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Redis Sentinel 启动脚本

2016年2月18日 发表评论 阅读评论 111 人阅读    

公司项目中使用到了 Redis Sentinel。以前只用过 Reids。所以,也只了解 Redis 的关闭和启动。至于 Redis Sentinel,那就抓瞎了。每次使用,都是先用现查,特别麻烦。这次在查资料时,在 Github Gist 上查到一个非常不错的启动脚本,可以非常方便地解决这个问题。分享给大家,希望对大家有所帮助。另外, 推荐大家认真阅读一下 Redis Sentinel 相关的文档。 废话完毕,上脚本:

#!/bin/bash
#
# Starts redis sentinel using start-stop-daemon
#
# D瓜哥,http://www.diguage.com/
#
# 2016-02-17

NAME=redis-sentinel
BIN=/usr/local/bin/redis-server # --1--
CONF=/usr/local/etc/sentinel.conf
SENTINEL_PID=/tmp/redis-sentinel.pid
CMD=$1

start() {
   echo "Starting $NAME ..."
   # exec 2>&1 $BIN $CONF --sentinel | logger -t sentinel & # --2--
   exec 2>&1 $BIN $CONF --sentinel &>/dev/null &
   echo $! > "${SENTINEL_PID}";
}

stop() {
   PID=`cat $SENTINEL_PID`
   echo "Stopping $NAME ($PID) ..."
   kill $PID
}

restart() {
   echo "Restarting $NAME ..."
   stop
   start
}

case "$CMD" in
   start)
     start
     ;;
   stop)
     stop
     ;;
   restart)
     restart
     ;;
   *)
     echo "Usage $0 {start|stop|restart}"
esac
  1. 使用时,请根据实际情况来修改相关命令以及参数的位置。
  2. 参考的源代码中使用的使用的是这种方式。但是,这种方式在 Mac 下,记录的 PIDlogger 命令的 PID,导致的问题时,执行关闭命令时,不能正常的杀掉 Redis Sentinel 进程。这个问题,还需要再看看有没有更好的解决方案。

这里有几点东西需要说明一下,

  • 启动时,加入了参数 &>/dev/null,导致的结果是所有的日志都直接抛掉了。不方便追查日志。

  • 在 Mac 使用 Homebrew 安装完 Reids 后,D瓜哥没有找到关于 Redis Sentinel 的相关配置。这
    里给大家提供一个模板。如下:

# port <sentinel-port>
# The port that this sentinel instance will run on
port 26379

# sentinel announce-ip <ip>
# sentinel announce-port <port>
#
# The above two configuration directives are useful in environments where,
# because of NAT, Sentinel is reachable from outside via a non-local address.
#
# When announce-ip is provided, the Sentinel will claim the specified IP address
# in HELLO messages used to gossip its presence, instead of auto-detecting the
# local address as it usually does.
#
# Similarly when announce-port is provided and is valid and non-zero, Sentinel
# will announce the specified TCP port.
#
# The two options don't need to be used together, if only announce-ip is
# provided, the Sentinel will announce the specified IP and the server port
# as specified by the "port" option. If only announce-port is provided, the
# Sentinel will announce the auto-detected local IP and the specified port.
#
# Example:
#
# sentinel announce-ip 1.2.3.4

# dir <working-directory>
# Every long running process should have a well-defined working directory.
# For Redis Sentinel to chdir to /tmp at startup is the simplest thing
# for the process to don't interfere with administrative tasks such as
# unmounting filesystems.
dir /tmp

# sentinel monitor <master-name> <ip> <redis-port> <quorum>
#
# Tells Sentinel to monitor this master, and to consider it in O_DOWN
# (Objectively Down) state only if at least <quorum> sentinels agree.
#
# Note that whatever is the ODOWN quorum, a Sentinel will require to
# be elected by the majority of the known Sentinels in order to
# start a failover, so no failover can be performed in minority.
#
# Slaves are auto-discovered, so you don't need to specify slaves in
# any way. Sentinel itself will rewrite this configuration file adding
# the slaves using additional configuration options.
# Also note that the configuration file is rewritten when a
# slave is promoted to master.
#
# Note: master name should not include special characters or spaces.
# The valid charset is A-z 0-9 and the three characters ".-_".
sentinel monitor mymaster 127.0.0.1 6379 2

# sentinel auth-pass <master-name> <password>
#
# Set the password to use to authenticate with the master and slaves.
# Useful if there is a password set in the Redis instances to monitor.
#
# Note that the master password is also used for slaves, so it is not
# possible to set a different password in masters and slaves instances
# if you want to be able to monitor these instances with Sentinel.
#
# However you can have Redis instances without the authentication enabled
# mixed with Redis instances requiring the authentication (as long as the
# password set is the same for all the instances requiring the password) as
# the AUTH command will have no effect in Redis instances with authentication
# switched off.
#
# Example:
#
# sentinel auth-pass mymaster MySUPER--secret-0123passw0rd

# sentinel down-after-milliseconds <master-name> <milliseconds>
#
# Number of milliseconds the master (or any attached slave or sentinel) should
# be unreachable (as in, not acceptable reply to PING, continuously, for the
# specified period) in order to consider it in S_DOWN state (Subjectively
# Down).
#
# Default is 30 seconds.
sentinel down-after-milliseconds mymaster 30000

# sentinel parallel-syncs <master-name> <numslaves>
#
# How many slaves we can reconfigure to point to the new slave simultaneously
# during the failover. Use a low number if you use the slaves to serve query
# to avoid that all the slaves will be unreachable at about the same
# time while performing the synchronization with the master.
sentinel parallel-syncs mymaster 1

# sentinel failover-timeout <master-name> <milliseconds>
#
# Specifies the failover timeout in milliseconds. It is used in many ways:
#
# - The time needed to re-start a failover after a previous failover was
#   already tried against the same master by a given Sentinel, is two
#   times the failover timeout.
#
# - The time needed for a slave replicating to a wrong master according
#   to a Sentinel current configuration, to be forced to replicate
#   with the right master, is exactly the failover timeout (counting since
#   the moment a Sentinel detected the misconfiguration).
#
# - The time needed to cancel a failover that is already in progress but
#   did not produced any configuration change (SLAVEOF NO ONE yet not
#   acknowledged by the promoted slave).
#
# - The maximum time a failover in progress waits for all the slaves to be
#   reconfigured as slaves of the new master. However even after this time
#   the slaves will be reconfigured by the Sentinels anyway, but not with
#   the exact parallel-syncs progression as specified.
#
# Default is 3 minutes.
sentinel failover-timeout mymaster 180000

# SCRIPTS EXECUTION
#
# sentinel notification-script and sentinel reconfig-script are used in order
# to configure scripts that are called to notify the system administrator
# or to reconfigure clients after a failover. The scripts are executed
# with the following rules for error handling:
#
# If script exits with "1" the execution is retried later (up to a maximum
# number of times currently set to 10).
#
# If script exits with "2" (or an higher value) the script execution is
# not retried.
#
# If script terminates because it receives a signal the behavior is the same
# as exit code 1.
#
# A script has a maximum running time of 60 seconds. After this limit is
# reached the script is terminated with a SIGKILL and the execution retried.

# NOTIFICATION SCRIPT
#
# sentinel notification-script <master-name> <script-path>
#
# Call the specified notification script for any sentinel event that is
# generated in the WARNING level (for instance -sdown, -odown, and so forth).
# This script should notify the system administrator via email, SMS, or any
# other messaging system, that there is something wrong with the monitored
# Redis systems.
#
# The script is called with just two arguments: the first is the event type
# and the second the event description.
#
# The script must exist and be executable in order for sentinel to start if
# this option is provided.
#
# Example:
#
# sentinel notification-script mymaster /var/redis/notify.sh

# CLIENTS RECONFIGURATION SCRIPT
#
# sentinel client-reconfig-script <master-name> <script-path>
#
# When the master changed because of a failover a script can be called in
# order to perform application-specific tasks to notify the clients that the
# configuration has changed and the master is at a different address.
#
# The following arguments are passed to the script:
#
# <master-name> <role> <state> <from-ip> <from-port> <to-ip> <to-port>
#
# <state> is currently always "failover"
# <role> is either "leader" or "observer"
#
# The arguments from-ip, from-port, to-ip, to-port are used to communicate
# the old address of the master and the new address of the elected slave
# (now a master).
#
# This script should be resistant to multiple invocations.
#
# Example:
#
# sentinel client-reconfig-script mymaster /var/redis/reconfig.sh

参考资料

  1. redis sentinel startup script

  2. Redis Sentinel Documentation – Redis



作 者: D瓜哥,http://www.diguage.com/
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