2020-01-24

Redis

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Docker搭建Redis集群

今天是除夕，但是我并有感受到像别人家那般浓厚的年味，我妈早早的做了几个菜，中午随便对付一下就算过了年了。入正题吧，今天主要是记录一下Docker搭建Redis集群的过程，在2017年的时候，当时接触到了中移在线的一个项目，因为考虑到高并发，所以就用到了Redis，但是当时都是手动基于Centos搭建和运维。

Redis的Dockerfile

我们既然我们要使用Docker来安装Redis,那么我们最好还是得对他的Dcokerfile还是需要有一定的了解。

FROM debian:buster-slim

# add our user and group first to make sure their IDs get assigned consistently, regardless of whatever dependencies get added
RUN groupadd -r -g 999 redis && useradd -r -g redis -u 999 redis

# grab gosu for easy step-down from root
# https://github.com/tianon/gosu/releases
ENV GOSU_VERSION 1.11
RUN set -eux; \
# save list of currently installed packages for later so we can clean up
	savedAptMark="$(apt-mark showmanual)"; \
	apt-get update; \
	apt-get install -y --no-install-recommends \
		ca-certificates \
		dirmngr \
		gnupg \
		wget \
	; \
	rm -rf /var/lib/apt/lists/*; \
	\
	dpkgArch="$(dpkg --print-architecture | awk -F- '{ print $NF }')"; \
	wget -O /usr/local/bin/gosu "https://github.com/tianon/gosu/releases/download/$GOSU_VERSION/gosu-$dpkgArch"; \
	wget -O /usr/local/bin/gosu.asc "https://github.com/tianon/gosu/releases/download/$GOSU_VERSION/gosu-$dpkgArch.asc"; \
	\
# verify the signature
	export GNUPGHOME="$(mktemp -d)"; \
	gpg --batch --keyserver hkps://keys.openpgp.org --recv-keys B42F6819007F00F88E364FD4036A9C25BF357DD4; \
	gpg --batch --verify /usr/local/bin/gosu.asc /usr/local/bin/gosu; \
	gpgconf --kill all; \
	rm -rf "$GNUPGHOME" /usr/local/bin/gosu.asc; \
	\
# clean up fetch dependencies
	apt-mark auto '.*' > /dev/null; \
	[ -z "$savedAptMark" ] || apt-mark manual $savedAptMark > /dev/null; \
	apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false; \
	\
	chmod +x /usr/local/bin/gosu; \
# verify that the binary works
	gosu --version; \
	gosu nobody true

ENV REDIS_VERSION 5.0.7
ENV REDIS_DOWNLOAD_URL http://download.redis.io/releases/redis-5.0.7.tar.gz
ENV REDIS_DOWNLOAD_SHA 61db74eabf6801f057fd24b590232f2f337d422280fd19486eca03be87d3a82b

RUN set -eux; \
	\
	savedAptMark="$(apt-mark showmanual)"; \
	apt-get update; \
	apt-get install -y --no-install-recommends \
		ca-certificates \
		wget \
		\
		gcc \
		libc6-dev \
		make \
	; \
	rm -rf /var/lib/apt/lists/*; \
	\
	wget -O redis.tar.gz "$REDIS_DOWNLOAD_URL"; \
	echo "$REDIS_DOWNLOAD_SHA *redis.tar.gz" | sha256sum -c -; \
	mkdir -p /usr/src/redis; \
	tar -xzf redis.tar.gz -C /usr/src/redis --strip-components=1; \
	rm redis.tar.gz; \
	\
# disable Redis protected mode [1] as it is unnecessary in context of Docker
# (ports are not automatically exposed when running inside Docker, but rather explicitly by specifying -p / -P)
# [1]: https://github.com/antirez/redis/commit/edd4d555df57dc84265fdfb4ef59a4678832f6da
	grep -q '^#define CONFIG_DEFAULT_PROTECTED_MODE 1$' /usr/src/redis/src/server.h; \
	sed -ri 's!^(#define CONFIG_DEFAULT_PROTECTED_MODE) 1$!\1 0!' /usr/src/redis/src/server.h; \
	grep -q '^#define CONFIG_DEFAULT_PROTECTED_MODE 0$' /usr/src/redis/src/server.h; \
# for future reference, we modify this directly in the source instead of just supplying a default configuration flag because apparently "if you specify any argument to redis-server, [it assumes] you are going to specify everything"
# see also https://github.com/docker-library/redis/issues/4#issuecomment-50780840
# (more exactly, this makes sure the default behavior of "save on SIGTERM" stays functional by default)
	\
	make -C /usr/src/redis -j "$(nproc)" all; \
	make -C /usr/src/redis install; \
	\
# TODO https://github.com/antirez/redis/pull/3494 (deduplicate "redis-server" copies)
	serverMd5="$(md5sum /usr/local/bin/redis-server | cut -d' ' -f1)"; export serverMd5; \
	find /usr/local/bin/redis* -maxdepth 0 \
		-type f -not -name redis-server \
		-exec sh -eux -c ' \
			md5="$(md5sum "$1" | cut -d" " -f1)"; \
			test "$md5" = "$serverMd5"; \
		' -- '{}' ';' \
		-exec ln -svfT 'redis-server' '{}' ';' \
	; \
	\
	rm -r /usr/src/redis; \
	\
	apt-mark auto '.*' > /dev/null; \
	[ -z "$savedAptMark" ] || apt-mark manual $savedAptMark > /dev/null; \
	find /usr/local -type f -executable -exec ldd '{}' ';' \
		| awk '/=>/ { print $(NF-1) }' \
		| sort -u \
		| xargs -r dpkg-query --search \
		| cut -d: -f1 \
		| sort -u \
		| xargs -r apt-mark manual \
	; \
	apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false; \
	\
	redis-cli --version; \
	redis-server --version

RUN mkdir /data && chown redis:redis /data
VOLUME /data
WORKDIR /data

COPY docker-entrypoint.sh /usr/local/bin/
ENTRYPOINT ["docker-entrypoint.sh"]

EXPOSE 6379
CMD ["redis-server"]

从代码中，我们能看出。它大概做了这几件事：

1.创建一个供Redis运行的redis用户。
2.下载Redis源文件并编译
3.设置运行目录、复制shell脚本并启动Redis

这里的ENTRYPOINT和CMD以为要一起写呢？有什么区别吗？这里我简单介绍一下这二者的作用，它们俩都是在启动容器的执行的命令，ENTRYPOINT是一定会执行，CMD就是执行一些默认的参数，当容器运行的时候，如果参数了其他参数则不会执行CMD命令。
我们再来看看docker-entrypoint.sh脚本的内容:

#!/bin/sh
set -e

# first arg is `-f` or `--some-option`
# or first arg is `something.conf`
if [ "${1#-}" != "$1" ] || [ "${1%.conf}" != "$1" ]; then
	set -- redis-server "$@"
fi

# allow the container to be started with `--user`
if [ "$1" = 'redis-server' -a "$(id -u)" = '0' ]; then
	find . \! -user redis -exec chown redis '{}' +
	exec gosu redis "$0" "$@"
fi

exec "$@"

可以看出，如果容器运行时带有redis-server的参数，就会执行最下面的语句。

基于Docker安装单实例Redis

我们先运行一个最最简单的Redis单实例:

[root@instance-p0a4erj8 ~]# docker run --name single-redis -p 16379:6379 -d redis
Unable to find image 'redis:latest' locally
latest: Pulling from library/redis
8ec398bc0356: Pull complete 
da01136793fa: Pull complete 
cf1486a2c0b8: Pull complete 
a44f7da98d9e: Pull complete 
c677fde73875: Pull complete 
727f8da63ac2: Pull complete 
Digest: sha256:90d44d431229683cadd75274e6fcb22c3e0396d149a8f8b7da9925021ee75c30
Status: Downloaded newer image for redis:latest
6cbde1e7d6d7511d2c0724d09ebf1f17c5823bbfc42821805b6be75c700063d5

现在就可以查看到运行的Docker容器

1
2
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[root@instance-p0a4erj8 ~]# docker ps -a
CONTAINER ID        IMAGE                                             COMMAND                  CREATED              STATUS                     PORTS                                                                            NAMES
6cbde1e7d6d7        redis                                             "docker-entrypoint.s…"   About a minute ago   Up About a minute          0.0.0.0:16379->6379/tcp                                                          single-redis

我们进入到容器连接到redis查看我们的基础信息：

[root@instance-p0a4erj8 ~]# sudo docker exec -it 6cbde1e7d6d7 /bin/bash
root@6cbde1e7d6d7:/data# redis-cli -h 127.0.0.1
127.0.0.1:6379> info
# Server
redis_version:5.0.7
redis_git_sha1:00000000
redis_git_dirty:0
redis_build_id:b671f408463590b9
redis_mode:standalone
os:Linux 3.10.0-957.27.2.el7.x86_64 x86_64
arch_bits:64
multiplexing_api:epoll
atomicvar_api:atomic-builtin
gcc_version:8.3.0
process_id:1
run_id:c55ee8eb658ae70d4bc1f87217a9ba14ef5d872c
tcp_port:6379
uptime_in_seconds:1404
uptime_in_days:0
hz:10
configured_hz:10
lru_clock:2792994
executable:/data/redis-server
config_file:

# Clients
connected_clients:3
client_recent_max_input_buffer:2
client_recent_max_output_buffer:0
blocked_clients:0

# Memory
used_memory:896128
used_memory_human:875.12K
used_memory_rss:2867200
used_memory_rss_human:2.73M
used_memory_peak:4995904
used_memory_peak_human:4.76M
used_memory_peak_perc:17.94%
used_memory_overhead:874802
used_memory_startup:791264
used_memory_dataset:21326
used_memory_dataset_perc:20.34%
allocator_allocated:1449240
allocator_active:1744896
allocator_resident:8658944
total_system_memory:4142325760
total_system_memory_human:3.86G
used_memory_lua:37888
used_memory_lua_human:37.00K
used_memory_scripts:0
used_memory_scripts_human:0B
number_of_cached_scripts:0
maxmemory:0
maxmemory_human:0B
maxmemory_policy:noeviction
allocator_frag_ratio:1.20
allocator_frag_bytes:295656
allocator_rss_ratio:4.96
allocator_rss_bytes:6914048
rss_overhead_ratio:0.33
rss_overhead_bytes:-5791744
mem_fragmentation_ratio:3.36
mem_fragmentation_bytes:2013072
mem_not_counted_for_evict:0
mem_replication_backlog:0
mem_clients_slaves:0
mem_clients_normal:83538
mem_aof_buffer:0
mem_allocator:jemalloc-5.1.0
active_defrag_running:0
lazyfree_pending_objects:0

# Persistence
loading:0
rdb_changes_since_last_save:0
rdb_bgsave_in_progress:0
rdb_last_save_time:1579849894
rdb_last_bgsave_status:ok
rdb_last_bgsave_time_sec:-1
rdb_current_bgsave_time_sec:-1
rdb_last_cow_size:0
aof_enabled:0
aof_rewrite_in_progress:0
aof_rewrite_scheduled:0
aof_last_rewrite_time_sec:-1
aof_current_rewrite_time_sec:-1
aof_last_bgrewrite_status:ok
aof_last_write_status:ok
aof_last_cow_size:0

# Stats
total_connections_received:3
total_commands_processed:3
instantaneous_ops_per_sec:0
total_net_input_bytes:59
total_net_output_bytes:17953
instantaneous_input_kbps:0.00
instantaneous_output_kbps:0.00
rejected_connections:0
sync_full:0
sync_partial_ok:0
sync_partial_err:0
expired_keys:0
expired_stale_perc:0.00
expired_time_cap_reached_count:0
evicted_keys:0
keyspace_hits:0
keyspace_misses:0
pubsub_channels:0
pubsub_patterns:0
latest_fork_usec:0
migrate_cached_sockets:0
slave_expires_tracked_keys:0
active_defrag_hits:0
active_defrag_misses:0
active_defrag_key_hits:0
active_defrag_key_misses:0

# Replication
role:master
connected_slaves:0
master_replid:1f4d9501e8ac6f6290436805ee7dae04972f6bc0
master_replid2:0000000000000000000000000000000000000000
master_repl_offset:0
second_repl_offset:-1
repl_backlog_active:0
repl_backlog_size:1048576
repl_backlog_first_byte_offset:0
repl_backlog_histlen:0

# CPU
used_cpu_sys:1.231650
used_cpu_user:1.380298
used_cpu_sys_children:0.003946
used_cpu_user_children:0.003628

# Cluster
cluster_enabled:0

# Keyspace
127.0.0.1:6379>

但是一般情况，我们肯定不会用默认配置来运行Redis,所以在运行时需要指定配置参数。比如数据存储路径呀、redis密码呀还有主从配置啊，等等。这里我们就修改redis.conf文件,给redis配置密码:

1	requirepass dockerredis

在启动的时候，我们加入启动参数:

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[root@instance-p0a4erj8 ~]#  docker run -p 16379:6379 --name single-redis -v /root/redis.conf:/usr/local/etc/redis.conf -d redis  redis-server /usr/local/etc/redis.conf
5ad95dab31df10d466e164f4dd305564ab68f77ddc63eec882d271aa3bc7338a

这是再登录我们的redis server就会提示需要输入密码:

[root@instance-p0a4erj8 ~]# sudo docker exec -it 5ad95dab31df  /bin/bash
root@5ad95dab31df:/data# redis-cli -h 127.0.0.1
127.0.0.1:6379> info
NOAUTH Authentication required.
127.0.0.1:6379>

输入密码即可操作:

1 2	127.0.0.1:6379> auth dockerredis OK