解决方法：配置群集时# gem install redis 报错：Unable to require openssl, install OpenSSL and rebuild ruby

问题：
前面已经在/usr/local/src安装了ruby-2.3.0.tar.gz、rubygems-2.4.2.tar.gz。
在配置 redis-3.1.1 群集中，使用gem install 安装 ruby redis 接口时报：

# [root@localhost src]# gem install redis --version 3.0.0
# # 由于源的原因，可能下载失败，就手动下载下来安装
[root@localhost src]# gem install /usr/local/src/redis-3.2.1.gem
ERROR: While executing gem ... (Gem::Exception)
    Unable to require openssl, install OpenSSL and rebuild ruby (preferred) or use non-HTTPS sources

原因：
缺少openssl，需要安装openssl包，我现在这里来安装一个openssl-1.0.1s.tar.gz（下载链接：http://www.openssl.org/source/）

解决方法步骤：
1.解压在/usr/local/src目录下，进入/usr/local/src/openssl-1.0.1s目录准备安装：

[root@localhost src]# tar -xzvf openssl-1.0.1s.tar.gz
[root@localhost src]# cd openssl-1.0.1s
[root@localhost openssl-1.0.1s]# ./config -fPIC --prefix=/usr/local/openssl enable-shared
[root@localhost openssl-1.0.1s]# ./config -t
[root@localhost openssl-1.0.1s]# make && make install

openssl的配置文件必须要配置-fPIC参数，如果没有该参数下面的安装中会出现问题！
安装完成，可以检测一下是否安装成功：

[root@localhost openssl-1.0.1s]# openssl version

2.进入ruby源码[/usr/local/src/ruby-2.3.0]目录下的ext/openssl 目录：

[root@localhost openssl-1.0.1s]# cd ../ruby-2.3.0
[root@localhost ruby-2.3.0]# cd ext/openssl
[root@localhost openssl]# ruby extconf.rb
checking for t_open() in -lnsl... no
checking for socket() in -lsocket... no
checking for assert.h... yes
checking for openssl/ssl.h... no

提示没有找到ssl.h, 因为出现了错误：openssl/ssl.h：没有那个文件或目录

[root@localhost openssl]# ruby extconf.rb --with-openssl-include=/usr/local/openssl/include/ --with-openssl-lib=/usr/local/openssl/lib
checking for t_open() in -lnsl... no
checking for socket() in -lsocket... no
checking for assert.h... yes
checking for openssl/ssl.h... yes
.............................................中间略.............................................
checking for EVP_CTRL_GCM_GET_TAG in openssl/evp.h... yes
creating extconf.h
creating Makefile

成功。

3.接下来并且将ruby 源码目录下的include目录软链接到 / 目录下：

[root@localhost openssl]# ln -s /usr/local/src/ruby-2.2.3/include /

接着再执行make，如果在配置openssl时没有-fPIC参数时就会出现如下错误

[root@localhost openssl]# make
gcc -shared -o openssl.so ossl_x509.o ossl_x509cert.o ossl_x509crl.o ossl_pkcs7.o ossl_cipher.o ossl_pkey_dh.o ossl_ssl_session.o ossl_x509attr.o ossl_x509ext.o ossl_ocsp.o ossl_asn1.o ossl_x509name.o ossl_x509revoked.o ossl_rand.o ossl_pkcs12.o ossl_x509store.o ossl_ssl.o ossl.o ossl_digest.o ossl_config.o ossl_pkcs5.o ossl_bio.o ossl_pkey_dsa.o ossl_pkey.o ossl_x509req.o ossl_pkey_ec.o ossl_hmac.o openssl_missing.o ossl_ns_spki.o ossl_pkey_rsa.o ossl_engine.o ossl_bn.o -L. -L/usr/local/ruby/lib -Wl,-R/usr/local/ruby/lib -L/usr/local/ssl/lib -Wl,-R/usr/local/ssl/lib -L. -rdynamic -Wl,-export-dynamic -lssl -lcrypto -lrt -ldl -lcrypt -lm -lc
/usr/bin/ld: /usr/local/ssl/lib/libssl.a(s2_meth.o): relocation R_X86_64_32 against `a local symbol'
can not be used when making a shared object; recompile with -fPIC
/usr/local/ssl/lib/libssl.a: could not read symbols: Bad value
collect2: ld returned 1 exit status
make: *** [openssl.so] Error 1

有配置-fPIC参数时就继续走下去：

[root@localhost openssl]# make
compiling ossl_pkey_dsa.c
compiling openssl_missing.c
compiling ossl_x509name.c
compiling ossl_pkey_rsa.c
.............................................中间略.............................................
compiling ossl_bn.c
compiling ossl.c
linking shared-object openssl.so

[root@localhost openssl]# make install
/usr/bin/install -c -m 0755 openssl.so /usr/local/ruby/lib/ruby/site_ruby/2.2.0/x86_64-linux
installing default openssl libraries

成功。

4.回过头来，这时候我们已经把配置集群遇到的各种问题已经解决好了，再次使用gem install 安装 ruby redis 接口：

# [root@localhost src]# gem install redis --version 3.0.0
# # 由于源的原因，可能下载失败，就手动下载下来安装
[root@localhost src]# gem install /usr/local/src/redis-3.2.1.gem
Successfully installed redis-3.2.1
Parsing documentation for redis-3.2.1
Installing ri documentation for redis-3.2.1
Done installing documentation for redis after 0 seconds
WARNING:  Unable to pull data from 'https://rubygems.org/': SSL_connect returned=1 errno=0 state=error: certificate verify failed (https://rubygems.org/specs.4.8.gz)
1 gem installed

可以看到这时ruby redis接口已经安装成功了；

当Redis也安装好，这时我们来做一个Redis集群测试，在一台服务器中创建了6个Redis实例，开启6个Redis服务。

[root@localhost redis-cluster]# redis-trib.rb create --replicas 1 127.0.0.1:7001 127.0.0.1:7002 127.0.0.1:7003 127.0.0.1:7004 127.0.0.1:7005 127.0.0.1:7006
>>> Creating cluster
>>> Performing hash slots allocation on 6 nodes...
Using 3 masters:
127.0.0.1:7001
127.0.0.1:7002
127.0.0.1:7003
Adding replica 127.0.0.1:7004 to 127.0.0.1:7001
Adding replica 127.0.0.1:7005 to 127.0.0.1:7002
Adding replica 127.0.0.1:7006 to 127.0.0.1:7003
M: e18c4d9b2a9c2b92b3695cb7236512bc3569349e 127.0.0.1:7001
   slots:0-5460 (5461 slots) master
M: bfd2c5320bfa800713e18b8f57900fd63995d7cf 127.0.0.1:7002
   slots:5461-10922 (5462 slots) master
M: 9d41b514413bcf348d55fe7239ce93b94fab7b01 127.0.0.1:7003
   slots:10923-16383 (5461 slots) master
S: fef13f9a028d8a5de2442f562aa88941eb591ba5 127.0.0.1:7004
   replicates e18c4d9b2a9c2b92b3695cb7236512bc3569349e
S: 7845903bdd01e2992877e27110bbbc7ff4036828 127.0.0.1:7005
   replicates bfd2c5320bfa800713e18b8f57900fd63995d7cf
S: c0becb06b09e957fd34fad5ae85dec15d0b59cd8 127.0.0.1:7006
   replicates 9d41b514413bcf348d55fe7239ce93b94fab7b01
Can I set the above configuration? (type 'yes' to accept): yes
>>> Nodes configuration updated
>>> Assign a different config epoch to each node
>>> Sending CLUSTER MEET messages to join the cluster
Waiting for the cluster to join.....
>>> Performing Cluster Check (using node 127.0.0.1:7001)
M: e18c4d9b2a9c2b92b3695cb7236512bc3569349e 127.0.0.1:7001
   slots:0-5460 (5461 slots) master
M: bfd2c5320bfa800713e18b8f57900fd63995d7cf 127.0.0.1:7002
   slots:5461-10922 (5462 slots) master
M: 9d41b514413bcf348d55fe7239ce93b94fab7b01 127.0.0.1:7003
   slots:10923-16383 (5461 slots) master
M: fef13f9a028d8a5de2442f562aa88941eb591ba5 127.0.0.1:7004
   slots: (0 slots) master
   replicates e18c4d9b2a9c2b92b3695cb7236512bc3569349e
M: 7845903bdd01e2992877e27110bbbc7ff4036828 127.0.0.1:7005
   slots: (0 slots) master
   replicates bfd2c5320bfa800713e18b8f57900fd63995d7cf
M: c0becb06b09e957fd34fad5ae85dec15d0b59cd8 127.0.0.1:7006
   slots: (0 slots) master
   replicates 9d41b514413bcf348d55fe7239ce93b94fab7b01
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
[root@localhost redis-cluster]# redis-trib.rb check
[ERR] Wrong number of arguments for specified sub command
[root@localhost redis-cluster]# redis-trib.rb check 127.0.0.1:7001
>>> Performing Cluster Check (using node 127.0.0.1:7001)
M: e18c4d9b2a9c2b92b3695cb7236512bc3569349e 127.0.0.1:7001
   slots:0-5460 (5461 slots) master
   1 additional replica(s)
S: c0becb06b09e957fd34fad5ae85dec15d0b59cd8 127.0.0.1:7006
   slots: (0 slots) slave
   replicates 9d41b514413bcf348d55fe7239ce93b94fab7b01
S: fef13f9a028d8a5de2442f562aa88941eb591ba5 127.0.0.1:7004
   slots: (0 slots) slave
   replicates e18c4d9b2a9c2b92b3695cb7236512bc3569349e
S: 7845903bdd01e2992877e27110bbbc7ff4036828 127.0.0.1:7005
   slots: (0 slots) slave
   replicates bfd2c5320bfa800713e18b8f57900fd63995d7cf
M: bfd2c5320bfa800713e18b8f57900fd63995d7cf 127.0.0.1:7002
   slots:5461-10922 (5462 slots) master
   1 additional replica(s)
M: 9d41b514413bcf348d55fe7239ce93b94fab7b01 127.0.0.1:7003
   slots:10923-16383 (5461 slots) master
   1 additional replica(s)
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.

这样就表示我们的集群（三主三从）创建成功了！

主节点：127.0.0.1:7001 127.0.0.1:7002 127.0.0.1:7003

从节点：127.0.0.1:7004 127.0.0.1:7005 127.0.0.1:7006