前言
这部分我们介绍一下Redis 中的配置文件redis.conf 常用的部分
开头部分
告诉我们这是一个Redis 配置文件的示例文件
# Redis configuration file example.
以指定配置文件启动redis
在./redis-server的第一个参数跟上配置文件的路径
# Note that in order to read the configuration file, Redis must be
# started with the file path as first argument:
#
# ./redis-server /path/to/redis.conf
配置内存大小单位
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.
INCLUDES 部分
简介
引入公用配置文件，多实例的情况可以把公用的配置文件提取出来，最好按模块进行分开
################################## 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.
注意事项
“include”选项不会被来自admin或Redis Sentinel的“CONFIG REWRITE”重写掉。
- 如果多个文件对同选项作了设置。redis总是使用最后一次的设置，因此你最好把”include”放在文件的开始处，以避免在运行时被后面的文件重写。
- 如果相反，你希望使用”include”来覆盖这些配置选项，最好把它放在文章的结尾。
# 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
MODULES
简介
这是Redis 4.0之后引入的内容，可以对Redis 进行扩展，比如实现新的数据结构、对数据结构采用新的访问方式等（一般不用）
- 在项目启动时加载指定模块，如果模块无法加载，服务将被终止
- 可以加载多个模块。
# Load modules at startup. If the server is not able to load modules
# it will abort. It is possible to use multiple loadmodule directives.
#
# loadmodule /path/to/my_module.so
# loadmodule /path/to/other_module.so
NETWORK
bing
限定访问的主机地址默认仅允许本机访问。
bing 0.0.0.0任何ip都能访问- 生产环境中往往会限定自己的应用服务器
# By default, if no "bind" configuration directive is specified, Redis listens
# for connections from all available network interfaces on the host machine.
# It is possible to listen to just one or multiple selected interfaces using
# the "bind" configuration directive, followed by one or more IP addresses.
# Each address can be prefixed by "-", which means that redis will not fail to
# start if the address is not available. Being not available only refers to
# addresses that does not correspond to any network interfece. Addresses that
# are already in use will always fail, and unsupported protocols will always BE
# silently skipped.
#
# 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
protected-mode
安全防护模式，默认开启（建议开启）
- 如果没有指定bind指令，也没有配置密码，那么保护模式就开启，只允许本机访问。
- 可以
protected-mode no手动关闭或设置bind和密码后自动关闭（建议设置bind和密码）
# 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
port：端口号，默认是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
tcp-backlog：tcp连接队列长度
- 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
Unix socket
指定要用于侦听的Unix套接字的路径，没有默认值，所以默认不会监听socket。
# 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
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。
# Close the connection after a client is idle for N seconds (0 to disable)
timeout 0
tcp-keepalive
对访问客户端的一种心跳检测，每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
GENERAL 全局配置
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 no
supervised
是否从upstart或systemd运行Redis，默认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
# requires "expect stop" in your upstart job config
# supervised systemd - signal systemd by writing READY=1 to $NOTIFY_SOCKET
# on startup, and updating Redis status on a regular
# basis.
# 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 pings back to your supervisor.
#
# The default is "no". To run under upstart/systemd, you can simply uncomment
# the line below:
#
# supervised auto
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
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
# 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
logfile
日志文件保存路径和名称
# 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 ""
databases
数据库数量，默认16，可以使用select <dbid>命令切换数据库
# 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
以上就是GENERAL 常用配置，更多请查看redis.conf 的有关内容
SECURITY
Redis一般做的是缓存，不是安全，而且系统会认为Linux是在安全的环境下，所以安全这边我们主要了解如何设置redis的密码
requirepass
修改密码：放开# requirepass foobared的注释，将foobared 修改为自己想要的密码
# IMPORTANT NOTE: starting with Redis 6 "requirepass" is just a compatibility
# layer on top of the new ACL system. The option effect will be just setting
# the password for the default user. Clients will still authenticate using
# AUTH <password> as usually, or more explicitly with AUTH default <password>
# if they follow the new protocol: both will work.
#
# The requirepass is not compatable with aclfile option and the ACL LOAD
# command, these will cause requirepass to be ignored.
#
# requirepass foobared
CLIENTS
maxclients
设置redis同时可以与多少个客户端进行连接。默认10000
如果达到了指定限制，redis则会拒绝新的连接请求，并且向这些连接请求方发出“max number of clients reached”以作回应。
################################### 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
MEMORY MANAGEMENT
maxmemory
将内存使用限制设置为指定的字节数。
- 设置redis可以使用的内存量。一旦到达内存使用上限，redis将会试图删除一些key，删除策略可以通过maxmemory-policy来指定。
- 如果Redis不能根据政策删除key，或者当策略是设置为'noeviction'，当使用占用更多内存的命令，如SET、LPUSH等，Redis将开始抛出错误，并将只执行只读命令，如GET。
- 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>
maxmemory-policy
key删除策略
- volatile-lru：使用LRU算法移除key，只对设置了过期时间的键；（最近最少使用）
- allkeys-lru：在所有集合key中，使用LRU算法移除key
- volatile-random：在过期集合中移除随机的key，只对设置了过期时间的键
- allkeys-random：在所有集合key中，移除随机的key
- volatile-ttl：移除那些TTL值最小的key，即那些最近要过期的key
- noeviction：不进行移除。针对写操作，只是返回错误信息
# MAXMEMORY POLICY: how Redis will select what to remove when maxmemory
# is reached. You can select one from the following behaviors:
#
# volatile-lru -> Evict using approximated LRU, only keys with an expire set.
# allkeys-lru -> Evict any key using approximated LRU.
# volatile-lfu -> Evict using approximated LFU, only keys with an expire set.
# allkeys-lfu -> Evict any key using approximated LFU.
# volatile-random -> Remove a random key having an expire set.
# allkeys-random -> Remove a random key, any key.
# volatile-ttl -> Remove the key with the nearest expire time (minor TTL)
# noeviction -> Don't evict anything, just return an error on write operations.
#
# LRU means Least Recently Used
# LFU means Least Frequently Used
#
# Both LRU, LFU and volatile-ttl are implemented using approximated
# randomized algorithms.
#
# Note: with any of the above policies, when there are no suitable keys for
# eviction, Redis will return an error on write operations that require
# more memory. These are usually commands that create new keys, add data or
# modify existing keys. A few examples are: SET, INCR, HSET, LPUSH, SUNIONSTORE,
# SORT (due to the STORE argument), and EXEC (if the transaction includes any
# command that requires memory).
#
# The default is:
#
# maxmemory-policy noeviction
maxmemory-samples
设置样本数量，LRU算法和最小TTL算法都并非是精确的算法，而是估算值，所以你可以设置样本的大小，redis默认会检查这么多个key并选择其中LRU的那个。
一般设置3到7的数字，数值越小样本越不准确，但性能消耗越小。
# LRU, LFU and minimal TTL algorithms are not precise algorithms but approximated
# algorithms (in order to save memory), so you can tune it for speed or
# accuracy. By default Redis will check five keys and pick the one that was
# used least recently, you can change the sample size using the following
# configuration directive.
#
# The default of 5 produces good enough results. 10 Approximates very closely
# true LRU but costs more CPU. 3 is faster but not very accurate.
#
# maxmemory-samples 5
# Eviction processing is designed to function well with the default setting.
# If there is an unusually large amount of write traffic, this value may need to
# be increased. Decreasing this value may reduce latency at the risk of
# eviction processing effectiveness
# 0 = minimum latency, 10 = default, 100 = process without regard to latency
#
# maxmemory-eviction-tenacity 10
以上就是Redis 中常用的配置文件，有关更多配置，请参考redis.conf 中的注释。