rcm.cr

Redis Cluster Manager in Crystal

Programming language: Crystal

License: MIT License

Tags: Environment Management    

Latest version: v0.7.7

README

rcm.cr

Redis Cluster Manager

Features

• manage: creates cluster easily and provides many commands
• monitor: watches nodes periodically on cli
• httpd: provides http api service to redis

Why not use redis-cli?

• BUG: cluster with unixsock causes infinite loop.
  • https://github.com/antirez/redis/pull/3709

Why not use redis-trib.rb?

• That has ugly syntax. (why SHA1?)
• That doesn't support AUTH and manual F/O and ....
• That depends ruby and redis-cli.

	redis-trib	rcm
Replicate	redis-cli -p 7004 cluster replicate 34f256...	rcm -p 7004 replicate :7001
Manual F/O	N/A	rcm -p 7004 failover; rcm -p 7001 failback
Create with AUTH	N/A	rcm -a XXX create ...
Migrate	(slow : send N-times commands for N keys)	(bulk : send like 10000 keys in 1 command )
Portability	docker run ruby:2.3 ruby redis-trib ...	rcm ...

If you don't mind these points at all, I recommend you to use redis-trib.

Installation

Static Binary is ready for x86_64 linux

• https://github.com/maiha/rcm.cr/releases

Compile from source

• tested on crystal-0.34.0

% make
% cp bin/rcm /usr/local/bin/

Usage (information features)

schema

• show cluster schema about node dependencies

% rcm -p 7000 schema
[0-3276     ] 192.168.0.1:7001 192.168.0.2:7002 192.168.0.3:7003
[3277-6553  ] 192.168.0.2:7001 192.168.0.3:7002 192.168.0.4:7003
[6554-9830  ] 192.168.0.3:7001 192.168.0.4:7002 192.168.0.5:7003
[9831-13107 ] 192.168.0.4:7001 192.168.0.1:7003 192.168.0.5:7002
[13108-16383] 192.168.0.5:7001 192.168.0.1:7002 192.168.0.2:7003

• It can be used as continuous test for node dependencies.
• For example, we can easily alert failover or node down by crontab.

% rcm -p 7000 schema > /data/redis-cluster-7000.schema

*/5 * * * * diff /data/redis-cluster-7000.schema $(rcm -p 7000 schema)

status

• summarize nodes status in the cluster

% rcm -p 7000 status
[0-3000     ] master(127.0.0.1:7012) with 2 slaves
[3001-6000  ] master(127.0.0.1:7001) with 1 slaves
[6001-9000  ] master(127.0.0.1:7002) with 1 slaves
[9001-12000 ] master(127.0.0.1:7003) with 1 slaves
[12001-16383] master(127.0.0.1:7004) with 1 slaves

% rcm -p 7000 status -v
[0-3000     ] M(127.0.0.1:7012) S(127.0.0.1:7000) S(127.0.0.1:7014)
[3001-6000  ] M(127.0.0.1:7001) S(127.0.0.1:7006) S(127.0.0.1:7008) S(127.0.0.1:7011)
[6001-9000  ] M(127.0.0.1:7002) S(127.0.0.1:7007)
[9001-12000 ] M(127.0.0.1:7003) S(127.0.0.1:7013)
[12001-16383] M(127.0.0.1:7004) S(127.0.0.1:7009)

nodes

• provides human-friendly output rather than redis-cli

% rcm -p 7001 nodes
b98ca1 [127.0.0.1:7001](0)  [0-5000     ] master(*)
835bea [127.0.0.1:7004](0)    +slave(*) of 127.0.0.1:7001
8a3c07 [127.0.0.1:7002](0)  [5001-10000 ] master(*)
0d0c75 [127.0.0.1:7005](0)    +slave(*) of 127.0.0.1:7002
33d324 [127.0.0.1:7003](0)  [10001-16383] master(*)
4a4da6 [127.0.0.1:7006](0)    +slave(*) of 127.0.0.1:7003
2581a1 [127.0.0.1:7007](0)  standalone master(*)
[OK] All 16384 slots are covered by 3 masters and 3 slaves.
[OK] All slots are available with 2 replication factor(s).

• NOTICE: This sends INFO keyspace to all nodes.

info

• summarize INFO for each nodes

% rcm -p 7001 info
edb22e [127.0.0.1:7001]  ver(3.2.0), cnt(7633), mem(2.27M;noev;0%), days(0)
f0da61 [127.0.0.1:7002]  ver(3.2.0), cnt(8751), mem(2.61M;noev;0%), days(0)

• arg can be used to select a specific line like grep arg INFO

% rcm -p 7001 info role,cnt,day
edb22e [127.0.0.1:7001]  role(master), cnt(7633), days(0)
f0da61 [127.0.0.1:7002]  role(master), cnt(8751), days(0)

• reserved field names for easy access

  • v , ver , version : delegate to redis_version
  • m , mem , memory : summarize used_memory_human , maxmemory_policy and maxmemory_human
  • cnt, count : extract db0:keys=(\d+)
  • d, day : delegate to uptime_in_days

• NOTICE: This sends INFO to all nodes.

slot : calculate keyslot values

% rcm slot foo
12182

% rcm slot foo bar -v
foo     12182
bar     5061

% rcm slot foo "{foo}.bar" -v
foo     12182
{foo}.bar       12182

Usage (cluster feature)

• create : ADDSLOTS, MEET, REPLICATE
• join : just MEET and wait all nodes to join the cluster
• forget : remove the node from cluster

create : create cluster automatically

% rcm create 192.168.0.1:7001 192.168.0.2:7002 -n  # dryrun
% rcm create 192.168.0.1:7001 192.168.0.2:7002
% rcm create --masters 5 192.168.0.1:7001 192.168.0.2:7002 ...

• master size can be set by "--masters NUM"
• otherwise hosts count is used in default

join : create cluster autmatically without addslots and replicate

% rcm join 192.168.0.1:7001 192.168.0.2:7002 ...

create cluster manually

% rcm -p 7001 addslots -5000       # means 0-5000
% rcm -p 7002 addslots 5001-10000
% rcm -p 7003 addslots 10001-      # means 10001..16383

% rcm -p 7002 meet 127.0.0.1:7001
% rcm -p 7003 meet 127.0.0.1:7001

forget : send "CLUSTER FORGET" to all nodes except the given node

For example, assume that a node (port :7004) is broken where rcm nodes prints like this.

a830a2 [192.168.0.1:7003](177877)    +slave(*) of 192.168.0.1:7002
3008b0 [127.0.0.1:0]   (    -1)  standalone master,fail,noaddr(!)

Here, we want to remove the node that was running on port:7004 (sha1: 3008b0...).

% rcm -p 7003 forget 3008b0

Usage (replication features)

start replication

• meet and replicate (ex. make :7004 slaveof :7001)

% rcm -p 7004 meet 127.0.0.1:7001       # same as "meet :7001" for localhost
% rcm -p 7004 replicate 127.0.0.1:7001  # same as "replicate :7001" for localhost

switch master and slave

native redis cluster protocol

• failover (slave feature) : becomes master with agreement
• takeover (slave feature) : becomes master without agreement

rcm methods for graceful failover

• wait : wait for replication to finish
• fail (master feature) : becomes slave and wait a new master is up (linked)
• failback (slave feature) : becomes master and wait data sync is finished

% rcm -p 7001 fail      # 7001: master -> slave (now we can stop 7001 gracefully)
% rcm -p 7001 failover  # 7001: slave -> master (now we can stop slaves gracefully)

• Sequentially applying fail and failover means NOP

advise

• In biased replications, nodes and advise advise a command to fix it. ``` % rcm -p 7001 nodes ... [OK] All slots are available with 2+ replication factor(s). advise: This can provide better replication. (rf of '127.0.0.1:7017': 2 -> 3) rcm -h '127.0.0.1' -p 7011 REPLICATE 127.0.0.1:7017

% rcm -h '127.0.0.1' -p 7011 REPLICATE 127.0.0.1:7017 REPLICATE 127.0.0.1:7017 OK

% rcm -p 7001 nodes ... [OK] All slots are available with 3 replication factor(s).

- `advise --yes` is suit for batch.

NOP when replication is well balanced

% rcm -p 7001 advise --yes

replicate command is executed automatically when unblanaced

% rcm -p 7001 advise --yes 2016-06-23 21:21:49 +0900: BetterReplication: rf of '127.0.0.1:7016': 2 -> 3 rcm -h '127.0.0.1' -p 7012 REPLICATE 127.0.0.1:7016 REPLICATE 127.0.0.1:7016 OK

## Usage (utility features)

### watch (experimental)

- provides continual monitoring using curses
- ex) `rcm -p 7001 watch`

2016-06-27 09:54:36 +0900

[0-5000 ] 127.0.0.1:7001(5001) .........++.................. +slave 127.0.0.1:7004(5001) .........++.................. [5001-10000 ] 127.0.0.1:7005(5000) ..........++................. +slave 127.0.0.1:7002(5000) ..........++.....EEEEEEE..... [10001-16383] 127.0.0.1:7003(6384) ...........++................ +slave 127.0.0.1:7006(6384) .......EEEEEEE.+............. ( no slots ) 127.0.0.1:7007(0) .............................

### import

- (experimental) This is too slow deu to step import by one by
- works with using `SET`

```shell
% rcm -p 7001 import foo.tsv

migrate

• migrate data from given redis server to this cluster
• options: --count for SCAN
• options: --copy, --replace
  • see: https://redis.io/commands/migrate

For example, we can migrate from host1:6379 with pass1 to new cluseter cluster-broker1:7001 by following command.

% rcm -u pass1@host1:6379 migrate --to cluster-broker1:7001 --replace

Usage (httpd : provides web interfaces)

• provides REST API that accepts "/CMD/args1/arg2/..." for redis

% rcm -p 7001 httpd :3000
% curl 127.0.0.1:3000/SET/hello/world  # same as "SET hello world"
OK
% curl 127.0.0.1:3000/GET/hello        # same as "GET hello"
world

# When redis requires AUTH(xxx), httpd automatically provides basic auth with "redis:xxx".
% rcm -u xxx@:7001 httpd :3000
% curl -u redis:xxx 127.0.0.1:3000/INCR/cnt
1

# The username of basic auth can be overwriten by listen arg like 'admin@'.
% rcm -u xxx@:7001 httpd adm[email protected]:3000
% curl -u admin:xxx 127.0.0.1:3000/INCR/cnt
2

• output format is one of "txt", "raw", "resp", "json"

% curl 127.0.0.1:3000/GET/hello.txt  # => "world\n"
% curl 127.0.0.1:3000/GET/hello.raw  # => world
% curl 127.0.0.1:3000/GET/hello.resp # => $5\r\nworld\r\n
% curl 127.0.0.1:3000/GET/hello.json # => {"get":"world"}

Usage (redis commands)

• All other args will be passed to redis as is.
• In this case, standard or clustered redis is automatically guessed.

(standard redis is running on 6379)
% rcm config get maxmemory
["maxmemory", "10000000"]

(clustered redis is running on 7001,7002,... with AUTH `dev`)
% rcm -u dev@:7002 config get maxmemory
["maxmemory", "10000000"]

Connecting to nodes

various ways to connect to nodes

• -h <host>
• -p <port>
• -a <password>
• -u <uri>

% rcm ...                 # "127.0.0.1:6379" (default)
% rcm -h 192.168.0.1 ...  # "192.168.0.1:6379"
% rcm -p 7001 ...         # "127.0.0.1:7001"
% rcm -p 7001 -a xyz ...  # "127.0.0.1:7001" with AUTH "xyz"
% rcm -u redis://foo ...  # "foo:6379" (strict uri form)
% rcm -u foo ...          # "foo:6379" (scheme is optional)
% rcm -u :7001 ...        # "127.0.0.1:7001"
% rcm -u foo:7001 ...     # "foo:7001"
% rcm -u xyz@foo:7001 ... # "foo:7001" with AUTH "xyz"
% rcm -u xyz@foo:7001 ... # "foo:7001" with AUTH "xyz"
% rcm -u xyz@ ...         # "127.0.0.1:6379" with AUTH "xyz"
% rcm -u xyz@:7001 ...    # "127.0.0.1:7001" with AUTH "xyz"
% rcm -u xyz@foo ...      # "foo:6379" with AUTH "xyz"

Usage (as a replace of redis-cli)

• --raw option is available.

% rcm --raw get foo > foo.bin

Usage (as a crystal library)

see examples/*.cr

But, you'd better use redis-cluster.cr rather than this for library.

• https://github.com/maiha/redis-cluster.cr

TODO

• [ ] Dryrun
• [ ] Check
  • [x] Nodes health check
  • [x] Slots coverage check
  • [x] detect orphaned master
  • [x] detect orphaned slave
• [ ] Schema
  • [x] Dump cluster schema
  • [ ] Reset node dependencies by schema file
• [ ] Advise
  • [x] Rebalance nodes
  • [ ] Rebalance slots
• [ ] Utils
  • [x] Create cluster
  • [x] Rebalance nodes
  • [ ] Rebalance slots
  • [ ] Bulkinsert on import
  • [x] Watch monitoring
  • [x] Graceful failover
• [x] Web UI
  • [x] Command Api
  • [x] Cluster Info
• [ ] Debug
  • [ ] Scan slots

Development

• for ubuntu

apt-get install libncursesw5-dev
apt-get install libgpm-dev        # needs only for static link

Contributing

1. Fork it ( https://github.com/maiha/rcm.cr/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Contributors

• maiha maiha - creator, maintainer