Compile and install Redis use systemd management

surroundings

THE	redis version	Firewall and selinux
CentOS7	4.0.14	shut down

installation steps

Pre-installation equipment

1.因为redis是用C编写的，所以需要安装gcc
#yum -y install gcc
2.下载redis源码包
#wget -P /usr/local/src/ http://download.redis.io/releases/redis-4.0.14.tar.gz

Compile and install

#cd /usr/local/src/
#tar xf redis-4.0.14.tar.gz
#cd redis-4.0.14
#make PREFIX=/apps/redis install #PREFIX表示指定redis的安装目录
#mkdir /apps/redis/{etc,logs,data,run} #创建配置文件、日志、数据等目录
#cp redis.conf /apps/redis/etc/

Edit redis service startup script that uses systemd manage the service

Note: The script is generated by the service to get from redis yum install file came after minor modifications by the

#cat > /usr/lib/systemd/system/redis.service <<EOF
[Unit]
Description=Redis persistent key-value database
After=network.target
After=network-online.target
Wants=network-online.target

[Service]
ExecStart=/apps/redis/bin/redis-server /apps/redis/etc/redis.conf --supervised systemd
ExecStop=/usr/libexec/redis-shutdown
Type=notify
User=redis
Group=redis
RuntimeDirectory=redis
RuntimeDirectoryMode=0755
LimitNOFILE=65536

[Install]
WantedBy=multi-user.target
EOF

Note: This script is closed redis service is done by another script / usr / libexec / redis-shutdown, yum install redis have the script, if it is compiled and installed redis not the script, which reads as follows:

#cat /usr/libexec/redis-shutdown 
#!/bin/bash
#
# Wrapper to close properly redis and sentinel
test x"$REDIS_DEBUG" != x && set -x

REDIS_CLI=/usr/bin/redis-cli

# Retrieve service name
SERVICE_NAME="$1"
if [ -z "$SERVICE_NAME" ]; then
   SERVICE_NAME=redis
fi

# Get the proper config file based on service name
CONFIG_FILE="/apps/redis/etc/$SERVICE_NAME.conf"

# Use awk to retrieve host, port from config file
HOST=`awk '/^[[:blank:]]*bind/ { print $2 }' $CONFIG_FILE | tail -n1`
PORT=`awk '/^[[:blank:]]*port/ { print $2 }' $CONFIG_FILE | tail -n1`
PASS=`awk '/^[[:blank:]]*requirepass/ { print $2 }' $CONFIG_FILE | tail -n1`
SOCK=`awk '/^[[:blank:]]*unixsocket\s/ { print $2 }' $CONFIG_FILE | tail -n1`

# Just in case, use default host, port
HOST=${HOST:-127.0.0.1}
if [ "$SERVICE_NAME" = redis ]; then
    PORT=${PORT:-6379}
else
    PORT=${PORT:-26739}
fi

# Setup additional parameters
# e.g password-protected redis instances
[ -z "$PASS"  ] || ADDITIONAL_PARAMS="-a $PASS"

# shutdown the service properly
if [ -e "$SOCK" ] ; then
    $REDIS_CLI -s $SOCK $ADDITIONAL_PARAMS shutdown
else
    $REDIS_CLI -h $HOST -p $PORT $ADDITIONAL_PARAMS shutdown
fi
#chmod +x /usr/libexec/redis-shutdown

Redis create users and set permissions

#groupadd -g 888 redis && useradd -r -u 888 -g 888 redis -s /sbin/nologin
#chown redis.redis -R /apps/redis/

Create a soft link

#ln -s /apps/redis/bin/* /usr/bin/
#ll /usr/bin/redis-*
lrwxrwxrwx 1 root root 31 Feb  9 21:34 /usr/bin/redis-benchmark -> /apps/redis/bin/redis-benchmark #redis性能测试工具
lrwxrwxrwx 1 root root 31 Feb  9 21:34 /usr/bin/redis-check-aof -> /apps/redis/bin/redis-check-aof #AOF文件检查工具
lrwxrwxrwx 1 root root 31 Feb  9 21:34 /usr/bin/redis-check-rdb -> /apps/redis/bin/redis-check-rdb #RDB文件检查工具
lrwxrwxrwx 1 root root 25 Feb  9 21:34 /usr/bin/redis-cli -> /apps/redis/bin/redis-cli #redis客户端工具
lrwxrwxrwx 1 root root 30 Feb  9 21:34 /usr/bin/redis-sentinel -> /apps/redis/bin/redis-sentinel #哨兵，软连接到server
lrwxrwxrwx 1 root root 28 Feb  9 21:34 /usr/bin/redis-server -> /apps/redis/bin/redis-server #redis服务启动命令

Change the directory path rdb file storage and set permissions

#sed -i '/^dir/s#./#/apps/redis/data#' /apps/redis/etc/redis.conf

Verify redis start

Redis resolve errors and warnings

Failed opening the RDB file dump.rdb (in server root dir /) for saving: Permission denied

Reference: https://stackoverflow.com/questions/22160753/redis-failed-opening-rdb-for-saving-permission-denied

执行systemctl stop redis命令的时候，在/var/log/messages日志中发现上面的错误，出现该错误的原因是因为关闭redis之前需要将数据保存到rdb文件中，但是因为权限原因导致报错，解决方法如下：
在redis的配置文件中指定保存rdb文件的目录，并确保相关的权限正确
#ll /apps/redis/data/ -d
drwxr-xr-x 2 redis redis 22 Feb 11 20:33 /apps/redis/data/
#vim /apps/redis/etc/redis.conf
dir /apps/redis/data

Socket Maximum Connection

Reference: https://stackoverflow.com/questions/36880321/why-redis-can-not-set-maximum-open-file

WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.

backlog参数控制的是三次握手的时候server端收到client ack确认号之后的队列值。

Memory Overcommit

WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.

0:表示内核将检查是否有足够的可用内存供应用进程使用；如果有足够的可用内存，内存申请允许；否则，内存申请失败，并把错误返回给应用进程。 
1:表示内核允许分配所有的物理内存，而不管当前的内存状态如何。 
2:表示内核允许分配超过所有物理内存和交换空间总和的内存

Since the two are related, so a resolve

#vim /etc/sysctl.conf
vm.overcommit_memory = 1
net.core.somaxconn = 1024

For these configurations take effect, you need to reload the configuration

#sysctl -p

Transparent Huge Pages

WARNING you have Transparent Huge Pages (THP) support enabled in your kernel. This will create latency and memory usage issues with Redis. To fix this issue run the command 'echo never > /sys/kernel/mm/transparent_hugepage/enabled' as root, and add it to your /etc/rc.local in order to retain the setting after a reboot. Redis must be restarted after THP is disabled.

大页内存动态分配，需要关闭让redis负责内存管理。

Provisional entry into force

echo never > /sys/kernel/mm/transparent_hugepage/enabled

To recommend a permanent solution to this problem, please follow the log and modify rc.local

#vim /etc/rc.local
if test -f /sys/kernel/mm/transparent_hugepage/enabled; then
    echo never > /sys/kernel/mm/transparent_hugepage/enabled
fi
#chmod +x /etc/rc.d/rc.local