Amazon EC2

Amazon's Cloud provides a flexible platform to deploy Eden scalably.

The costs aren't fixed & can be difficult to predict, despite their ​calculator, but are competitive, especially in Singapore, which is a good base for the Asia Pacific region.

Regions & Zones

Amazon supports multiple Regions in order to provide a service closest to your users.

• Namespaces of Instances, Volumnes & Snapshots are unique only within a Region.
• Within each Region, there are a couple of Availability Zones to allow spreading the risk across different facilities.
• Volumes are located within a specific Availability Zone
• Bandwidth transfers are free within an Availability Zone

Instance Size

• The free starter 'micro' instance is flexible as it can run both 32-bit & 64-bit Operating Systems.
• The normal production 'small' instance can only run 32-bit.
• Larger production instances can only run 64-bit, so can't have the exact same image used.

Instance Persistence

• EBS-backed instances have persistent storage even whilst powered down, which is very useful.
  • For DB I/O performance increase can stripe multiple EBS
    • monitoring data available to see if this is the issue

AMI

• Recomemnd using the AWS Marketplace Debian image (as this has a sufficiently large HDD to start with). Alternately use the community EBS Debian Squeeze-base i386 AMI.
  • These can be turned into an Eden instance via the scripts found in Cherokee & PostgreSQL - see #Install
• In time we may provide pre-built "Sahana Eden" AMIs
  • some old unmaintained ones may be available in some regions (e.g. us-west). These just need to be configured via ./configure-eden-cherokee-postgis.sh

Elastic IP

Each time you start an instance up, it will be assigned a new IP ('Public DNS') although this can be overcome using an Elastic IP

• Remember to set up Reverse DNS for your Elastic IP to be able to send emails reliably:
  • ​https://aws-portal.amazon.com/gp/aws/html-forms-controller/contactus/ec2-email-limit-rdns-request

Authentication

SSH

This can provide an early stumbling block.

• Each instance created needs to start with a unique SSH keypair
• When setting up an instance, be sure to safely download the private key.
• In order to get the public key (needed by SecureCRT for instance) then you need to login using CLI & retrieve it (username 'admin' for the AWS MarketPlace Debian, username 'root' for some other Images):

  ssh -l admin -i private.pem <hostname>
  cat ~/.ssh/authorized_keys
  
  

SecureCRT needs the private key storing as <filename> & the public as <filename.pub> (all on one line)

SSH will also need to be enabled in your Firewall policy (restrict the IP source, if possible)

Retrieving Lost Keypair

If you lose your keypair then you need to:

• Create a new keypair in the AWS console & download the generated private key
• Stop the instance
• Create an AMI from this instance
• Wait for the AMI to be ready
• Launch a new instance using this AMI
• Re-associate the Public IP
• Delete the old instance
• Deregister the AMI
• Delete the snapshot used to create the AMI

Thanks to: ​http://itkbcentral.blogspot.co.uk/2011/07/replace-lost-key-pair-existing-aws-ec2.html

Add Swapfile

• You can add swap from a swap file in order to improve performance (especially on a Micro instance):

  dd if=/dev/zero of=/swapfile1 bs=1024 count=524288
  mkswap /swapfile1
  chown root:root /swapfile1
  chmod 0600 /swapfile1
  swapon /swapfile1
  # Make persistent across reboots
  cat << EOF >> "/etc/fstab"
  /swapfile1 swap swap defaults 0 0
  EOF
  
  

Install

• Copy the installation and configuration scripts -> install-eden-cherokee-postgis.sh and configure-eden-cherokee-postgis.sh into the launched instance.

  wget http://eden.sahanafoundation.org/raw-attachment/wiki/InstallationGuidelines/Linux/Server/CherokeePostgreSQL/install-eden-cherokee-postgis.sh
  chmod a+x install-eden-cherokee-postgis.sh
  wget http://eden.sahanafoundation.org/raw-attachment/wiki/InstallationGuidelines/Linux/Server/CherokeePostgreSQL/configure-eden-cherokee-postgis.sh
  chmod a+x configure-eden-cherokee-postgis.sh
  
  

• Run the install-eden-cherokee-postgis.sh script. [Note: This step takes about 10min - grab a coffee]

  ./install-eden-cherokee-postgis.sh
  
  

Configure

Run configure-eden-cherokee-postgis.sh to configure the instance:

./configure-eden-cherokee-postgis.sh

• Add a Test site (4Gb+)

  wget http://eden.sahanafoundation.org/raw-attachment/wiki/InstallationGuidelines/Linux/Server/CherokeePostgreSQL/add_test_site.sh
  chmod a+x add_test_site.sh
  ./add_test_site.sh
  rm add_test_site.sh
  

Grow the Diskspace

The disk space on the initial image is just 1GB. This should be grown to 4Gb (don't just size the volume to 4Gb to start with as the image only uses 1Gb of it!)

• this is still within the 10Gb free tier.
• 4Gb is needed for Prod & Test instances. If you just need a test then 3Gb is sufficient.

You can do this using the AWS EC2 Console or else you can do it via the CLI

CLI Tools

To use any of the AWS CLI tools on your own machine to remotely manage instances, then you need to generate a unique X.509 Certificate per account. This can be done from the 'Security Credentials' page within your account.

CLI Management

There are extensive CLI tools available to manipulate your instances.

• Java CLI for Windows/Linux
  • ​http://aws.amazon.com/developertools/351
  • ​http://serktools.com/2009/05/19/setting-up-ec2-command-line-tools-on-windows/
  • ​http://docs.amazonwebservices.com/AWSEC2/latest/CommandLineReference/
• Python: ​http://libcloud.apache.org

CLI Script

Edit the settings as-indicated as you proceed through the script

# Settings for Instance
set EC2_URL=https://ec2.us-east-1.amazonaws.com
set ZONE=us-east-1c
set DEV=i-950895f1
set OLD=vol-31f5a35d
# Stop Host
ec2stop %DEV%
# Create a snapshot
ec2-create-snapshot %OLD%
# Record the snapshot ID
set SNAPSHOT=snap-63f89d08
# Create new volume from snapshot
ec2-create-volume -z %ZONE% --size 4 --snapshot %SNAPSHOT%
# Record the new Volume ID
set NEW=vol-a9c2a3c4
# Attach new volume as secondary
ec2-attach-volume -i %DEV% %NEW% -d /dev/sdb1
# Delete Snapshot (if no data in yet)
ec2-delete-snapshot %SNAPSHOT%
# Start Host
ec2start %DEV%
# Re-attach the Public IP
# Login
mkdir /mnt/data
echo '/dev/xvdb1 /mnt/data ext3 defaults,noatime 0 0' >> /etc/fstab
mount /mnt/data
resize2fs /dev/xvdb1
umount /mnt/data
shutdown -h now
# Unattach volumes
ec2-detach-volume -i %DEV% %OLD%
ec2-detach-volume -i %DEV% %NEW%
# Attach volume as boot
ec2-attach-volume -i %DEV% %NEW% -d /dev/sda1
# Attach old volume for /var/log
ec2-attach-volume -i %DEV% %OLD% -d /dev/sdb1
# OR Delete old volume
#ec2-delete-volume %OLD%
# Start Host
ec2start %DEV%
# Re-attach the Public IP
# Login
df -h
# Use the old partition for /var/log (to avoid DoS)
vi /etc/fstab
/dev/xvdb1 /var/log  ext3    noatime 0 0

mv /var/log /var/log_old
mkdir /var/log
mount /var/log
mv /var/log_old/* /var/log
rm -rf /var/log/bin/
rm -rf /var/log/boot/
rm -rf /var/log/dev/
rm -rf /var/log/etc/
rm -rf /var/log/home/
rm -rf /var/log/initrd.img
rm -rf /var/log/lib/
rm -rf /var/log/mnt/
rm -rf /var/log/media/
rm -rf /var/log/opt/
rm -rf /var/log/proc/
rm -rf /var/log/root/
rm -rf /var/log/sbin/
rm -rf /var/log/selinux/
rm -rf /var/log/srv/
rm -rf /var/log/tmp/
rm -rf /var/log/usr/
rm -rf /var/log/var/
rm -rf /var/log/vmlinuz
rm -rf /var/log_old

Building AMIs for easier deployment

If your region doesn't yet have a Sahana AMI in, then it is easy to create one which allows easier deployment of future instances for both you & others. The only cost to you is a small amount of time to publish it & then using up your 1Gb Snapshot allowance within the free tier.

• Install the instance as-above
• Don't run the configure script
• Shutdown the EBS instance.

  shutdown -h now
  
  

• Go to your aws console for the current region at ​| EC2 Console

• Select the debian instance you just prepared in the "Instances"

• Select " Create Image (EBS AMI) " in the "Instance Actions" drop down.

• Choose an Image name - Lets say - "Sahana Eden" and fill in a description.

• Click "Create this Image"

• Go to the "AMIS" menu and select "Owned by me" and "All Platforms" in the Viewing dropdown.

• Wait for about 5 minutes and hit refresh for the AMI you just built to appear.

• Select the AMI and click the Permissions button - Select public, to make the image public.

Keep Templates as EBS Volumes as this is cheaper than Snapshots

Next

Administration Guide