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redis.conf配置文件介绍在Redis的使用过程，除了知道对Redis五种数据类型的操作方法之外，最主要的就是对redis.conf进行配置。
Redis 的配置文件位于 Redis 安装目录下，
1、units
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
表明unit的单位是不分大小写的。
# 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、Include
表明我们可以通过命令将多个.conf文件进行合并，格式：include /path/to/other.conf
和Spring配置文件类似，可以通过includes包含，redis.conf 可以作为总文件，可以包含其他文件！
# 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、loadmodule 加载模块
通过这里的 loadmodule 配置将引入自定义模块来新增一些功能。
# 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
4、NETWORK 网络设置
################################## NETWORK #####################################
.......
# IF YOU ARE SURE YOU WANT YOUR INSTANCE TO LISTEN TO ALL THE INTERFACES
# JUST COMMENT OUT THE FOLLOWING LINE.
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# 默认只能本机访问，如果是远程调用或者虚拟机调用，需要将其注释掉
bind 127.0.0.1 -::1
......
# 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.
# 如果你想要通过其他主机连接redis，那么你需要将protected-mode设为no
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.
# 6379是redis的默认端口号，你可以在这里修改redis的端口号
port 6379
......
# Close the connection after a client is idle for N seconds (0 to disable)
# 超时设置
timeout 0
5、GENERAL 通用
# 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 # 默认情况下，Redis不作为守护进程运行。需要开启的话，改为 yes
# 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 no # 可通过upstart和systemd管理Redis守护进程
# Note that on modern Linux systems "/run/redis.pid" is more conforming
# and should be used instead.
pidfile /var/run/redis_6379.pid # 以后台进程方式运行redis，则需要指定pid 文件
loglevel notice # 日志级别。可选项有：
# debug（记录大量日志信息，适用于开发、测试阶段）；
# verbose（较多日志信息）；
# notice（适量日志信息，使用于生产环境）；
# warning（仅有部分重要、关键信息才会被记录）。
logfile "" # 日志文件的位置，当指定为空字符串时，为标准输出
# 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 # 设置数据库的数目。默认的数据库是DB 0
# However it is possible to force the pre-4.0 behavior and always show a
# ASCII art logo in startup logs by setting the following option to yes.
always-show-logo yes # 是否总是显示logo
6、SNAPSHOPTING 快照
# 900秒（15分钟）内至少1个key值改变，才会进行保存（则进行数据库保存--持久化）
save 900 1
# 300秒（5分钟）内至少10个key值改变，才会进行保存（则进行数据库保存--持久化）
save 300 10
# 60秒（1分钟）内至少10000个key值改变，才会进行保存（则进行数据库保存--持久化）
save 60 10000
stop-writes-on-bgsave-error yes # 持久化出现错误后，是否依然进行继续进行工作
rdbcompression yes # 使用压缩rdb文件 yes：压缩，但是需要一些cpu的消耗。no：不压缩，需要更多的磁盘空间
rdbchecksum yes # 是否校验rdb文件，更有利于文件的容错性，但是在保存rdb文件的时候，会有大概10%的性能损耗
dbfilename dump.rdb # dbfilenamerdb文件名称
dir ./ # dir 数据目录，数据库的写入会在这个目录。rdb、aof文件也会写在这个目录（默认为当前目录）
7、REPLICATION 主从复制
# When a replica loses its connection with the master, or when the replication
# is still in progress, the replica can act in two different ways:
#
# 1) if replica-serve-stale-data is set to 'yes' (the default) the replica will
# still reply to client requests, possibly with out of date data, or the
# data set may just be empty if this is the first synchronization.
#
# 2) If replica-serve-stale-data is set to 'no' the replica will reply with
# an error "SYNC with master in progress" to all commands except:
# INFO, REPLICAOF, AUTH, PING, SHUTDOWN, REPLCONF, ROLE, CONFIG, SUBSCRIBE,
# UNSUBSCRIBE, PSUBSCRIBE, PUNSUBSCRIBE, PUBLISH, PUBSUB, COMMAND, POST,
# HOST and LATENCY.
#
replica-serve-stale-data yes
# Note: read only replicas are not designed to be exposed to untrusted clients
# on the internet. It's just a protection layer against misuse of the instance.
# Still a read only replica exports by default all the administrative commands
# such as CONFIG, DEBUG, and so forth. To a limited extent you can improve
# security of read only replicas using 'rename-command' to shadow all the
# administrative / dangerous commands.
replica-read-only yes
# With slow disks and fast (large bandwidth) networks, diskless replication
# works better.
repl-diskless-sync no
# The delay is specified in seconds, and by default is 5 seconds. To disable
# it entirely just set it to 0 seconds and the transfer will start ASAP.
repl-diskless-sync-delay 5
......
8、SECURITY 安全
# ACL LOG
#
# The ACL Log tracks failed commands and authentication events associated
# with ACLs. The ACL Log is useful to troubleshoot failed commands blocked
# by ACLs. The ACL Log is stored in memory. You can reclaim memory with
# ACL LOG RESET. Define the maximum entry length of the ACL Log below.
acllog-max-len 128
9、CLIENTS 限制
# 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.
#
# 设置客户端的最大连接数
# maxclients 10000
10、MEMORY MANAGEMENT内存管理
# 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').
#
# 你可以设置redis的最大内存（redis在未进行持久化之前，数据是存在内存中的，断电即失）
# maxmemory <bytes>
# 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:
#
# 设置key过期的策略
# maxmemory-policy noeviction
maxmemory-policy 六种策略
- volatile-lru：只最近最少使用算法，从设置了过期时间的键中选择空转时间最长的键值对清除掉；
- allkeys-lru ： 最近最少使用算法，从所有的键中选择空转时间最长的键值对清除；
- volatile-random：从设置了过期时间的键中，随机选择键进行清除；
- allkeys-random：所有的键中，随机选择键进行删除；
- volatile-ttl ： 从设置了过期时间的键中选择过期时间最早的键值对清除；
- noeviction ： 不做任何的清理工作，在redis的内存超过限制之后，所有的写入操作都会返回错误；但是读操作都能正常的进行;
