Monday, December 31, 2012

Creating and Uploading Eucalyptus Images

By far the best reference I've found on the subject:

Simple, elegant and most importantly no BS! I've tried these steps out several times in Euca2 and Euca3 and they work like a charm. Nice work Igor.

Saturday, December 29, 2012

Deploying Applications in the Cloud Using AppScale

In my last two posts I briefly explained how to setup AppScale and get it up and running. Once you have a running AppScale PaaS, you can start deploying webapps in the cloud. You develop webapps for AppScale using Google App Engine (GAE) SDK. AppScale is fully API compatible with GAE and therefore any GAE application can be deployed on AppScale with no code changes. If you do not have any GAE applications to try on AppScale, you may follow one of the official GAE tutorials and develop a sample GAE application using Python, Java or Go. Alternatively you can checkout the AppScale sample-apps repository and try to deploy one of the pre-packaged sample apps. To checkout the sample-apps repository, execute the following command on a shell:
git clone
This will checkout a directory named sample-apps to your local disk. This directory contains 3 subdirectories named python, java and go. As the names suggest, each subdirectory contains a number of sample GAE applications written in the corresponding language. One of the simplest sample applications available for you to try out is the "guestbook" application. The Python version of the application can be found in the sample-apps/python/guestbook directory and the Java version of it can be found in the sample-apps/java/guestbook directory. This application provides a simple web front-end for users to enter a comment and browse comments entered by other users. It uses the GAE datastore API under the hood to store and retrieve comments entered by users. You can use AppScale-Tools to upload the guestbook application to your AppScale cloud.
appscale-upload-app --file samples-apps/python/guestbook --keyname appscale_test
The keyname flag should indicate the keyname you provided when starting the AppScale instance using the appscale-run-instances command. Once you execute the above command you will be prompted to enter the admin e-mail address for your application. Here you can enter the admin e-mail address you used when starting AppScale. Application deployment could take a few minutes. If everything goes smoothly, tools will print the URL through which your webapp can be accessed.
Your app can be reached at the following URL:
Try uploading a few applications using the above command and see how it goes. You can also try developing your own custom apps and deploying them in the cloud. 
AppScale-Tools also allow you to start an AppScale cloud with an application preloaded. To invoke this feature, you simple need to pass the --file option to the appscale-run-instances command.
appscale-run-instances --min 10 --max 10 --infrastructure euca --machine emi-12345678 --keyname appscale_test --group appscale_test --file samples-apps/python/guestbook
To undeploy an application you can use the appscale-remove-app command.
appscale-remove-app --appname guestbook --keyname appscale_test
Finally you can terminate and tear down an AppScale PaaS using the appscale-terminate-instances command.
appscale-terminate-instances --keyname appscale_test
If your AppScale PaaS was running in over an IaaS layer such as EC2, the above command will also take care of terminating the VMs in the cloud.
In my next few posts, I'll explain a little bit about GAE APIs and how to implement cool apps for AppScale using those APIs.

Wednesday, December 26, 2012

Starting AppScale

This post is written assuming you already have a machine or a VM image with AppScale and AppScale-Tools installed. If you don't please refer to my previous post on "Setting Up AppScale". 
We use AppScale-Tools to start, manage and terminate AppScale instances in various environments. The inputs we should pass into the tools differ slightly based on the environment in which we want to start AppScale. If you're going to deploy AppScale without the help of an IaaS layer like EC2 or Eucalyptus, then you're responsible for manually starting up the required machines or VMs. For an example if you're going to run AppScale on the Xen hypervisor, then you should first start your AppScale Xen images manually. Similarly if you're going to run AppScale over VMWare Fusion, you should start your AppScale Fusion images manually. Once the instances are up and running note down their IP addresses (assuming that the instances obtain IP addresses from a service such as DHCP). As an example lets assume you have 3 VM instances up and running and their IP addresses are, and With this information we should compile a simple YAML configuration like this:
Lets call this file ips.yaml. This configuration instructs AppScale to use one machine as the controller and the rest as ordinary nodes. The controller (aka head node) operates as a load balancer and a ZooKeeper leader. The other nodes will assume the roles of application server and DB server. In this case both server nodes will assume the application server and DB server roles. Therefore we end up with an application server cluster (of 2) and a replicated DB cluster (of 2) fronted by a single load balancer. You can further fine tune how AppScale assigns roles to machines by changing your ips.yaml file. For more information regarding the role placement configuration please refer the "Placement Support" article on AppScale wiki.
Once you have your ips.yaml file you can start deploying AppScale on the VMs. First create a SSH key-pair so that AppScale-Tools can login to the relevant machines remotely. This is done by executing the appscale-add-keypair command.
appscale-add-keypair --ips /path/to/ips.yaml
This will prompt you to enter the root passwords for each of the machines specified in your ips.yaml. Once this step has completed you can fire off AppScale using the app scale-run-instances command.
appscale-run-instances --ips /path/to/ips.yaml
This will start the AppScale daemons on each of the machines and initialize the AppScale PaaS. At some point you will be prompted to enter an email address and a password for the AppScale admin account. Just enter any email address or password for this. You can later use these credentials to login to AppScale management console. (For more details on deploying AppScale over a virtualized cluster setup refer the AppScale wiki)
If you are deploying AppScale over an IaaS layer such as EC2 or Eucalyptus, then you don't need to start the VMs manually nor you need any ips.yaml file. All you need is the unique ID of your AMI or EMI provided by your IaaS provider and the security credentials to interact with the IaaS. In case of EC2 you will need your AWS access key, secret key, AWS private key and X509 certificate. You can get these from the security credentials page of your AWS management console. If you're on Eucalyptus you can download a zip file from Euca admin console which contains all the required credentials.
Using these credentials you should first setup some environment variables.
export EC2_CERT=~/mycert.pem 
export EC2_PRIVATE_KEY=~/mypk.pem 
export EC2_ACCESS_KEY=my-access-key 
export EC2_SECRET_KEY=my-secret-key
In case of Eucalyptus you can simply source the eucarc file found in the downloaded credentials file.
source eucarc
With these environment variables in place you're ready to go. Simply execute the app scale-run-instances command as follows.
appscale-run-instances --min 1 --max 1 --infrastructure ec2 --machine ami-52912a3b --keyname app scale_test --group app scale_test
This will start a simple 1-node AppScale cloud in EC2. If you want more instances in your PaaS, simply adjust the values of min and max flags. For deployment on Eucalyptus change the value of infrastructure flag to 'euca' and provide a valid EMI ID for the machine flag. Here's the command for a 10 node AppScale deployment over Eucalyptus.
appscale-run-instances --min 10 --max 10 --infrastructure euca --machine emi-12345678 --keyname app scale_test --group app scale_test
The values of keyname and group flags will be used to create a keypair and a security group in the respective IaaS environment. Therefore make sure they are unique for your EC2/Eucalyptus account. Note that when running in a billed environment such as EC2, the machines spawned by AppScale are billed against the EC2 credentials provided (the credentials that we set as environment variables). AppScale spawns m1.large instances which cost about 26 cents an hour.
An AppScale deployment could take several minutes to complete. In environments like EC2 and Eucaplyptus, deployment times over 10 minutes are not uncommon. This delay is primarily due to the VM bootup and initialization overhead of IaaS environments which cannot be avoided. Once the AppScale deployment is complete AppScale-Tools will spit out a URL that you can use to check the status of the AppScale deployment:
The status of your AppScale instance is at the following URL:
Simply copy and paste the URL into your web browser to view the AppScale status page.
In my next post I'll explain how to deploy applications in an already running AppScale PaaS.

Tuesday, December 25, 2012

Setting Up AppScale

The AppScale installation procedure is already well documented in the AppScale wiki. Therefore this blog post only serves as a summary and a refresher of the most important steps. The installation of AppScale usually boils down to creating a virtual machine (VM) image for the environment in which you intend to deploy AppScale. For an example, if you wish to deploy AppScale on Amazon EC2, then you need to create an EC2 AMI with AppScale installed on it. If you wish to run AppScale on Eucalyptus, you will be creating a Eucalyptus EMI with AppScale on it. Similarly you can create AppScale VM images for other virtualized environments (eg: Xen, Virtual Box, Fusion etc). The only exception to this is when you want to deploy AppScale without a virtualization layer. In that case you can directly install AppScale on the host operating system.
As of the time of writing, AppScale is only supported on Ubuntu Lucid 10.04 Server Edition. This is common to all the target environments. Therefore regardless of the virtualization layer you intend to use, your AppScale VM image must be running Ubuntu Lucid 10.04 Server Edition. However we will start supporting newer versions of Ubuntu pretty soon therefore I'd recommend you to refer the AppScale wiki to find out about the latest OS supported by the system. 
Once you have procured your Ubuntu Lucid image you can boot it up and start installing AppScale on it. First login to the VM as root. We will use the command-line Git client to pull the latest AppScale source code on to the VM. But first we need to install the command-line Git client.
apt-get install git-core
Now clone the AppScale and AppScale-Tools repositories to the home directory of root.
git clone
git clone
If you want to pull any recent bug fixes or improvements, simply pull the AppScale testing branches. You can do this by adding "--branch testing" flag to the above two commands. Once you have the two repositories checked out, simply change into the appscale directory and run the following command to kick off the build process.
bash debian/
AppScale build can take about 20-30 minutes depending on how fast your Internet connection is. Once the AppScale build is complete check for a directory named /etc/appscale. This should contain a subdirectory named after the version of AppScale you just installed and this subdirectory should contain a collection of text files named after different database engines (eg: cassandra, hbase etc). If these files are in place that's a pretty reasonable indication that everything has gone according to the plan. Now change into appscale-tools directory you checked out earlier, and run the same build command as above to start building the AppScale command-line tools. This shouldn't take more than a few seconds. 
You are now done installing AppScale on the VM image. You can now go ahead and start bundling/packing the VM image for your target environment. For an example if you're going to run AppScale on EC2, you can start the AMI bundling process now. The actual procedure for bundling and uploading VM images will depend on your target environment.
It is particularly trivial to setup AppScale in the EC2 environment. The EBS technology of Amazon makes it absolutely simple to create AMI images with AppScale. Here's all you have to do:
1. Start a fresh Ubuntu Lucid 10.04 EBS image (eg: ami-1634de7f). If you start this VM as a m1.large instance the whole thing will be over much quicker.
2. Run the above described procedure to checkout and build AppScale on the EC2 instance.
3. Login to your AWS management console. Right click on your EC2 instance and select the "Create Image (EBS AMI)" option from the menu that appears. This will start bundling your AppScale AMI and it will be available for deployment within several minutes.
It is sometimes necessary to create VM images with only the AppScale-Tools. In this case you may only checkout the AppScale-Tools source code and build it. However you will have to install a few additional libraries manually.
apt-get install openjdk-6-jre
apt-get install ruby
apt-get install rubygems
apt-get install ruby1.8-dev
gem install json
This should enable you to run AppScale-Tools on your VM image.
In my next post I'll describe how to start AppScale and deploy applications on the AppScale PaaS.