Shantanu's Blog

Corporate Consultant

June 22, 2012

 

Create Auto-scaled load balancer

Create and configure load-balancer:
elb-create-lb MyLB --availability-zones us-east-1b --listener "protocol=TCP, lb-port=3306, instance-port=3306"

elb-configure-healthcheck MyLB --target "TCP:3306" --interval 30 --timeout 2 --healthy-threshold 6 --unhealthy-threshold 2

elb-register-instances-with-lb MyLB --instances i-29184c43

Create config parameter and auto-scaling group:
as-create-launch-config MyLC --image-id ami-41d00528 --instance-type m1.small --key severalnines --group quick-start-1 

as-create-auto-scaling-group MyAutoScalingGroup --launch-configuration MyLC --availability-zones us-east-1a  --min-size 2 --max-size 5 --load-balancers MyLB

Create policies and alarms:
as-put-scaling-policy MyScaleUpPolicy --auto-scaling-group MyAutoScalingGroup  --adjustment=1 --type ChangeInCapacity  --cooldown 300
 
mon-put-metric-alarm MyHighCPUAlarm  --comparison-operator  GreaterThanThreshold  --evaluation-periods  1 --metric-name  CPUUtilization  --namespace  "AWS/EC2"  --period  600  --statistic Average --threshold  80 --alarm-actions Policy_from_previous_step --dimensions "AutoScalingGroupName=MyAutoScalingGroup"

as-put-scaling-policy MyScaleDownPolicy --auto-scaling-group MyAutoScalingGroup  --adjustment=-1 --type ChangeInCapacity  --cooldown 300

mon-put-metric-alarm MyLowCPUAlarm  --comparison-operator  LessThanThreshold --evaluation-periods  1 --metric-name  CPUUtilization --namespace  "AWS/EC2"  --period  600  --statistic Average --threshold 40 --alarm-actions Policy_from_previous_step --dimensions "AutoScalingGroupName=MyAutoScalingGroup"


Describe scaling: 

as-describe-auto-scaling-groups
as-describe-scaling-activities
as-describe-launch-configs

associate domain:
## associate and dis-associate route 53 domain to LB
elb-associate-route53-hosted-zone useast --rr-name mydb.shantanuoak.com --hosted-zone-id Z36XR238KZYP2F --weight 100

elb-disassociate-route53-hosted-zone useast --rr-name mydb.shantanuoak.com --hosted-zone-id Z36XR238KZYP2F --weight 100

Pause auto-scale:

as-suspend-processes MyAutoScalingGroup
as-resume-processes  MyAutoScalingGroup

Delete config parameter and auto scale group:
as-delete-auto-scaling-group MyAutoScalingGroup  --force-delete

as-delete-launch-config  MyLC

Replace launch config:

as-create-launch-config app-server-launch-config-2 --image-id ami-c503e8ac --instance-type c1.medium --group web

as-update-auto-scaling-group app-server-as-group-1 --launch-configuration app-server-launch-config-2

Terminate instances:
as-update-auto-scaling-group app-server-as-group-1 --min-size 0

as-terminate-instance-in-auto-scaling-group i-12345abc --decrement-desired-capacity

as-terminate-instance-in-auto-scaling-group i-12345abc --no-decrement-desired-capacity

Labels:


June 18, 2012

 

Script to install mysql

Here is the shell script that will install mysql version 5.5 on a new instance.
sh -xv /root/clean_install.sh

#!/bin/sh

# mysql data directory
my_data_dir=/data/mysql/jun19

mydate=`date '+%j%H%M%S'`

## make sure new EBS is formatted
#dmesg
#time mkfs /dev/xvdt

## Add mount point if any and mysql start command in /etc/rc.local

#/bin/mkdir -p /data
#/bin/mount /dev/xvdab /data
#/etc/init.d/iptables stop
#/etc/init.d/mysql start

## disable selinux
sed -i 's/SELINUX=enforcing/SELINUX=disabled/' /etc/sysconfig/selinux
/usr/sbin/setenforce 0
echo 0 > /selinux/enforce

## shut-down mysql if already running
mysqladmin shutdown

# remove old data directory
#rm -rf /var/lib/mysql/
rm -rf /root/download

## create required directories
# datadir
mkdir -p $my_data_dir
# pid directory
mkdir -p /var/run/mysql
# default socket directory
mkdir -p /var/lib/mysql
# download directory
mkdir /root/download
cd /root/download

wget http://files.directadmin.com/services/all/mysql/64-bit/5.5.20/MySQL-client-5.5.20-1.linux2.6.x86_64.rpm
wget http://files.directadmin.com/services/all/mysql/64-bit/5.5.20/MySQL-devel-5.5.20-1.linux2.6.x86_64.rpm
wget http://files.directadmin.com/services/all/mysql/64-bit/5.5.20/MySQL-server-5.5.20-1.linux2.6.x86_64.rpm
wget http://files.directadmin.com/services/all/mysql/64-bit/5.5.20/MySQL-shared-5.5.20-1.linux2.6.x86_64.rpm

# create my.cnf file
cat > /etc/my.cnf << heredoc

[mysqld]
datadir=$my_data_dir
socket=/var/lib/mysql/mysql.sock
user=root

max_connections=2000
max_connect_errors=18446744073709547520
open_files_limit=40000

#slave-skip-errors=1062

## logging
relay-log=slave-relay-bin
log-bin=master-bin

slow_query_log=1
slow_query_log_file=/mnt/slow.log
long_query_time=2
log-slow-slave-statements

## date %j%H%M%Sserver-id=$mydate

## network and slave needs more bandwidth
max_allowed_packet=256M

## temporary tables optimization
tmp_table_size=256M
max_heap_table_size=256M

## join queries use this buffer
read_buffer_size=32M

## Query Cache
query_cache_type = 1
query_cache_size = 200M

## Performance Tunning
key_buffer_size=1024M

## temp dir
tmpdir = /mnt/

## InnoDB optimization
innodb_buffer_pool_size=1024M
innodb_log_file_size=64M
innodb_file_per_table=1
innodb_flush_method=O_DIRECT

[mysqld_multi]
mysqld = /usr/bin/mysqld_safe
mysqladmin = /usr/bin/mysqladmin
user = multi_admin
password = multipass

[mysqld2]
socket = /tmp/mysql.sock2
port = 3307
pid-file = /mnt/data/hostname.pid2
datadir = /mnt/data/

[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysql/mysqld.pid

heredoc


# reset data-directory
mydir=`grep ^datadir /etc/my.cnf | awk -F'=' '{print $2}'`
rm -rf $mydir/*

# remove mysql
for package in `rpm -qa | grep -i mysql`
do
rpm -e $package
done

rpm -e mysql-libs-5.1.52-1.el6_0.1.x86_64

# install mysql
rpm -iUh /root/download/*

# install php
yum install -y php

# install mysql system files
mysql_install_db --datadir=$mydir

# restart mysql
/etc/init.d/mysql restart

Labels: , ,


June 15, 2012

 

Using Auto Scaling with load-balancer

We can increase / decrease instances based on a particular image that will have all the data built-in. Here are the 4 commands those we can execute to create the auto-scaling group. Auto Scaling and Load Balancing tools can be installed from the following links...

http://aws.amazon.com/developertools/2535
http://aws.amazon.com/developertools/2536

Load balancer can be easily created / disabled from the web interface. But I guess for auto-scaling we will need to install the command line tool mentioned above.

1) Create a load balancer:
elb-create-lb mysql_LoadBal --listener "1b-port=3306,instance-port=3306,protocol=TCP" --availability-zones us-east-1b

2) Create auto scaling group launch configuration:
as-create-launch-config mysql_Config --image-id ami-60da3d09 --instance-type m1.small

3) Create auto scaling group:
as-create-auto-scaling-group mysql_AutoScale --launch-configuration mysql_Config --availability-zones us-east-1b --min-size 1 --max-size 5 load-balancers mysql_LoadBal

4) Create Trigger:
as-create-or-update-trigger mysql_Trigger1 --auto-scaling-group mysql_AutoScale --namespace "AWS/EC2" --measure CPUUtilization --statistic Average --dimensions "AutoScalingGroupName=mysql_AutoScale" --units "Percent" --period 60 --lower-threshold 30 --upper-threshold 70 --lower-breach-increment"=-1" --upper-breach-increment "1" --breach-duration 120

When average CPU utilization in the group exceeds 70% over a two-minute interval, increase instances up-to maximum of 5. When load falls below 30% reduce the number of instances but keep at-least 1 instance running.

To check how it is working:
as-describe-scaling-activities mysql_AutoScale
_____

i) In order to disable auto-scaling We will first have to remove the trigger:
as-delete-trigger mysql_Trigger1 --auto-scaling-group mysql_AutoScale

ii) Set minimum and maximum size of the group to 0 to force all its instances to terminate:
as-update-auto-scaling-group mysql_AutoScale --min-size 0 --max-size 0

iii) Remove auto-scaling group:
as-delete-auto-scaling-group mysql_AutoScale

iV) Remove load balancer:
elb-delete-lb mysql_LoadBal

Labels:


 

EC2 Instance Metadata

Each EC2 instance can access run-time data about itself by making HTTP requests to the special address 169.254.169.254

wget -q http://169.254.169.254/latest/meta-data/instance-id

cat instance-id
i-d830dfb0

You can also supply your own metadata when you launch an EC2 instance. This data is called "User Data". For e.g.

wget -q http://169.254.169.254/latest/user-data
cat user-data
Role=master_db,Size=small,Name=Production,Input=Queue1

You can have your custom AMI treat the user metadata as the URL of the script to be run when the instance starts.

Labels:


 

EBS Raid


We can glue the EBS volumes together into a RAID.

mdadm --create /dev/md0 --level 0 --metadata=1.1 --raid-devices 2 /dev/sdh1 /dev/sdh2

Add the following line to /etc/mdadm.conf (creating if necessary)

DEVICES /dev/sdh1 /dev/sdh2

Run the following command to add additional configuration information to the file:

mdadm --detail --scan >> /etc/mdadm.conf

At this point the RAID volume (/dev/md0) has been created. It encapsulates the 2 volumes.

Create a file system:

mkfs /dev/md0

create a mount point and mount the volume on it:

mkdir /data
mount /dev/md0 /data

Labels:


June 12, 2012

 

Check return code

While using "system" function to execute linux commands within PHP, we can use a variable to store the return value. We will continue only if the return value is 0 (success) or exit the script.

system("mysqldump -uroot db1 --ignore-table=db1.tbl_1 --ignore-table=db1.tbl_2 > /root/db1.sql", $retval);

if ($retval != '0') {
  exit ("dump db1.sql command failed");
}

June 08, 2012

 

Restarting slave

I have always ignored the following warning.

[Warning] Neither --relay-log nor --relay-log-index were used; so replication may break when this MySQL server acts as a slave and has his hostname changed!! Please use '--relay-log=slave-usw-relay-bin' to avoid this problem.

This made a big difference when I changed the AWS EBS and attached it to a new instance. Since the new instance had a new IP address, the relay-log file name was inconsistent. Therefore we must always specify log-bin and relay-log parameters in my.cnf

log-bin=usw-slave-bin
realy-log=usw-slave-relay-bin
_____

It is possible to recover slave if it has Failed to open the relay log. It is possible that MySQL saved it's relay logs in /var/run by default, which gets cleared out on boot.

To fix this, there are 2 ways.

you need to change the location MySQL uses for the logging by adding the following line to the [mysqld] section of /etc/my.cnf

relay-log = /var/lib/mysql/relay-bin

Then edit /var/lib/mysql/relay-log.info to point to the first new relay log (leaving the master information the same.

/var/lib/mysql/relay-bin.000001
1
mysql-bin.12345
123456789

Start the slave. Or if you already have the slave status at the time of stopping the slave. Note the following 2 parameters.

       Relay_Master_Log_File: mis-bin.000710
          Exec_Master_Log_Pos: 461352141

And then reset slave and start the replication by using the statement "CHANGE MASTER TO ..."


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