System Administration

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Centos AMI on Amazon EC2 – How To Resize The Disk

When using the official CentOS Linux AMI on EC2, it comes (currently) with only an 8GB partition.  Want to resize that?  Here is how…

First make sure you start a small (t2.micro or similar) instance to do this work with.  It should be based on the Amazon Linux AMI.  You should have root access to it.  Let’s call it “fix-the-disk-instance”.

  1. Stop the NEW instance
    1. Go to EC2 > Instances
    2. Select the Instance
    3. Make sure the Instance has a name that makes sense (e.g. snap.appcove.net)
    4. Click “Actions” > “Instance State” > Stop
  2. Detach the block device
    1. Go to EC2 > Volumes
    2. Find the volume by looking under Attachment Information for the instance name (e.g. snap.appcove.net)
    3. Select the volume
    4. Click “Actions” > “Detach Volume”
  3. Attach the block device to “fix-the-disk-instance”
    1. Go to EC2 > Volumes
    2. Find the volume by looking under Attachment Information for the instance name (e.g. snap.appcove.net)
    3. Select the volume
    4. Click “Actions” > “Attach Volume”
    5. Attach it to “fix-the-disk-instance” so we can fix it up
  4. Start “fix-the-disk-instance” and login
    1. Go to EC2 > Volumes
    2. Select the Instance “fix-the-disk-instance”
    3. Click “Actions” > “Instance State” > Start
    4. Wait for it to start
    5. SSH into it and escalate to root
  5. Run `parted` command and print list
    1. As root, run the following command: parted
    2. Type the following command: print all<enter>
    3. Find your disk in the output and note the path (e.g. /dev/xvdf)
    4. Quit the program by typing: quit<enter>
  6. Resize the partition:
    1. Run fdisk on the device path found above (e.g. fdisk /dev/xvdf)
    2. List the partitions
      1. Type: p<enter>
      2. Take note of the “Start” column (e.g. 2048)
    3. Delete the partition
      1. Type: d<enter>
    4. Create a new one by typing:
      1. n (for new)
      2. p (for primary)
      3. 1 (for first partition)
      4. Type first sector the same as the Start column above (e.g. 2048)
      5. Last sector should be the default (end of disk)
      6. w (for writing to disk)
  7. Now check the partition and resize it
    1. Run this command making sure to use the right device path (but add a 1 to the end for the first partition)
      1. e2fsck -f /dev/xvdf1
    2. Resize the partition making sure to use the right device path (but add a 1 to the end for the first partition)
      1. resize2fs /dev/xvdf1
  8. Shutdown the instance “fix-the-disk-instance”
    1. Go to EC2 > Instances
    2. Select the Instance “fix-the-disk-instance”
    3. Click “Actions” > “Instance State” > Stop
  9. Detach the block device and reattach it to the original server
    1. Go to EC2 > Volumes
    2. Find the volume by looking under Attachment Information for the instance name (e.g. fix-the-device-instance).
    3. Make sure it is the right volume by looking at the ID/Size.
    4. Select the volume
    5. Click “Actions” > “Detach Volume”
    6. Click “Actions” > “Attach Volume”
    7. IMPORTANT: enter “/dev/sda1” as the device so it attaches as the root volume
    8. Attach it to the original server
  10. Start “fix-the-disk-instance” and login
    1. Go to EC2 > Volumes
    2. Select the original instance (e.g. “snap.appcove.net”)
    3. Click “Actions” > “Instance State” > Start
    4. Wait for it to start

 

And that’s all!

 

 

2016-03-20 - B162957

2016-03-20 - B164242

2016-03-20 - B164338

 

 

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Example Automated MySQL Backup Script

Rather than use --all-databases, which will prevent you from being able to selectively restore any single database, consider the following:

Ideally, you should have a daily backup, with some history. It should be bulletproof (--force), it should be logged (>> ...log), it should be compressed (| gzip), it should keep separate copies of each database, and it should automatically pick up any databases that are added.

Consider, rather, a shell script like this:

#!/bin/bash

Host=server.domain.com
BDir=/home/backup/backup/mysql

Dump="/usr/bin/mysqldump --skip-extended-insert --force"
MySQL=/usr/bin/mysql

Today=$(date "+%a")

# Get a list of all databases
Databases=$(echo "SHOW DATABASES" | $MySQL -h $Host)

for db in $Databases; do
        date=`date`
        file="$BDir/$Host-$db-$Today.sql.gz"
        echo "Backing up '$db' from '$Host' on '$date' to: "
        echo "   $file"
        $Dump -h $Host $db | gzip > $file
done



Which is assuming that you have a file ~/.my.cnf (chmod 600), that has:


[client]
user = "BACKUP"
password = "SOMEPASS8342783492"



Make sure that whatever user you are using for BACKUP has this grant statement:


GRANT
  SELECT, SHOW VIEW ON *.*
  TO BACKUP@localhost
  IDENTIFIED BY 'SOMEPASS8342783492';



So simply add this to a nightly cronjob, and you have a daily backup that rotates each 7 days week.


0 3 * * *   backup-mysql >> backup-mysql.log 2>> backup-mysql.log





The backup directory then contains:


-rw-r--r-- 1 backup backup 2217482184 Sep  3 13:35 base.appcove.net-VOS4_0-20090903.sql.gz
-rw-rw-r-- 1 backup backup 2505876287 Dec 25 00:48 base.appcove.net-VOS4_0-Fri.sql.gz
-rw-r--r-- 1 backup backup 2500384029 Dec 21 00:48 base.appcove.net-VOS4_0-Mon.sql.gz
-rw-r--r-- 1 backup backup 2506849331 Dec 26 00:48 base.appcove.net-VOS4_0-Sat.sql.gz
-rw-r--r-- 1 backup backup 2499859469 Dec 20 00:48 base.appcove.net-VOS4_0-Sun.sql.gz
-rw-rw-r-- 1 backup backup 2505046147 Dec 24 00:48 base.appcove.net-VOS4_0-Thu.sql.gz
-rw-rw-r-- 1 backup backup 2502277743 Dec 22 00:48 base.appcove.net-VOS4_0-Tue.sql.gz
-rw-r--r-- 1 backup backup 2504169910 Dec 23 00:48 base.appcove.net-VOS4_0-Wed.sql.gz
-rw-r--r-- 1 backup backup   76983829 Dec 25 00:49 base.appcove.net-VOS4_Mail_0-Fri.sql.gz
-rw-r--r-- 1 backup backup   76983829 Dec 21 00:49 base.appcove.net-VOS4_Mail_0-Mon.sql.gz
-rw-r--r-- 1 backup backup   76983829 Dec 26 00:49 base.appcove.net-VOS4_Mail_0-Sat.sql.gz
-rw-r--r-- 1 backup backup   76983829 Dec 20 00:48 base.appcove.net-VOS4_Mail_0-Sun.sql.gz
-rw-rw-r-- 1 backup backup   76983829 Dec 24 00:49 base.appcove.net-VOS4_Mail_0-Thu.sql.gz
-rw-rw-r-- 1 backup backup   76983829 Dec 22 00:49 base.appcove.net-VOS4_Mail_0-Tue.sql.gz
-rw-r--r-- 1 backup backup   76983829 Dec 23 00:49 base.appcove.net-VOS4_Mail_0-Wed.sql.gz
-rw-r--r-- 1 backup backup  304803726 Dec 25 00:49 base.appcove.net-WeSell_0-Fri.sql.gz
-rw-r--r-- 1 backup backup  303480087 Dec 21 00:49 base.appcove.net-WeSell_0-Mon.sql.gz
-rw-r--r-- 1 backup backup  304710121 Dec 26 00:49 base.appcove.net-WeSell_0-Sat.sql.gz
-rw-r--r-- 1 backup backup  303791294 Dec 20 00:49 base.appcove.net-WeSell_0-Sun.sql.gz
-rw-rw-r-- 1 backup backup  305315415 Dec 24 00:49 base.appcove.net-WeSell_0-Thu.sql.gz
-rw-rw-r-- 1 backup backup  302516217 Dec 22 00:49 base.appcove.net-WeSell_0-Tue.sql.gz
-rw-r--r-- 1 backup backup  303314217 Dec 23 00:49 base.appcove.net-WeSell_0-Wed.sql.gz
-rw-r--r-- 1 backup backup     135301 Dec 25 00:30 dc40.appcove.net-mysql-Fri.sql.gz
-rw-r--r-- 1 backup backup     135301 Dec 21 00:30 dc40.appcove.net-mysql-Mon.sql.gz
-rw-r--r-- 1 backup backup     135301 Dec 26 00:30 dc40.appcove.net-mysql-Sat.sql.gz
-rw-r--r-- 1 backup backup     135301 Dec 20 00:30 dc40.appcove.net-mysql-Sun.sql.gz
-rw-rw-r-- 1 backup backup     135301 Dec 24 00:30 dc40.appcove.net-mysql-Thu.sql.gz
-rw-rw-r-- 1 backup backup     135301 Dec 22 00:30 dc40.appcove.net-mysql-Tue.sql.gz
-rw-r--r-- 1 backup backup     135301 Dec 23 00:30 dc40.appcove.net-mysql-Wed.sql.gz
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Updating a cert on the Cisco 11500 Series Content Services Switches (CSS)

Having recently moved some of our hosting infrastructure to the excellent Rackspace Platform group, we inherited the management of the Cisco 11500 Series Content Services Switches (CSS), which we use for general load balancing + ssl termination.

As a side note, it’s really powerful, fast, and well, plain nice.  Not having to manage SSL certs on each apache instance is really nice, and all the LAN communication is done over plain old HTTP.

This blog post is a regurgitation of some notes I took internally.  Perhaps someone who finds themselves managing this device will benefit…

The task at hand was re-issuing and updating one of our primary wildcard certificates that powers a lot of subdomains.

The first step is to generate the key, csr, and crt…

All these files should be:

  • Named the same as the domain that SSL is being generated for.
  • use WILD for a wildcard subdomain
  • Use this format “www.domain.com-0810.key”, where 08 is the from year and 10 is the to year
  • (the short version is because of name length limits on the CSS)

Start by generating the key and csr

This should be done in the ciscoftp role under the ~/load directory

# openssl genrsa -out WILD.vosecure.com-0810.key 1024
# openssl req -new -key WILD.vosecure.com-0810.key -out WILD.vosecure.com-0810.csr

Then get the certificate issued by (global sign)

Put the certificate into the the ~/load directory.  When done, it should look like:

-rw-rw-r-- 1 ciscoftp ciscoftp  3139 Apr  6 15:59 WILD.vosecure.com-0810.crt
-rw-rw-r-- 1 ciscoftp ciscoftp   773 Apr  6 15:49 WILD.vosecure.com-0810.csr
-rw-rw-r-- 1 ciscoftp ciscoftp   883 Apr  6 15:47 WILD.vosecure.com-0810.key

Put the crt and key onto the load balancer

To do this, use the “copy command” on the load balancer

20132-201292# copy ssl ftp base import WILD.vosecure.com-0810.crt PEM "rack"
20132-201292# copy ssl ftp base import WILD.vosecure.com-0810.key PEM "rack"

Then make the associations...

20132-201292# config
20132-201292(config)# ssl associate cert WILD.vosecure.com-0810.crt WILD.vosecure.com-0810.crt 
20132-201292(config)# ssl associate cert WILD.vosecure.com-0810.key WILD.vosecure.com-0810.key

Now, it’s time to install it.  Requires SSL downtime!

  1. Suspend the SSL content rule
  2. Suspend the SSL service
  3. Suspend the SSL proxy list
  4. Run the updates
  5. Activate the SSL proxy list
  6. Activate the SSL service
  7. Activate the SSL content rule

Here are the exact commands:

20132-201292# config
20132-201292(config)# owner vosecure.com
20132-201292(config-owner[vosecure.com])# content 74.205.111.161-ssl
20132-201292(config-owner-content[vosecure.com-74.205.111.161-ssl])# suspend

20132-201292# config
20132-201292(config)# service ssl-service
20132-201292(config-service[ssl-service])# suspend

20132-201292# config
20132-201292(config)# ssl-proxy-list ssl-proxy

In the following commands, we remove the whole ssl-server so that it shows up at the bottom in one concise unit. Otherwise, the startup-config and running-config become fragmented.

20132-201292(config-ssl-proxy-list[ssl-proxy])# suspend
20132-201292(config-ssl-proxy-list[ssl-proxy])# no ssl-server 6
20132-201292(config-ssl-proxy-list[ssl-proxy])# ssl-server 6
20132-201292(config-ssl-proxy-list[ssl-proxy])# ssl-server 6 rsakey WILD.vosecure.com-0810.key
20132-201292(config-ssl-proxy-list[ssl-proxy])# ssl-server 6 rsacert WILD.vosecure.com-0810.crt
20132-201292(config-ssl-proxy-list[ssl-proxy])# ssl-server 6 vip address 192.168.1.161
20132-201292(config-ssl-proxy-list[ssl-proxy])# ssl-server 6 cipher rsa-with-rc4-128-sha 192.168.1.161 81
20132-201292(config-ssl-proxy-list[ssl-proxy])# active

20132-201292# config
20132-201292(config)# service ssl-service
20132-201292(config-service[ssl-service])# active

20132-201292# config
20132-201292(config)# owner vosecure.com
20132-201292(config-owner[vosecure.com])# content 74.205.111.161-ssl
20132-201292(config-owner-content[vosecure.com-74.205.111.161-ssl])# active

Test test test.  Firefox, IE, Chrome...

20132-201292# copy running-config ftp base running-config

Review changes with git diff

20132-201292# write memory

20132-201292# copy startup-config ftp base startup-config

And… Here is the git diff

diff --git a/load/startup-config b/load/startup-config
index 7042490..36fbbaa 100644
--- a/load/startup-config
+++ b/load/startup-config
@@ -1,4 +1,4 @@
-!Generated on 04/06/2009 16:05:48
+!Generated on 04/06/2009 21:51:02
!Active version: sg0810205

@@ -64,6 +64,8 @@ configure
+  ssl associate rsakey WILD.vosecure.com-0810.key WILD.vosecure.com-0810.key
+  ssl associate cert WILD.vosecure.com-0810.crt WILD.vosecure.com-0810.crt

!*********************** SSL PROXY LIST ***********************
ssl-proxy-list ssl-proxy
-  ssl-server 6
-  ssl-server 6 rsakey vosecure.com(080421-04300)-key
-  ssl-server 6 rsacert vosecure.com(080421-04300)-cert
-  ssl-server 6 vip address 192.168.1.161
-  ssl-server 6 cipher rsa-with-rc4-128-sha 192.168.1.161 81
@@ -146,6 +141,11 @@ ssl-proxy-list ssl-proxy
+  ssl-server 6
+  ssl-server 6 rsakey WILD.vosecure.com-0810.key
+  ssl-server 6 rsacert WILD.vosecure.com-0810.crt
+  ssl-server 6 vip address 192.168.1.161
+  ssl-server 6 cipher rsa-with-rc4-128-sha 192.168.1.161 81
active
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I highly recommend yum + createrepo + rpmbuild

As I was discussing lightly before, I have recently been involved in building quite a few RPMs for our server clusters at AppCove.

Where we have arrived:

Our (new) primary production cluster consists of multiple RedHat Enterprise Linux 5 boxes in different capacities (webserver, appserver, database master, database slave, etc…).

Each machine is registered with 3 yum repositories:

  1. RHEL (RedHat Enterprise Linux)
  2. EPEL (Extra Packages for Enterprise Linux)
  3. ACN (AppCove Network)

All of our custom software packages and custom builds of open source software are placed into individual RPMs, and entered into our ACN repository.

From there, it is a snap to update any given server with the correct version of the software that server needs.

We have a dedicated build area, versioned with git, that is used to build and package all of the custom software that is needed.

(note, RPMs are not used for web application deployment — rsync via ssh is used for that)

Recommendation:

Having worked through the process from start to finish, I must say that I would highly recommend the following tools to anyone who is responsible for RedHat Enterprise, Centos, or Fedora system administration.

  • git – to keep your .spec files versioned
  • rpmbuild – to build the rpms
  • createrepo – to create your very own yum repository
  • apache – to serve the yum repository
  • yum – to obtain, install, and upgrade your rpms

Additionally, if you are using RedHat Enterprise or Centos, I would highly recommend using Extra Packages for Enterprise Linux (EPEL) to get a few of those “other” packages that don’t come with your OS (git, for example).

—
Learning how to build RPMs was a fairly steep curve.  But it wasn’t long.  It is one of those things that if you know it you say “that’s easy” and if you don’t you say “what the ???”

yum+rpm was invented (I assume) to make life easier for countless system administrators and software publishers.  So it’s not the kind of thing that everyone is involved in.

I was a bit tough to figure out the caveats of how to correctly build RPM’s that work.  The documentation is a bit sparse.  A bit here and a bit there.

What are the benefits?

Many.  Let me list a few.

Your system stays really clean. With RPMs, you can uninstall everything you installed without leaving extra files laying around.

Upgrades are a snap. Once you have registered your own yum repository on a system, you can upgrade a given package by running:

yum upgrade your-package

All your systems can be on the same “page”. It is very easy, using yum, to ensure that all of your systems are using the exact same version of software.

Custom builds are super easy to maintain. We custom-compile php, python, and various other software.  Once the .spec files are in place, all of your software can be re-packaged with a single command.

In our specific case, we wanted to have the memcached client statically compiled into PHP.  With a few extra commands in the .spec file, it was a snap to pull in the source from pecl, and update `configure` to take it into account.

All builds can take place in one place. With one set of documentation, one consistent set of development tools, etc…  We have a user called `build` on one of the hosts that is specifically used for building all of the RPMs.

Where to learn?

The best way to learn, as usual, is to jump in and figure it out.   There is some really good documentation buried in the rpm.org site.   It is a book called Maximum RPM, origninally published by redhat.  The current snapshot of the book is available online.

http://www.rpm.org/max-rpm-snapshot/

Google is another good resource, depending on what it is you are looking for.