Redis 配置文件
/etc/redis.conf
1、Units 单位
配置大小单位，开头定义了一些基本的度量单位，只支持 bytes，不支持 bit
大小写不敏感
# Note on units: when memory size is needed, it is possible to specify
# it in the usual form of 1k 5GB 4M and so forth:
#
# 1k => 1000 bytes
# 1kb => 1024 bytes
# 1m => 1000000 bytes
# 1mb => 1024*1024 bytes
# 1g => 1000000000 bytes
# 1gb => 1024*1024*1024 bytes
#
# units are case insensitive so 1GB 1Gb 1gB are all the same.
2、INCLUDES 包含
类似 jsp 中的 include，多实例的情况可以把公用的配置文件提取出来。
################################## INCLUDES ###################################
# Include one or more other config files here. This is useful if you
# have a standard template that goes to all Redis servers but also need
# to customize a few per-server settings. Include files can include
# other files, so use this wisely.
#
# Note that option "include" won't be rewritten by command "CONFIG REWRITE"
# from admin or Redis Sentinel. Since Redis always uses the last processed
# line as value of a configuration directive, you'd better put includes
# at the beginning of this file to avoid overwriting config change at runtime.
#
# If instead you are interested in using includes to override configuration
# options, it is better to use include as the last line.
#
# include /path/to/local.conf
# include /path/to/other.conf
3、网络配置相关
3.1、band
默认情况 bind=127.0.0.1 只能接受本机的访问请求；
不写的情况下，无限制接受任何 ip 地址的访问；
生产环境肯定要写你应用服务器的地址；服务器是需要远程访问的，所以需要将其注释掉。
# Examples:
#
# bind 192.168.1.100 10.0.0.1 # listens on two specific IPv4 addresses
# bind 127.0.0.1 ::1 # listens on loopback IPv4 and IPv6
# bind * -::* # like the default, all available interfaces
#
# ~~~ 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 on the
# IPv4 and IPv6 (if available) loopback interface addresses (this means Redis
# will only be able to accept client connections from the same host that it is
# running on).
#
# IF YOU ARE SURE YOU WANT YOUR INSTANCE TO LISTEN TO ALL THE INTERFACES
# JUST COMMENT OUT THE FOLLOWING LINE.
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
bind 127.0.0.1 -::1
将 bind 127.0.0.1 -::1 注释掉。允许其他 ip 的访问。
3.2、protected-mode
如果开启了 protected-mode，那么在没有设定 bind ip 且没有设密码的情况下，Redis 只允许接受本机的响应；
将本机访问保护模式设置 no。
# 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.
protected-mode yes
3.3、Port
端口号，默认 6379
# Accept connections on the specified port, default is 6379 (IANA #815344).
# If port 0 is specified Redis will not listen on a TCP socket.
port 6379
3.4、tcp-backlog
设置 tcp 的 backlog，backlog 其实是一个连接队列，backlog 队列总和 = 未完成三次握手队列 + 已经完成三次握手队列。
在高并发环境下你需要一个高 backlog 值来避免慢客户端连接问题。
注意 Linux 内核会将这个值减小到 /proc/sys/net/core/somaxconn 的值（128），所以需要确认增
大 /proc/sys/net/core/somaxconn和/proc/sys/net/ipv4/tcp_max_syn_backlog（128）两个值来达到想要的效果。
# TCP listen() backlog.
#
# In high requests-per-second environments you need a high backlog in order
# to avoid slow clients connection issues. Note that the Linux kernel
# will silently truncate it to the value of /proc/sys/net/core/somaxconn so
# make sure to raise both the value of somaxconn and tcp_max_syn_backlog
# in order to get the desired effect.
tcp-backlog 511
3.5、timeout
一个空闲的客户端维持多少秒会关闭，0 表示关闭该功能。即永不关闭。
# Unix socket.
#
# Specify the path for the Unix socket that will be used to listen for
# incoming connections. There is no default, so Redis will not listen
# on a unix socket when not specified.
#
# unixsocket /run/redis.sock
# unixsocketperm 700
# Close the connection after a client is idle for N seconds (0 to disable)
timeout 0
3.6、tcp-keepalive
对访问客户端的一种心跳检测，每个 n 秒检测一次。
单位为秒，如果设置为 0，则不会进行 Keepalive 检测，建议设置成 60。
# TCP keepalive.
#
# If non-zero, use SO_KEEPALIVE to send TCP ACKs to clients in absence
# of communication. This is useful for two reasons:
#
# 1) Detect dead peers.
# 2) Force network equipment in the middle to consider the connection to be
# alive.
#
# On Linux, the specified value (in seconds) is the period used to send ACKs.
# Note that to close the connection the double of the time is needed.
# On other kernels the period depends on the kernel configuration.
#
# A reasonable value for this option is 300 seconds, which is the new
# Redis default starting with Redis 3.2.1.
tcp-keepalive 300
3.7、GENERAL 通用
3.7.1、daemonize
是否为后台进程，设置为 yes；
守护进程，后台启动。
# 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.
# When Redis is supervised by upstart or systemd, this parameter has no impact.
daemonize yes
3.7.2、pidfile
存放 pid 文件的位置，每个实例会产生一个不同的 pid 文件。
# 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.
#
# Note that on modern Linux systems "/run/redis.pid" is more conforming
# and should be used instead.
pidfile /var/run/redis_6379.pid
3.7.3、loglevel
指定日志记录级别，Redis 总共支持四个级别：debug、verbose、notice、warning，默认为 notice；
四个级别根据使用阶段来选择，生产环境选择 notice 或者 warning。
# 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
3.7.4、logfile
日志文件名称。
# 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 ""
3.7.5、databases
设定库的数量 默认16，默认数据库为 0，可以使用 SELECT <dbid> 命令在连接上指定数据库 id。
# Set the number of databases. The default database is DB 0, you can select
# a different one on a per-connection basis using SELECT <dbid> where
# dbid is a number between 0 and 'databases'-1
databases 16
3.8、SECURITY 安全
3.8.1、设置密码
# The requirepass is not compatable with aclfile option and the ACL LOAD
# command, these will cause requirepass to be ignored.
#
# requirepass foobared
访问密码的查看、设置和取消；
在命令中设置密码，只是临时的。重启 redis 服务器，密码就还原了。
永久设置，需要再配置文件中进行设置。
3.9、LIMIT 限制
3.9.1、maxclients
################################### CLIENTS ####################################
# Set the max number of connected clients at the same time. By default
# this limit is set to 10000 clients, however if the Redis server is not
# able to configure the process file limit to allow for the specified limit
# the max number of allowed clients is set to the current file limit
# minus 32 (as Redis reserves a few file descriptors for internal uses).
#
# Once the limit is reached Redis will close all the new connections sending
# an error 'max number of clients reached'.
#
# IMPORTANT: When Redis Cluster is used, the max number of connections is also
# shared with the cluster bus: every node in the cluster will use two
# connections, one incoming and another outgoing. It is important to size the
# limit accordingly in case of very large clusters.
#
# maxclients 10000
3.9.2、maxmemory
-
建议必须设置，否则，将内存占满，造成服务器宕机； -
设置 redis 可以使用的内存量。一旦到达内存使用上限，redis 将会试图移除内部数据，移除规则可以通过 maxmemory- policy 来指定； -
如果 redis 无法根据移除规则来移除内存中的数据，或者设置了 “不允许移除”，那么 redis 则会针对那些需要申请内存的指令 返回错误信息，比如 SET、LPUSH 等； -
但是对于无内存申请的指令，仍然会正常响应，比如 GET 等。如果你的 redis 是主 redis（说明你的 redis 有从 redis），那 么在设置内存使用上限时，需要在系统中留出一些内存空间给同步队列缓存，只有在你设置的是 “不移除” 的情况下，才不用 考虑这个因素。
############################## MEMORY MANAGEMENT ################################
# Set a memory usage limit to the specified amount of bytes.
# When the memory limit is reached Redis will try to remove keys
# according to the eviction policy selected (see maxmemory-policy).
#
# If Redis can't remove keys according to the policy, or if the policy is
# set to 'noeviction', Redis will start to reply with errors to commands
# that would use more memory, like SET, LPUSH, and so on, and will continue
# to reply to read-only commands like GET.
#
# This option is usually useful when using Redis as an LRU or LFU cache, or to
# set a hard memory limit for an instance (using the 'noeviction' policy).
#
# WARNING: If you have replicas attached to an instance with maxmemory on,
# the size of the output buffers needed to feed the replicas are subtracted
# from the used memory count, so that network problems / resyncs will
# not trigger a loop where keys are evicted, and in turn the output
# buffer of replicas is full with DELs of keys evicted triggering the deletion
# of more keys, and so forth until the database is completely emptied.
#
# In short... if you have replicas attached it is suggested that you set a lower
# limit for maxmemory so that there is some free RAM on the system for replica
# output buffers (but this is not needed if the policy is 'noeviction').
#
# maxmemory <bytes>
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