个人由于没有安装mysql而是装的MariaDB，所以网上说安装mysql,故没有采用，经查阅资料后，详细情况如下：
Gem时报错：
[root@localhost ~]# gem install mysql2 -v '0.3.21'
Building native extensions. This could take a while...
ERROR: Error installing mysql2:
ERROR: Failed to build gem native extension.
current directory: /usr/local/rvm/gems/ruby-2.3.3/gems/mysql2-0.3.21/ext/mysql2
/usr/local/rvm/rubies/ruby-2.3.3/bin/ruby -r ./siteconf20170824-22941-12ykoiq.rb extconf.rb
checking for ruby/thread.h... yes
checking for rb_thread_call_without_gvl() in ruby/thread.h... yes
checking for rb_thread_blocking_region()... no
checking for rb_wait_for_single_fd()... yes
checking for rb_hash_dup()... yes
checking for rb_intern3()... yes
checking for mysql_query() in -lmysqlclient... no
-----
libmysqlclient is missing. Trying again with extra runtime libraries...
-----
checking for main() in -lm... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lz... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lsocket... no
checking for main() in -lnsl... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lmygcc... no
-----
libmysqlclient is missing. You may need to 'apt-get install libmysqlclient-dev' or 'yum install mysql-devel', and try again.
-----
*** 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/local/rvm/rubies/ruby-2.3.3/bin/$(RUBY_BASE_NAME)
--with-mysql-dir
--without-mysql-dir
--with-mysql-include
--without-mysql-include=${mysql-dir}/include
--with-mysql-lib
--without-mysql-lib=${mysql-dir}/lib
--with-mysql-config
--without-mysql-config
--with-mysql-dir
--without-mysql-dir
--with-mysql-include
--without-mysql-include=${mysql-dir}/include
--with-mysql-lib
--without-mysql-lib=${mysql-dir}/lib
--with-mysqlclientlib
--without-mysqlclientlib
--with-mlib
--without-mlib
--with-mysqlclientlib
--without-mysqlclientlib
--with-zlib
--without-zlib
--with-mysqlclientlib
--without-mysqlclientlib
--with-socketlib
--without-socketlib
--with-nsllib
--without-nsllib
--with-mysqlclientlib
--without-mysqlclientlib
--with-mygcclib
--without-mygcclib
To see why this extension failed to compile, please check the mkmf.log which can be found here:
/usr/local/rvm/gems/ruby-2.3.3/extensions/x86_64-linux/2.3.0/mysql2-0.3.21/mkmf.log
extconf failed, exit code 1
Gem files will remain installed in /usr/local/rvm/gems/ruby-2.3.3/gems/mysql2-0.3.21 for inspection.
Results logged to /usr/local/rvm/gems/ruby-2.3.3/extensions/x86_64-linux/2.3.0/mysql2-0.3.21/gem_make.out
[root@localhost admin]# gem install mysql2 -v 0.3.21
Building native extensions. This could take a while...
ERROR: Error installing mysql2:
ERROR: Failed to build gem native extension.
current directory: /usr/local/rvm/gems/ruby-2.3.3/gems/mysql2-0.3.21/ext/mysql2
/usr/local/rvm/rubies/ruby-2.3.3/bin/ruby -r ./siteconf20170824-23131-m5gy52.rb extconf.rb
checking for ruby/thread.h... yes
checking for rb_thread_call_without_gvl() in ruby/thread.h... yes
checking for rb_thread_blocking_region()... no
checking for rb_wait_for_single_fd()... yes
checking for rb_hash_dup()... yes
checking for rb_intern3()... yes
checking for mysql_query() in -lmysqlclient... no
-----
libmysqlclient is missing. Trying again with extra runtime libraries...
-----
checking for main() in -lm... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lz... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lsocket... no
checking for main() in -lnsl... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lmygcc... no
-----
libmysqlclient is missing. You may need to 'apt-get install libmysqlclient-dev' or 'yum install mysql-devel', and try again.
-----
*** 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=${opt-dir}/lib
--with-make-prog
--without-make-prog
--srcdir=.
--curdir
--ruby=/usr/local/rvm/rubies/ruby-2.3.3/bin/$(RUBY_BASE_NAME)
--with-mysql-dir
--without-mysql-dir
--with-mysql-include
--without-mysql-include=${mysql-dir}/include
--with-mysql-lib
--without-mysql-lib=${mysql-dir}/lib
--with-mysql-config
--without-mysql-config
--with-mysql-dir
--without-mysql-dir
--with-mysql-include
--without-mysql-include=${mysql-dir}/include
--with-mysql-lib
--without-mysql-lib=${mysql-dir}/lib
--with-mysqlclientlib
--without-mysqlclientlib
--with-mlib
--without-mlib
--with-mysqlclientlib
--without-mysqlclientlib
--with-zlib
--without-zlib
--with-mysqlclientlib
--without-mysqlclientlib
--with-socketlib
--without-socketlib
--with-nsllib
--without-nsllib
--with-mysqlclientlib
--without-mysqlclientlib
--with-mygcclib
--without-mygcclib
To see why this extension failed to compile, please check the mkmf.log which can be found here:
/usr/local/rvm/gems/ruby-2.3.3/extensions/x86_64-linux/2.3.0/mysql2-0.3.21/mkmf.log
extconf failed, exit code 1
Gem files will remain installed in /usr/local/rvm/gems/ruby-2.3.3/gems/mysql2-0.3.21 for inspection.
Results logged to /usr/local/rvm/gems/ruby-2.3.3/extensions/x86_64-linux/2.3.0/mysql2-0.3.21/gem_make.out
以上是这个错误的内容（有点长），后来有看到论坛大神说是缺少 ’‘mysql-devel“ 的依赖，于是尝试:
[root@localhost ~]# yum install mysql-devel
Loaded plugins: fastestmirror, langpacks
base | 3.6 kB 00:00
epel/x86_64/metalink | 5.2 kB 00:00
epel | 4.3 kB 00:00
extras | 3.4 kB 00:00
updates | 3.4 kB 00:00
Loading mirror speeds from cached hostfile
* base: ftp.sjtu.edu.cn
* epel: mirrors.tuna.tsinghua.edu.cn
* extras: mirrors.tuna.tsinghua.edu.cn
* updates: ftp.sjtu.edu.cn
Resolving Dependencies
--> Running transaction check
---> Package mariadb-devel.x86_64 1:5.5.52-1.el7 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
===============================================================================
Package Arch Version Repository Size
===============================================================================
Installing:
mariadb-devel x86_64 1:5.5.52-1.el7 base 750 k
Transaction Summary
===============================================================================
Install 1 Package
Total download size: 750 k
Installed size: 3.3 M
Is this ok [y/d/N]: y
Downloading packages:
mariadb-devel-5.5.52-1.el7.x86_64.rpm | 750 kB 00:03
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Installing : 1:mariadb-devel-5.5.52-1.el7.x86_64 1/1
Verifying : 1:mariadb-devel-5.5.52-1.el7.x86_64 1/1
Installed:
mariadb-devel.x86_64 1:5.5.52-1.el7
Complete!
[root@localhost admin]# gem install mysql2 -v 0.3.21
Building native extensions. This could take a while...
Successfully installed mysql2-0.3.21
Parsing documentation for mysql2-0.3.21
Installing ri documentation for mysql2-0.3.21
Done installing documentation for mysql2 after 1 seconds
1 gem installed
命令执行的是 mysql-devel,但实际情况安装的 为mariadb-devel
网上大都说，MariaDB 是Mysql 完美替代品，那有没有大神能抽空指点下，mysql-devel 等同于 Mariadb-devel ?还是 MariaDB 真的完美替代与Mysql 了?