动态增删节点
某些情况下,我们需要根据实际的业务情况,对已经在运行的集群进行动态的添加或删除节点,那我们就需要进行以下操作。
1.增加主节点
添加方式一:cluster meet
使用 cluster meet ip:port 命令就可以把一个节点加入到集群中,执行命令如下:
127.0.0.1:30001> cluster meet 127.0.0.1 30007 OK 127.0.0.1:30001> cluster nodes dc0702625743c48c75ea935c87813c4060547cef 127.0.0.1:30006@40006 slave 3da35c40c43b457a113b539259f17e7ed616d13d 0 1585142916000 6 connected df0190853a53d8e078205d0e2fa56046f20362a7 127.0.0.1:30007@40007 master - 0 1585142917740 0 connected f5958382af41d4e1f5b0217c1413fe19f390b55f 127.0.0.1:30003@40003 master - 0 1585142916738 3 connected 10923-16383 3da35c40c43b457a113b539259f17e7ed616d13d 127.0.0.1:30002@40002 master - 0 1585142913000 2 connected 5461-10922 abec9f98f9c01208ba77346959bc35e8e274b6a3 127.0.0.1:30005@40005 slave 887397e6fefe8ad19ea7569e99f5eb8a803e3785 0 1585142917000 5 connected 887397e6fefe8ad19ea7569e99f5eb8a803e3785 127.0.0.1:30001@40001 myself,master - 0 1585142915000 1 connected 0-5460 1a324d828430f61be6eaca7eb2a90728dd5049de 127.0.0.1:30004@40004 slave f5958382af41d4e1f5b0217c1413fe19f390b55f 0 1585142916000 4 connected
可以看出端口为 30007 的节点并加入到集群中,并设置成了主节点。
添加方式二:add-node
使用 redis-cli --cluster add-node 添加节点ip:port 集群某节点ip:port 也可以把一个节点添加到集群中,执行命令如下:
$ redis-cli --cluster add-node 127.0.0.1:30008 127.0.0.1:30001 >>> Adding node 127.0.0.1:30008 to cluster 127.0.0.1:30001 >>> Performing Cluster Check (using node 127.0.0.1:30001) M: 887397e6fefe8ad19ea7569e99f5eb8a803e3785 127.0.0.1:30001 slots:[0-5460] (5461 slots) master 1 additional replica(s) S: dc0702625743c48c75ea935c87813c4060547cef 127.0.0.1:30006 slots: (0 slots) slave replicates 3da35c40c43b457a113b539259f17e7ed616d13d M: df0190853a53d8e078205d0e2fa56046f20362a7 127.0.0.1:30007 slots: (0 slots) master M: f5958382af41d4e1f5b0217c1413fe19f390b55f 127.0.0.1:30003 slots:[10923-16383] (5461 slots) master 1 additional replica(s) M: 1d09d26fd755298709efe60278457eaa09cefc26 127.0.0.1:30008 slots: (0 slots) master M: 3da35c40c43b457a113b539259f17e7ed616d13d 127.0.0.1:30002 slots:[5461-10922] (5462 slots) master 1 additional replica(s) S: abec9f98f9c01208ba77346959bc35e8e274b6a3 127.0.0.1:30005 slots: (0 slots) slave replicates 887397e6fefe8ad19ea7569e99f5eb8a803e3785 S: 1a324d828430f61be6eaca7eb2a90728dd5049de 127.0.0.1:30004 slots: (0 slots) slave replicates f5958382af41d4e1f5b0217c1413fe19f390b55f [OK] All nodes agree about slots configuration. >>> Check for open slots... >>> Check slots coverage... [OK] All 16384 slots covered. [ERR] Node 127.0.0.1:30008 is not empty. Either the node already knows other nodes (check with CLUSTER NODES) or contains some key in database 0.
从以上结果可以看出 30008 节点也被设置成了主节点。
2.添加从节点
使用 cluster replicate nodeId 命令就可以把当前节点设置为目标节点的从节点,执行命令如下:
127.0.0.1:30008> cluster replicate df0190853a53d8e078205d0e2fa56046f20362a7 OK 127.0.0.1:30008> cluster nodes df0190853a53d8e078205d0e2fa56046f20362a7 127.0.0.1:30007@40007 master - 0 1585147827000 0 connected abec9f98f9c01208ba77346959bc35e8e274b6a3 127.0.0.1:30005@40005 slave 887397e6fefe8ad19ea7569e99f5eb8a803e3785 0 1585147827000 1 connected 1a324d828430f61be6eaca7eb2a90728dd5049de 127.0.0.1:30004@40004 slave f5958382af41d4e1f5b0217c1413fe19f390b55f 0 1585147823000 3 connected 887397e6fefe8ad19ea7569e99f5eb8a803e3785 127.0.0.1:30001@40001 master - 0 1585147826000 1 connected 0-5460 dc0702625743c48c75ea935c87813c4060547cef 127.0.0.1:30006@40006 slave 3da35c40c43b457a113b539259f17e7ed616d13d 0 1585147826930 2 connected f5958382af41d4e1f5b0217c1413fe19f390b55f 127.0.0.1:30003@40003 master - 0 1585147826000 3 connected 10923-16383 1d09d26fd755298709efe60278457eaa09cefc26 127.0.0.1:30008@40008 myself,slave df0190853a53d8e078205d0e2fa56046f20362a7 0 1585147823000 7 connected 3da35c40c43b457a113b539259f17e7ed616d13d 127.0.0.1:30002@40002 master - 0 1585147827933 2 connected 5461-10922
可以看出 30008 已经变为 30007 的从节点了。
3.删除节点
使用 cluster forget nodeId 命令就可以把一个节点从集群中移除。此命令和 meet 命令不同的时,删除节点需要是使用节点的 Id 进行删除,可以通过 cluster nodes 命令查看所有节点的 Id 信息,其中每一行的最前面的 40 位字母和数组的组合就是该节点的 Id,如下图所示:
执行命令如下:
127.0.0.1:30001> cluster forget df0190853a53d8e078205d0e2fa56046f20362a7 OK
此时我们使用 cluster nodes
命令查看集群的所有节点信息:
127.0.0.1:30001> cluster nodes dc0702625743c48c75ea935c87813c4060547cef 127.0.0.1:30006@40006 slave 3da35c40c43b457a113b539259f17e7ed616d13d 0 1585143789940 6 connected f5958382af41d4e1f5b0217c1413fe19f390b55f 127.0.0.1:30003@40003 master - 0 1585143791000 3 connected 10923-16383 3da35c40c43b457a113b539259f17e7ed616d13d 127.0.0.1:30002@40002 master - 0 1585143789000 2 connected 5461-10922 abec9f98f9c01208ba77346959bc35e8e274b6a3 127.0.0.1:30005@40005 slave 887397e6fefe8ad19ea7569e99f5eb8a803e3785 0 1585143789000 5 connected 887397e6fefe8ad19ea7569e99f5eb8a803e3785 127.0.0.1:30001@40001 myself,master - 0 1585143786000 1 connected 0-5460 1a324d828430f61be6eaca7eb2a90728dd5049de 127.0.0.1:30004@40004 slave f5958382af41d4e1f5b0217c1413fe19f390b55f 0 1585143791945 4 connected
可以看出之前的端口为 30007 的节点已经被我们成功的移除了。
小结
本文讲了 Redis 集群的两种搭建方式:create-cluster start 和 cluster create,前一种方式虽然速度比较快,但它只能创建数量固定的主从节点,并且所有节点都在同一台服务器上,因此只能用于测试环境。我们还讲了 Redis 集群动态添加主、从节点和删除任意节点的功能。
希望本文对你有帮助,动手实践起来吧~