scripts.mit.edu

MIT SIPB Script Services for Athena

scripts.mit.edu Fedora 11 Transition

Overview

On Thursday, July 9, 2009, all of the scripts.mit.edu servers were upgraded from Fedora 9 to Fedora 11, which was released on June 9. We strongly encourage you to test your website as soon as possible, and to contact us at scripts@mit.edu if you experience any problems. The easiest way to test your site is to run the following commands at an Athena workstation and then visit your website in the browser that opens, but see below for more details:

athena% add scripts
athena% firefox-test

Table of Contents

Why are we upgrading?

Keeping the scripts.mit.edu servers secure is one of the most important things that the team works on. This includes not only careful design and review of the custom software that we run, but keeping up to date with security patches for Fedora, which is the distribution of Linux that we run. Fedora's security support for Fedora 9 will end on July 10, and so we will be upgrading to Fedora 11 which will continue to receive security support for approximately another year.

Will I need to do anything to my website?

We expect that for the vast majority of our users, the upgrade will be very smooth, your applications will work with no changes, and you won't have to do anything. However, we strongly encourage you to test your website as soon as possible. Also, check the list of known issues to see if you are likely to experience any problems we're already aware of. In particular, it is very important that you test your site soon if you rely on Python 2.5 code that may not run with Python 2.6.

How will the upgrade work?

Sometime on Thursday, July 9, three scripts.mit.edu servers running Fedora 11 will be added to the load-balancing pool, and simultaneously the three current Fedora 9 servers will be removed from the pool. Over the course of the next few days, additional Fedora 11 servers will be set up and made available.

Will there be a service outage?

We do not expect there to be any service outage. Our plan is to simultaneously add three Fedora 11 servers to the load-balancing pool and remove the Fedora 9 servers. If your website and scripts work with our Fedora 11 testing server, they should work and be available to your visitors continuously throughout this process.

Are you making any other improvements to the service at this time?

Yes! There are several improvements underway.
  • We're adding more hardware: instead of three physical servers, we will soon have four of them.

  • We're adding more RAM: we have already begun the process of upgrading the RAM in our servers, and will be continuing to do so through the Fedora 11 upgrade. Each of the servers will have between 12GB and 16GB total of RAM.

  • We're adding more webservers: until recently, scripts.mit.edu had two real hardware servers, each with 4GB of RAM. We have reached the point where this is no longer sufficient to handle the requirements of all of our users. For the past month and a half, we have also had a third server running as a virtual machine. This experiment has gone quite well, and has nearly eliminated the server crashes we were experiencing due to load. Once the upgrade is complete, all the scripts.mit.edu servers will be virtual machines, and there will be 8 of them with at least 6GB of RAM each, spread among 4 hardware hosts.

    Note: You should never hardcode the names of the servers into your scripts, because the servers in the load balancer pool may change at any time. You can see a list of which servers are in the pool updated in real time at http://scripts.mit.edu/servers

How do I test my website?

There are several options available to you.

Note: If you are running an application that asks you to upgrade it when you use our testing server, do not perform the upgrade until July 9. If you do, your site will most likely work on the testing server, but no longer work on the production Fedora 9 servers. If you do perform an upgrade, you will most likely have to restore a backup of your database and/or application. If you wish to test your application sooner, you may wish to make a new copy of it that uses a different database. One application that has this problem is Trac. It does appear to work fine on Fedora 11, but if you upgrade your Trac now, it will stop working on the production servers.
  • On any Athena workstation, you can log in and run these commands (make sure you do not have a web browser open first):

    athena% add scripts
    athena% firefox-test

    This will start Firefox for you with special configuration that ensures that any website you visit that's hosted on scripts will be retrieved from our test server. You can then try using all the features of your website just as you ordinarily would. Note that this will be using your real website; it is not a separate copy of your site.

    This configuration will only be used while you have that copy of Firefox open. If you close it and run Firefox normally, you will no longer be using our test server.

  • If you currently use a URL like 
    http://scripts.mit.edu/~yourLockerName/siteName
     and it does not do any fancy redirection or mangling of the URL, then you can simply visit 
    http://scripts-test.mit.edu/~yourLockerName/siteName
     instead. Note: Several web applications, including WordPress, change the URL on you - once you click any link from the front page of a WordPress installation, you will no longer be using the test server. If you have such an application, you will need to use one of the other testing methods.

  • If you visit the SIPB office (W20-557), there are a few specially labelled workstations there which always use the scripts testing server. You do not need to do any special configuration to test your site on these machines. Feel free to come by SIPB any time we're open (the office doesn't have fixed hours, but is open most afternoons and evenings; feel free to call 617-253-7788 to check if we're open before coming over) and test your site on these machines.

  • If you use Linux, or a similar operating system, and are comfortable with system administration tasks, you can temporarily configure your system to use our testing server by adding a line to your /etc/hosts file that maps the hostname your website uses to the IP address 18.181.0.229. Note that your website might use any of these hostnames: 
    scripts.mit.edu, scripts-cert.mit.edu, yourLockerName.scripts.mit.edu
     or something like customname.mit.edu. Be sure that the line you add to your /etc/hosts uses the correct name, and be sure that you remove that line when you are done testing. If you are on a Windows system, the analogous file is 
    C:\Windows\System32\drivers\etc\hosts

May I ssh into the test server?

Yes, anyone with a scripts account may ssh to scripts-test.mit.edu, just as you ordinarily would ssh to scripts.mit.edu, if you would like to use a shell.

What if my site doesn't work?

First, check the list of known issues. We'll update that list as we learn of new issues, and will keep it up to date with the status of our investigation and ways that you may be able to work around the problem.

If you're unable to figure out what's wrong, you can e-mail us as always at scripts@mit.edu, and we'll do our best to help you figure it out. If you'd like in-person help, you can come to our office hours.

When are your office hours?

Check back here to see updates for when we'll be holding office hours each week. Since many of our users are students, and many of our users work at MIT, we'll try to hold some of them during business hours, and some at night.
  • Week of June 14 - June 20
    • Thursday, June 18, 6pm-10pm in W20-557
  • Week of June 21 - June 27
    • Tuesday, June 23, 10am-12pm4pm-6pm in W20-557
    • Wednesday, June 24, 8pm-10pm in W20-557
  • Week of June 28 - July 4
    • By request
  • Week of July 5 - July 11
    • Thursday, July 9, 5pm-8pm in W20-557

What are the known issues at this time?

  • Python has been upgraded to version 2.6.

    • If you have a custom module installed in 
      lib/python2.5/site-packages
       in your locker, you'll need to install it in 
      lib/python2.6/site-packages
       as well.

    • There are some small code incompatibilities between Python 2.5 and 2.6. If this causes a significant number of problems for our users, we will look into trying to make Python 2.5 available as well. Please contact us if you are affected by this.

  • CherryPy version 3.1.1 is installed on Fedora 11, but contains a bug that causes it not to work with Python 2.6. This bug was fixed in CherryPy 3.1.2. We have filed bug 506367 with Fedora to upgrade the package, and they are in the process of doing so.
    CherryPy has been upgraded to version 3.1.2 in Fedora 11.

  • Trac, which you may have set up with our autoinstaller, will ask you to run commands to upgrade it. Do not run these commands, or your Trac will stop working on the Fedora 9 servers. Trac seems to work fine in Fedora 11; we recommend that you wait to perform the upgrade until our upgrade on July 9.

How can I stay up to date on news about Scripts?

News about scripts.mit.edu is posted to our blog periodically. Important announcements are e-mailed to the scripts-announce mailing list. If you're not already signed up for the list, please take a moment to do so by clicking the link above. 
Last updated $Id: scripts-f11-transition.html,v 1.15 2009/07/09 21:31:41 mitchb Exp $

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