Load Balancing MySQL with HAProxy - Slides

Confidential
Load Balancing with HAProxy and MySQL
January 28, 2015
Alex Yu 
alex@severalnines.com

Copyright Severalnines AB
Webinar Housekeeping
!This webinar is being recorded
!A link to the recording & slides will be posted on severalnines.com
!We welcome questions: enter questions into the chat box and we
will respond at the end of the presentation
!Think of something later?
! Email Severalnines at info@severalnines.com
2

Agenda
!What Is HAProxy?
!SQL Load Balancing with HAProxy
! Failure detection with MySQL
!Fault Tolerance with HAProxy
! Active/Passive setup
!Deployment Scenarios
! MySQL Cluster, Galera Cluster and MySQL Replication
!Load Balancing Alternatives
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Why Load Balance?
!Optimising server utilisation
! Queuing and throttling
!Maximise availability
! No SPOF
!Maximise throughput
! Distribute workload across a set of servers
!Scalability
! Site traffic grows
! Add DB servers to provide more throughput
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LB
DB DB DB …

!Reliable High Performance TCP/HTTP Load Balancer
! v1.5 stable released June 2014
! Native SSL support, IPv6, full HTTP keepalive, HTTP Compression …
! v1.4 most deployed and stable version, released Feb 2010
! client-side keep alive, TCP speedups, source base stickiness …
! Single Process Event-Driven. Can easily saturate 10Gb link with a single instance
! 108 000 session/s, http://www.haproxy.org/10g.html (2009)
!Reverse Proxy
! load balancing, scaling out, failover (health checks)
!High traffic sites like
! reddit, DISQUS, GitHub, Imgur, StackOverflow/Server Fault, Instagram …
HAProxy?
5

SQL Load Balancing for MySQL
!Configuration file
! Sections; global, defaults, frontend, backend, listen
! /etc/haproxy/haproxy.cfg
!Global (process wide)
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MySQL
[WSREP]
Galera Replication (Synchronous)
LB
MySQL
[WSREP]
MySQL
[WSREP]
R/W R/W R/W
Client Client Client
global 
log 127.0.0.1 local0
pidfile /var/run/haproxy.pid
daemon
user nobody
group nobody
stats socket /tmp/haproxy.socket …
node HAProxy_1
description HAProxy 1
maxconn 40000
spread-checks 3
quiet

SQL Load Balancing for MySQL (cont.)
!defaults
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MySQL
[WSREP]
LB
MySQL
[WSREP]
MySQL
[WSREP]
R/W R/W R/W
defaults
log global
mode tcp
maxconn 40000
option dontlognull
option tcp-smart-accept
option tcp-smart-connect
option redispatch
retries 3
timeout queue 3500ms
timeout connect 3500ms
timeout client 120s
timeout server 120s

!listen (frontend + backend)
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listen s9s1_33306_defaul_LB
mode tcp 
bind *:33306
timeout client 60s
timeout server 60s
balance leastconn
option httpchk
default-server port 9200 inter 2s downinter 5s rise 3 fall 2 slowstart 60s maxconn 256
maxqueue 128 weight 100
server db1 10.0.3.70:3306 check

!listen (stats ui)
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userlist STATSUSERS
group admin users admin
user admin insecure-password admin
listen admin_page 0.0.0.0:9600
mode http
stats enable
stats refresh 60s
stats uri /
acl AuthOkay_ReadOnly http_auth(STATSUSERS)
acl AuthOkay_Admin http_auth_group(STATSUSERS) admin
stats http-request auth realm admin_page unless AuthOkay_ReadOnly

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!Session rate
! number of new connections per second
!Sessions
! current number of sessions/connections
!LastChk
! health check
!Wght
! server weight

MySQL Health Checks
11
!Built-in MySQL health check
! option mysql-check user <username>
! Sends two MySQL packages
! Authentication and Quit
! No errors unless MySQL server is down
!Complete HTTP Request
! option httpchk
! Response: HTTP/1.1 200 OK
! Check Host and/or MySQL server state
! Galera Node State
MySQL
[WSREP]
LB
MySQL
[WSREP]
MySQL
[WSREP]
R/W R/W R/W

MySQL Health Checks (cont.)
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!Galera Node
! Check 1: Get node state
! SYNCED or DONOR
! Check 2: If Node is a “DONOR”
! Get the SST method
! xtrabackup
! Return “200 OK”
! rsync or mysqldump
! Return “503 Service Unavailable” Galera Node State

MySQL Health Checks (cont.)
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!xinetd service
! mysqlchk.sh (shell script)
! spams syslog by default
! log_on_success =
#/etc/xinetd.d/mysqlchk
# default: on
# description: mysqlchk
service mysqlchk
{
flags = REUSE
socket_type = stream
port = 9200
wait = no
user = nobody
server = /usr/local/bin/mysqlchk.sh
log_on_failure += USERID
disable = no
#only_from = 0.0.0.0/0
per_source = UNLIMITED
}

Network Tuning
!TCP tuning
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#/etc/sysctl.conf
net.ipv4.ip_nonlocal_bind=1
net.ipv4.tcp_tw_reuse=1 # reuse TIME-WAIT sockets
net.ipv4.ip_local_port_range=1024 65023 # increase max num of ports
net.ipv4.tcp_max_syn_backlog=40000 #Increase the number of outstanding syn requests
net.ipv4.tcp_max_tw_buckets=400000 # Maximal number of timewait sockets
net.ipv4.tcp_max_orphans=60000
net.ipv4.tcp_max_syn_backlog=40000 # TCP SYN Flood Protection
net.ipv4.tcp_synack_retries=3 # TCP SYN Flood Protection
net.core.somaxconn=40000 # burst connection rate
net.ipv4.tcp_fin_timeout=5 # how long to keep sockets in FIN-WAIT-2

Fault Tolerance for HAProxy
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Client
HAProxy 1
MySQL  MySQL  MySQL 
IP: 10.10.10.20

Fault Tolerance for HAProxy (cont.)
!Active/Passive IP failover
! keepalived
! VRRP protocol provides router/IP failover
!VIP, “floating IP”: 10.10.0.10
! net.ipv4.ip_nonlocal_bind=1
!Master - HAProxy 1
! IP: 10.10.10.20
!Backup - HAProxy 2
! IP: 10.10.10.30
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Fault Tolerance for HAProxy (cont.)
!keepalived configuration file
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#/etc/keepalived/keepalived.conf
vrrp_script chk_haproxy {
script "killall -0 haproxy" # verify the pid existence
interval 2 # check every 2 seconds
weight 2 # adjust priority by this weight
}
vrrp_instance VI_1 {
interface eth0
state MASTER
virtual_router_id 51 # ID for this route
priority 101 # 101 on master 
# 100 on backup
virtual_ipaddress {
10.10.0.10 # the virtual IP
}
track_script {
chk_haproxy
}
}

ClusterControl HAProxy + Keepalived (cont.)
!Deployment and configuration automated from ClusterControl
18

ClusterControl HAProxy + Keepalived (cont.)
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Deployment Scenarios
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!MySQL Cluster / NDB Engine
! Active/Active, Shared nothing architecture
! SQL, Data and MGMT Nodes
! HAProxy co-located with MGMT Nodes
! MGMT is a light weight process
! Re-use “idle” servers
! Connections originate from HAProxy server
! Additional latency
! App Server <-> HAProxy <-> SQL Node <-> Data Node
NDB Data
Node
NDB Data
Node
(MGMT)
HAProxy
(MGMT)
HAProxy
SQL Node 
MySQL
Server
SQL Node 
MySQL
Server

Deployment Scenarios (cont.)
21
NDB Data
Node
NDB Data
Node
!MySQL Cluster / NDB Engine
! Active/Active, Shared nothing architecture
! SQL, Data and MGMT Nodes
! HAProxy co-located with App servers
! No extra latency
! Extra load on app servers
! Health check loads on SQL nodes from all LBs
! Alt: MySQL Connector/J’s JDBC driver
! jdbc:mysql:loadbalance://host-1,host-2,…host-n/database?
loadBalanceBlacklistTimeout=5000
! Config changes propagate to all app servers
(App)
HAProxy
(App)
HAProxy
SQL Node 
MySQL
Server
SQL Node 
MySQL
Server

22
MySQL Slave
MySQL
Master
!MySQL Replication Master/Slave
! 1 Master for Writes
! N Slaves for Reads
! Separate front and backends configs for Master and Slaves
!ex: backend configuration for Slaves
HAProxy
MySQL Slave
MySQL Slave
Writes
Reads
frontend front_reads
mode tcp
bind 192.168.100.110:3316
default_backend cluster_reads
 
backend cluster_reads
mode tcp
balance roundrobin
server Slave1 10.10.10.30:3306 check
server Slave2 10.10.10.40:3306 check

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!Galera Cluster
! Synchronous Replication, Read & Write to any Node
! Cluster wide optimistic locking
! Higher probability for “deadlocks”
! Pessimistic locking on the Node
! Ex: sequence table, “hotspot” tables
! Write to one node, Read/Write split
! Application: Retry deadlock errors
MySQL
[WSREP]
LB
MySQL
[WSREP]
MySQL
[WSREP]
R/W R/W R/W

Alternatives
!MySQL’s Connector/J JDBC driver
!jdbc:mysql:loadbalance://host-1,host-2,…
!PHP mysqlnd
! http://www.php.net/manual/en/intro.mysqlnd-ms.php
!Oracle’s MySQL Proxy 0.84
! http://dev.mysql.com/downloads/mysql-proxy/
!SkySQL’s MaxScale 1.0.0. beta
! https://github.com/skysql/MaxScale
!ProxySQL
! https://github.com/renecannao/proxysql
!Pen 0.24.0
! http://morestuff.siag.nu/category/pen/
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Thank You!
!Tutorial – MySQL Load Balancing with HAProxy
! http://www.severalnines.com/resources/clustercontrol-mysql-haproxy-load-
balancing-tutorial
!Severalnines Blog and Webinars
! www.severalnines.com/blog
! http://www.severalnines.com/resources/webinars
!More Questions? Contact us at:
! info@severalnines.com
25

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