分布式缓存技术redis学习系列（一）——redis简介以及linux上的安装以及操作redis问题整理

一、redis简介及安装

1、redis简介

Redis是NoSQL（No Only SQL，非关系型数据库）的一种，NoSQL是以Key-Value的形式存储数据。当前主流的分布式缓存技术有redis,memcached,ssdb,MongoDB等。既可以把redis理解为理解为缓存技术，因为它的数据都是缓存在内从中的；也可以理解为数据库，因为redis可以周期性的将数据写入磁盘或者把操作追加到记录文件中。而我个人更倾向理解为缓存技术，因为当今互联网应用业务复杂、高并发、大数据的特性，正是各种缓存技术引入最终目的。

关于redis与传统关系型数据的对比、redis与memcached的对比、redis的优缺点，在此将不介绍，因为都各有各的好处，只有结合了具体的业务场景，才能深刻体会它们之间的差别和优缺点。下面开始redis在Linux上的安装。

2、linux下安装redis

1)、下载redis安装包

下载地址：http://redis.io/

或者命令行下载：

[root@localhost ftpuser]# wget http://download.redis.io/releases/redis-3.2.0.tar.gz[/code]1 1

2)、编译源程序
[root@localhost ftpuser]# tar zxvf redis-3.2.0.tar.gz
[root@localhost ftpuser]# cd redis-3.2.0
[root@localhost redis-3.2.0]# make
[root@localhost redis-3.2.0]# cd src && make install
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创建目录存放redis配置文件和命令文件
[root@localhost redis-3.2.0]# mkdir -p /usr/local/redis/conf
[root@localhost redis-3.2.0]# mkdir -p /usr/local/redis/bin
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移动配置文件和命令文件到上面创建的地址
[root@localhost redis-3.2.0]# mv redis.conf /usr/local/redis/conf
[root@localhost redis-3.2.0]# cd src
[root@localhost src]# cp mkreleasehdr.sh redis-benchmark redis-check-aof redis-check-rdb redis-cli redis-server redis-sentinel redis-trib.rb /usr/local/redis/bin
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注：如果不移动，操作的redis.conf配置文件在redis的根目录，操作相关命令在根下的src下面

除此之外，一般还创建run、log、rdb、aof文件夹，分别用于存放运行进程id(pid)、log日志、持久化RDB方式二进制快照文件dump.rdb(持久化AOF方式数据文件appendonly.aof、集群节点配置文件nodes-6379.conf也都会生成到rdb这个文件夹中，与dump.rdb同目录存储)，这些都需要修改redis.conf配置文件中默认的路径。

运行端口pid以及日志log：
################################# GENERAL #####################################

# By default Redis does not run as a daemon. Use 'yes' if you need it.
# Note that Redis will write a pid file in /var/run/redis.pid when daemonized.
daemonize no

# If you run Redis from upstart or systemd, Redis can interact with your
# supervision tree. Options:
#   supervised no      - no supervision interaction
#   supervised upstart - signal upstart by putting Redis into SIGSTOP mode
#   supervised systemd - signal systemd by writing READY=1 to $NOTIFY_SOCKET
#   supervised auto    - detect upstart or systemd method based on
#                        UPSTART_JOB or NOTIFY_SOCKET environment variables
# Note: these supervision methods only signal "process is ready."
#       They do not enable continuous liveness pings back to your supervisor.
supervised no

# If a pid file is specified, Redis writes it where specified at startup
# and removes it at exit.
#
# When the server runs non daemonized, no pid file is created if none is
# specified in the configuration. When the server is daemonized, the pid file
# is used even if not specified, defaulting to "/var/run/redis.pid".
#
# Creating a pid file is best effort: if Redis is not able to create it
# nothing bad happens, the server will start and run normally.
# pidfile /var/run/redis_6379.pid
pidfile "/usr/local/redis/run/redis_6379.pid"

# Specify the server verbosity level.
# This can be one of:
# debug (a lot of information, useful for development/testing)
# verbose (many rarely useful info, but not a mess like the debug level)
# notice (moderately verbose, what you want in production probably)
# warning (only very important / critical messages are logged)
loglevel notice

# Specify the log file name. Also the empty string can be used to force
# Redis to log on the standard output. Note that if you use standard
# output for logging but daemonize, logs will be sent to /dev/null
logfile "/usr/local/redis/log/redis.log"
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快照rdb：
################################ SNAPSHOTTING  ################################
#
# Save the DB on disk:
#
#   save <seconds> <changes>
#
#   Will save the DB if both the given number of seconds and the given
#   number of write operations against the DB occurred.
#
#   In the example below the behaviour will be to save:
#   after 900 sec (15 min) if at least 1 key changed
#   after 300 sec (5 min) if at least 10 keys changed
#   after 60 sec if at least 10000 keys changed
#
#   Note: you can disable saving completely by commenting out all "save" lines.
#
#   It is also possible to remove all the previously configured save
#   points by adding a save directive with a single empty string argument
#   like in the following example:
#
#   save ""

save 900 1
save 300 10
save 60 10000

# By default Redis will stop accepting writes if RDB snapshots are enabled
# (at least one save point) and the latest background save failed.
# This will make the user aware (in a hard way) that data is not persisting
# on disk properly, otherwise chances are that no one will notice and some
# disaster will happen.
#
# If the background saving process will start working again Redis will
# automatically allow writes again.
#
# However if you have setup your proper monitoring of the Redis server
# and persistence, you may want to disable this feature so that Redis will
# continue to work as usual even if there are problems with disk,
# permissions, and so forth.
stop-writes-on-bgsave-error yes

# Compress string objects using LZF when dump .rdb databases?
# For default that's set to 'yes' as it's almost always a win.
# If you want to save some CPU in the saving child set it to 'no' but
# the dataset will likely be bigger if you have compressible values or keys.
rdbcompression yes

# Since version 5 of RDB a CRC64 checksum is placed at the end of the file.
# This makes the format more resistant to corruption but there is a performance
# hit to pay (around 10%) when saving and loading RDB files, so you can disable it
# for maximum performances.
#
# RDB files created with checksum disabled have a checksum of zero that will
# tell the loading code to skip the check.
rdbchecksum yes

# The filename where to dump the DB
dbfilename dump.rdb

# The working directory.
#
# The DB will be written inside this directory, with the filename specified
# above using the 'dbfilename' configuration directive.
#
# The Append Only File will also be created inside this directory.
#
# Note that you must specify a directory here, not a file name.
# dir ./
dir "/usr/local/redis/rdb"
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3)、启动redis服务，主要有两种方式：

方式一：直接启动
#加上`&`号使redis以后台程序方式运行
[root@localhost src]# redis-server &
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方式二：指定配置文件启动
[root@localhost src]# redis-server ../redis.conf &
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如上，启动redis服务需要指定配置文件，也可以需要修改redis.conf文件，daemonize no —- >daemonize yes实现后台启动。 

redis服务端默认链接端口是6379，最好也将IP绑定为本机IP。

4)、验证是否启动成功
[root@localhost ~]# ps -ef | grep redis
#或者
[root@localhost ~]# netstat -tunpl | grep 6379
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5)、客户端连接
[root@localhost src]# redis-cli
#远程连接方式
[root@localhost src]# redis-cli -h 127.0.0.1 -p 6379
redis> set foo bar
OK
redis> get foo
"bar"
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6)、停止redis服务
[root@localhost src]# redis-cli shutdown
#或者
[root@localhost ~]# pkill redis-server
#或者
[root@localhost ~]# kill -9 PID
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以上为转载内容，来源于：http://www.cnblogs.com/hjwublog/p/5637150.html

=============================分割线：验证上述过程(远程连接时)发现的问题：一波三折======================================

二、操作redis发现的问题
#启动redis服务，尝试远程连接：
[root@localhost src]# redis-server
#远程连接
[root@localhost src]# redis-cli -h 127.0.0.1 -p 6379
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1、第一波：先看一段异常
(error) DENIED Redis is running in protected mode because protected mode is enabled, no bind address was specified, no authentication password is requested to clients.
In this mode connections are only accepted from the loopback interface.
If you want to connect from external computers to Redis you may adopt one of the following solutions:
1) Just disable protected mode sending the command 'CONFIG SET protected-mode no' from the loopback interface by connecting to Redis from the same host the server is running, however MAKE SURE Redis is not publicly accessible from internet if you do so. Use CONFIG REWRITE to make this change permanent.
2) Alternatively you can just disable the protected mode by editing the Redis configuration file, and setting the protected mode option to 'no', and then restarting the server.
3) If you started the server manually just for testing, restart it with the '--protected-mode no' option.
4) Setup a bind address or an authentication password. NOTE: You only need to do one of the above things in order for the server to start accepting connections from the outside.
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所抛出的异常已经给出了详细原因：
redis是在protected mode下运行的；
经查询可知，在redis3.2之后，redis增加了protected mode模式，是为了禁止公网访问redis cache，加强redis安全。
同时redis默认只允许本地访问。

综合异常信息里面给出的解决方案，我选择方案2，修改redis.conf配置文件，将protected mode yes修改为no，同时将redis默认只允许本地访问的配置注释[# bind 127.0.0.1]，修改redis.conf内容如下：
################################## NETWORK #####################################

# By default, if no "bind" configuration directive is specified, Redis listens
# for connections from all the network interfaces available on the server.
# It is possible to listen to just one or multiple selected interfaces using
# the "bind" configuration directive, followed by one or more IP addresses.
#
# Examples:
#
# bind 192.168.1.100 10.0.0.1
# bind 127.0.0.1 ::1
#
# ~~~ WARNING ~~~ If the computer running Redis is directly exposed to the
# internet, binding to all the interfaces is dangerous and will expose the
# instance to everybody on the internet. So by default we uncomment the
# following bind directive, that will force Redis to listen only into
# the IPv4 lookback interface address (this means Redis will be able to
# accept connections only from clients running into the same computer it
# is running).
#
# IF YOU ARE SURE YOU WANT YOUR INSTANCE TO LISTEN TO ALL THE INTERFACES
# JUST COMMENT THE FOLLOWING LINE.
# ~~~~~~~~~~~~~~~~~~~~~~~~~~将可以访问的ip绑定注释掉~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# bind 127.0.0.1

# Protected mode is a layer of security protection, in order to avoid that
# Redis instances left open on the internet are accessed and exploited.
#
# When protected mode is on and if:
#
# 1) The server is not binding explicitly to a set of addresses using the
#    "bind" directive.
# 2) No password is configured.
#
# The server only accepts connections from clients connecting from the
# IPv4 and IPv6 loopback addresses 127.0.0.1 and ::1, and from Unix domain
# sockets.
#
# By default protected mode is enabled. You should disable it only if
# you are sure you want clients from other hosts to connect to Redis
# even if no authentication is configured, nor a specific set of interfaces
# are explicitly listed using the "bind" directive.
# ~~~~~~~~~~~~~~~~~~~~~~~~~~将protected-mode yes修改为protected-mode no~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# protected-mode yes
protected-mode no
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或者直接把bind的地址更改为服务器本机ip，注意不是127.0.0.1的形式，是真实的ip，这样不用修改protected-mode 也没有关系，因为默认情况，127.0.0.1是受保护的ip，只能本机访问。

重启redis服务，尝试远程连接：
[root@localhost src]# redis-server
[root@localhost src]# redis-cli -h 127.0.0.1 -p 6379
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注意：是不是发现结果是一样的，上面的异常依然存在，这个是因为启动redis的方式造成的。

按照方式一启动，修改redis.conf文件不起作用，需要本地登录redis客户端，然后采用异常里面提供的方案1，即通过命令修改，CONFIG SET protected-mode no，具体执行如下：
#启动redis服务
[root@localhost src]# redis-server
#本地登录客户端
[root@localhost src]# redis-cli -p 6379
#命令修改protected-mode为no
127.0.0.1:6379> CONFIG SET protected-mode no
#远程登录
[root@localhost src]# redis-cli -h 127.0.0.1 -p 6379
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如果就想通过修改redis.conf配置文件来实现远程登录(即按照异常里面的方案2操作)，那么启动redis服务的方式，就应该选择方式二，需要指定redis.conf配置启动，这个比较好理解，你修改了哪个，我就用哪个启动，具体操作如下：
#先修改redis.conf配置文件，修改内容看上面代码
#指定redis.conf配置文件启动redis服务
[root@localhost src]# redis-server ../redis.conf
#远程登录
[root@localhost src]# redis-cli -h 127.0.0.1 -p 6379
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上面两种方式结果一切正常。

2、第二波：修改6379默认端口
redis默认使用端口为6379，意思是说：使用redis-server、redis-cli、redis-cli shutdown都使用6379端口，如果将redis.conf端口修改为6389，然后执行以下操作：
#不能使用redis-server直接启动，否则redis.conf配置文件修改无效
#指定配置文件启动
[root@localhost src]# redis-server ../redis.conf
6081:M 25 Aug 11:02:21.488 * The server is now ready to accept connections on port 6389

[root@localhost src]# redis-cli
Could not connect to Redis at 127.0.0.1:6379: Connection refused

[root@localhost src]# redis-cli shutdown
Could not connect to Redis at 127.0.0.1:6379: Connection refused
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因为默认使用了6379端口，所以此处需要为其显示指定修改后的6389端口：
#客户端登录
[root@localhost src]# redis-cli -p 6389
127.0.0.1:6389>

#停止redis服务
[root@localhost src]# redis-cli -p 6389  shutdown
6081:M 25 Aug 11:02:21.488 * The server is now ready to accept connections on port 6389
6081:M 25 Aug 11:07:56.652 # User requested shutdown...
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3、第三波：添加密码认证，开放requirepass及对应异常NOAUTH Authentication required.
远程连接默认是无权限认证的，添加权限认证，需修改redis.conf配置文件，内容如下：
################################## SECURITY ###################################

# Require clients to issue AUTH <PASSWORD> before processing any other
# commands.  This might be useful in environments in which you do not trust
# others with access to the host running redis-server.
#
# This should stay commented out for backward compatibility and because most
# people do not need auth (e.g. they run their own servers).
#
# Warning: since Redis is pretty fast an outside user can try up to
# 150k passwords per second against a good box. This means that you should
# use a very strong password otherwise it will be very easy to break.
#
# ~~~~~~~~~~~~~~~~~~~~~~~~~~将requirepass foobared权限认证开放~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# requirepass foobared
requirepass foobared
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#指定配置文件启动
[root@localhost src]# redis-server ../redis.conf

#远程登录
[root@localhost src]# redis-cli -h 127.0.0.1 -p 6389 -a foobared
127.0.0.1:6389>
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除了在登录时通过 -a 参数制定密码外，还可以登录时不指定密码，而在执行操作前进行认证：
[root@localhost src]# redis-cli -h 127.0.0.1 -p 6389
127.0.0.1:6389> config get requirepass
(error) NOAUTH Authentication required.
127.0.0.1:6389> auth foobared
OK
127.0.0.1:6389> config get requirepass
1) "requirepass"
2) "foobared"
127.0.0.1:6389>
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注：(error) NOAUTH Authentication required.指的是开放了权限验证，但连接或者执行时没有使用密码。

3、第四波：Caused by: java.net.SocketTimeoutException: connect timed out
抛出这样的异常，可以从一下几个方面去排查：
ping redis服务ip，是否可以ping通
telnet redis端口，要确保redis服务正在使用的6379或者6389等端口有没有被防火墙屏蔽
其它

===============补充====================== 

通常的配置如下：

//绑定服务器本地只是ip 

bind 192.168.1.222

//绑定端口号，默认6379 

port 6381

//客户端连接超时时间，如果为，则永不超时 

timeout 1000

//设置redis进程为守护进程启动，redis-server redis.conf & 效果一样 

daemonize yes

//设置守护进程启动之后，保存进程号的文件位置 

pidfile /usr/local/redis/master/6381/run/redis_6381.pid

//配置日志级别，debug、verbose、notice、warning 

loglevel debug

//配置日志文件存储地址，是一个文件 

logfile “/usr/local/redis/master/6381/logs/redis.log”

//rdb持久化机制，主从配置中，一般主服务器关闭rdb持久化，从服务器负责持久化，一般使用aof代替rdb模式，将save注释即可 

save 900 1 

save 300 10 

save 60 10000

//rdb持久化文件名称 

dbfilename dump.rdb

//rdb持久化文件保存地址，aof持久化也是用这个地址 

dir /usr/local/redis/master/6381/rdb

//将当前服务作为从服务器，隶属的主服务如下，如果是开启了集群模式，手动配置主从关系导致无法启动，需要将slaveof注释掉，由redis-trib负责分配主从关系 

slaveof 192.168.1.222 6379

//如果主服务有密码的话，配置主服务密码，集群模式，需要考虑主从切换的问题，所以建议主从密码一致或不启用 

masterauth 123

//从服务的读写能力，默认只读，主服务会忽略这个配置 

slave-read-only yes

//当前服务启用密码验证，集群模式，需要考虑主从切换的问题，所以建议主从密码一致或不启用 

requirepass 123

//启用aof持久化机制，推荐使用aof模式替换rdb模式 

appendonly yes

//aof持久化机制的文件名称 

appendfilename “appendonly.aof”

//aof持久化采用的默认机制，每秒持久化一次，还有always和no两种 

appendfsync everysec

//启动集群模式，注意不要手动配置主从关系 

cluster-enabled yes

//指定集群节点超时时间 

cluster-node-timeout 5000

//指定集群节点配置文件，默认使用的路径为上面配置的dir 

cluster-config-file nodes-6381.conf

================分割线=============

主从配置文件路径参考： 

/usr/local/redis/master/6379 

/usr/local/redis/slave/7031 

–redis.conf 服务配置文件 

–bin 负责存放命令文件 

–rdb 负责存放持久化文件 

–logs 负责存放日志 

–run 负责存放进程id

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集群配置文件路径参考：
/usr/local/redis-cluster/

--6379/
--6380/
--6381/
--7031/
--7032/
--7033/
--redis.conf 服务配置文件
--bin 负责存放命令文件
--rdb 负责存放持久化文件
--logs 负责存放日志
--run 负责存放进程id