
  8. </match>


中间涉及到使用elasticsearch，所以我们要安装 

fluent-plugin-elasticsearch

/usr/lib64/fluent/ruby/bin/fluent-gem install fluent-plugin-elasticsearch
 
 
发生错误：ERROR:  Error installing fluent-plugin-elasticsearch:
    ERROR: Failed to build gem native extension.

        /usr/lib64/fluent/ruby/bin/ruby extconf.rb
checking for curl-config... no
checking for main() in -lcurl... no
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
    --with-opt-dir
    --without-opt-dir
    --with-opt-include
    --without-opt-include=${opt-dir}/include
    --with-opt-lib
    --without-opt-lib=${opt-dir}/lib
    --with-make-prog
    --without-make-prog
    --srcdir=.
    --curdir
    --ruby=/usr/lib64/fluent/ruby/bin/ruby
    --with-curl-dir
    --without-curl-dir
    --with-curl-include
    --without-curl-include=${curl-dir}/include
    --with-curl-lib
    --without-curl-lib=${curl-dir}/lib
    --with-curllib
    --without-curllib
extconf.rb:39:in `<main>':   Can't find libcurl or curl/curl.h (RuntimeError)
 
 
这个是由于我们没有安装 libcurl-devel造成的，我们只要先yum install  libcurl-devel，再次重新/usr/lib64/fluent/ruby/bin/fluent-gem install fluent-plugin-elasticsearch时就可以顺利进行下去。如此，fluentd配置成功，可以启动了service td-agent start