Redis 配置文件介绍——redis.conf

1. Units单位
   

   # 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# 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.

   
   ① 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
   ② 对大小写不敏感
   
   
2. INCLUDES包含
   

   ################################## 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.## Notice 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

   ① 和Struts2配置文件类似，可以通过includes包含其他的配置文件，redis.conf可以作为总闸，包含其他
   
   
   
   
3.  NETWORK
   

   ################################## 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.# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~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.protected-mode yes# 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 listen() backlog.## In high requests-per-second environments you need an high backlog in order# to avoid slow clients connections 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.## 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 /tmp/redis.sock# unixsocketperm 700# Close the connection after a client is idle for N seconds (0 to disable)timeout 0# 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) Take the connection alive from the point of view of network#    equipment in the middle.## 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

   ① bind ip地址的绑定，默认只允许本机访问（127.0.0.1）。
   ②port   端口号 
   ③tcp-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。在高并发开发环境下你需要一个高backlog值来避免慢客户端连接的问题。注意Linux内核会将这个值减少到/proc/sys/net/core/somaxconn的值，所以需要确认增大somaxconn和tcp_max_syn_backlog两个值来达到想要的效果。
   ④ timeout 会话超时时间，默认为0 ，不超时（不关闭会话）
   ⑤ tcp-keepalive 单位为秒，如果设置为0，则不会进行keepalive检测，建议设置为60（检测redis的网络通讯状态）
   
   
4. GENERAL通用【通用配置】
   

   ################################# 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# 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/nulllogfile ""# To enable logging to the system logger, just set 'syslog-enabled' to yes,# and optionally update the other syslog parameters to suit your needs.# syslog-enabled no# Specify the syslog identity.# syslog-ident redis# Specify the syslog facility. Must be USER or between LOCAL0-LOCAL7.# syslog-facility local0# 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'-1databases 16

   
   ① daemonize   决定redis是否后台运行的配置，默认 no （不开启），yes（开启）
   ② pidfile Redis进程PID文件所在路径
   ③ loglevel 日志级别，有四个级别（debug/verbose/notice/wrning）
   ④ syslog-enabled 是否把日志输出到syslog（系统日志）中
   ⑤ syslog-ident 指定syslog里的日志标志
   ⑥ syslog-facility 指定syslog设备，值可以是USER或LOCAL0-LOCAL7
   ⑦ databases redis默认分16个库
   
   
5. SNAPSHOTTING 快照
   

   ################################ 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 1save 300 10save 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 DBdbfilename 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 ./

   
   
   
6.  SECURITY安全【通用配置】
   

   ################################## 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.## requirepass foobared# Command renaming.## It is possible to change the name of dangerous commands in a shared# environment. For instance the CONFIG command may be renamed into something# hard to guess so that it will still be available for internal-use tools# but not available for general clients.## Example:## rename-command CONFIG b840fc02d524045429941cc15f59e41cb7be6c52## It is also possible to completely kill a command by renaming it into# an empty string:## rename-command CONFIG ""## Please note that changing the name of commands that are logged into the# AOF file or transmitted to slaves may cause problems.

   ① requirepass 密码，redis默认是不开启安全验证的，其目的是更关注与缓存这块而非安全
   备注：如果一旦设置了密码，意味着操作redis之前都必须通过 AUTH命令（auth  password） 进行授权验证。
   
   
7.  LIMITS限制【通用配置】
   

   ################################### LIMITS ##################################### 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'.## maxclients 10000# Don't use more memory than 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 cache, or to set# a hard memory limit for an instance (using the 'noeviction' policy).## WARNING: If you have slaves attached to an instance with maxmemory on,# the size of the output buffers needed to feed the slaves 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 slaves 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 slaves attached it is suggested that you set a lower# limit for maxmemory so that there is some free RAM on the system for slave# output buffers (but this is not needed if the policy is 'noeviction').## maxmemory <bytes># MAXMEMORY POLICY: how Redis will select what to remove when maxmemory# is reached. You can select among five behaviors:## volatile-lru -> remove the key with an expire set using an LRU algorithm# allkeys-lru -> remove any key according to the LRU algorithm# volatile-random -> remove a random key with 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 expire at all, just return an error on write operations## Note: with any of the above policies, Redis will return an error on write#       operations, when there are no suitable keys for eviction.##       At the date of writing these commands are: set setnx setex append#       incr decr rpush lpush rpushx lpushx linsert lset rpoplpush sadd#       sinter sinterstore sunion sunionstore sdiff sdiffstore zadd zincrby#       zunionstore zinterstore hset hsetnx hmset hincrby incrby decrby#       getset mset msetnx exec sort## The default is:## maxmemory-policy noeviction# LRU 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. For default Redis will check five keys and pick the one that was# used less 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 a bit more CPU. 3 is very fast but not very accurate.## maxmemory-samples 5

   ① maxclients 最大客户端连接数
   ② maxmemory 最大内存，单位<bytes>（字节）
   ③ maxmemory-policy 最大内存缓存过期清除策略
        备注：
   lru:标识最近使用的少
   生产中一般只建议选择1~5的选项。
        1)volatile-lru -> 使用LRU算法移除key，只对设置了过期时间的键
        2)allkeys-lru -> 使用LRU算法移除任何key
        3) 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
        4)allkeys-random -> 移除随机的key
        5) volatile-ttl ->  移除那些TTL值最小的key，即那些最近要过期的key
        6) noeviction -> 不进行移除。针对写操作，只是返回错误信息。
   ④ maxmemory-samples 设置最大内存样本数量，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并选中其中LRU的那个。
   
   
   
8. 常见配置 redis.conf介绍