A new public EC2 AMI with Smalltalk and Seaside
This weekend I created a public Amazon Machine Image (AMI) setup as a Smalltalk web server with a Linux SqueakVM, a Pharo 1.1 Smalltalk image and the Apache2 web server. Anyone can use this AMI as a robust and scalable runtime platform for their Seaside applications.
In this article I will try to explain how you can you can use and customize this image. First their are some prerequisites:
- You need an Amazon AWS account and you should sign up for the Elastic Compute Cloud (EC2) service.
Using EC2 is not free, you have to pay for each hour the server runs and you have to pay for storage and bandwidth. Seaside runs fine on the smallest 32bit AMI that costs $0,085 cents per hour. Bandwidth is $0,15 per GB (the first GB is free). You can get a discount on the costs per hour if you reserve you AMI’s beforehand.
The AMI is based on a 32bit Ubuntu 10.04 server AMI. The Ubuntu server is a very minimal install, I have added Apache2 and the SqueakVM. I have also setup a Pharo image with the Seaside runtime packages and Apache2 is configured in such a way that all requests are forwarded to Seaside.
How can you start using this AMI?
Start an EC2 instance using the public AMI ami-0800ea61 (ubuntu-10.04-i386-smalltalk-server-v01). The AMI is available in the US East region. This is the cheapest region :-) When you start the image you have to select a security group. This defines the firewall rules for the AMI. You can select the default group or some other group that allows TCP connections for the ports 22 and 80.
When the image is started it should have a generated a public DNS name. When you enter this name in the address bar of your browser, you should see something similar to http://ec2demo.doit.st If the web page is shown it means that everything is running OK.
You can connect to the running AMI instance using ssh. You should login with the userid ubuntu. No password is required because a private key is used for authentication. The Pharo image that runs on the AMI includes RFB, a VNC server implementation. With a VNC client we can remotely control the Smalltalk image. The best way to do this is to tunnel the VNC connection (port 5900) through ssh:
ssh -i id_rsa-gsg-keypair -L 5900:localhost:5900 email@example.com
Now you can connect to the image using a VNC client use display number 0 and the password is seaside. Note that you have to keep port 5900 closed for direct access otherwise this would be very unsecure.
Through the VNC client you have access to the Smalltalk image. You should see a workspace. I used the code in this workspace to build the image from a standard PharoCore 1.1 image. Note that I only loaded the runtime parts of Seaside and some small examples. This image is used for hosting an application and not for development so it is probably safer and more efficient to leave out the development packages.
If the image suits your needs you can just load your packages through Monticello. There is no config web application to configure your Seaside components. You can do this via the workspace or better, make a class side initialize method that does this automatically when the package is loaded. I used the the Apache2 configuration described in the Seaside book (the non-clustered setup for now). You can read the Deployment chapter for more details. You should have you app running within a few minutes.
If the Smalltalk image does not suit your needs you can replace it with another Squeak or Pharo image. The image is stored in the directory /srv/seaside If your new image has a different name you need to update the run script in the same directory.
Of course you can also install more Ubuntu packages. You could install a local database system like MySQL or PostgreSQL. But if you are really into cloud computing you probably don’t want to maintain a database yourself. Instead you can use RDS, an AWS managed MySQL service or SimpleDB. SimpleDB is a key-value store with a simple API and great scalability. You can use the Cloudfork ActiveItem Smalltalk library to persist your Smalltalk objects to SimpleDB.
To setup a nice domain name for your app (like ec2demo.doit.st) you should reserve a static IP using the AWS Console. You can then go to your domain name registrar and update the name servers to point to this IP number.
Ok, this is about it. If you have questions or ideas on how to improve the Smalltalk AMI please let me now. I think the current AMI can be used as a production environment for Seaside apps.Cloudfork