There are many others but these are just a few off the top of my head and I’m still discovering what other capabilities Varnish has. The site has not gone live yet so I’m still testing on a dev version of the site and have not had an opportunity to perform any load testing yet. So far with my current working configuration I’ve made the following tweaks

The use of mod_expires on the Apache backend controls cache times for static assets (css,js,images,etc..). In my googling around when reading about Varnish I see a lot of people are setting cache times in their VCLs. IMO you should be letting the backend or application itself control the TTLs on objects. Within your application you can set more defined TTLs for certain sections of your site or even certain types of dynamic content without having to rely on complex VCL rules or deal with the deployment of the rules into Varnish. While Varnish does support a “graceful” style restart, its not quite as eloquant as doing service apache graceful. Kristian Lyngstol (one of the Varnish devs) has a good post on his blog on dealing with this. Also with the use of mod_expires you can set TTLs based on MIME-type within Apache.

One other thing I see a lot of people blindly recommending in configurations to deal with Varnish’s behavior of not caching cookies is to take the cookie value and add it into Varnish’s hash of the object. e.g.

If a light bulb just went off in your head as to why this is a bad idea, kudos to you. What you’re basically doing is creating a cache per-user on your Varnish server. Your hit ratio will plummet from this config. There are scenarios where this can be used in a good way. In talking with some folks in #varnish on irc.linpro.no, a scenario where you’d want this is if say you had a cookie that was a display filter on your site or some sort of site customization that didn’t have a large number of combinations.

One thing that bothers me about Varnish currently is that it’s admin interface is completely unsecured. By default it listens on localhost but without any authentication, anyone with a shell on your Varnish box can bring down your Varnish instance or modify the config in anyway they feel fit. For those that allow dev’s on production servers to debug logs, this is a bit of a security concern. I’m not really sure of a workaround for this, so if anyone has any ideas, leave it in the comments below.

If you use Cacti for trending, there are some great templates available over at the cacti forums. They utilize a python script that needs access to the admin interface.

I’ll probably post some more in the future on Varnish as I do further reading and testing with it.

My first project I decided to tackle as I go through my book is writing a module that will fetch stock quotes from Yahoo’s Finance page and store them in memcached.  I just pushed it out to github available @ http://github.com/jlintz/python_quote.  I’m hoping to get some feedback from some people on where I can improve in my code and hopefully it will be useful to someone else out there.  As I go through the book I plan on going back and looking at the code and see what I can refactor and I’m sure along the way I’ll probably re-architect things.

One thing I know I need to do is write some unit tests for the module.   When I was in my Computer Science program in college, we really never had any exposure to unit tests.  The unit tests consisted of assert statements and really never had any real lessons on them.  I need to do more reading on unittest.  I know many developers write their unit tests first before writing a single line of code in a test driven development approach.  It’s something I want to look at more and see if I should consider picking that up.

Also as part of this coding project, it was a good excuse to get some exercise with Git.  It’s pretty easy to work with and I haven’t even scratched the surface of its potential.  I just need to begin looking at some of its more advanced features and incorporating them into my work flow.

Vim is another program I’m getting some finger exercise in.  When I started my job 3 years ago I had never really opened Vim/Vi but one day forced myself to learn it because as a sysadmin, Vi will always be there for you, like your friend Stewie.  In my day to day uses of Vi, I just used the basics, hjkl and :wq.  Slowly I picked up some commands from co-workers and got used to using them daily.  When writing code in Vim , there are a lot of tricks and commands to aide you in writing code , I’ve read about many but now it’s a matter of incorporating them so I don’t have to think much and breaking my old habits to use the new commands I’ve read about.

I got a new 1TB hard drive for the holidays and I had been meaning to redo my setup for some time and finally took the plunge this weekend.  I also decided I was going to give Windows 7 a go.  With my current(now old) setup, I couldn’t install iTunes in Windows XP 64bit so I had to do all my iPhone syncing using a 32bit Windows XP install inside a Virtualbox VM inside of Ubuntu.  I would run into issues anytime I would have to do a firmware upgrade on my iPhone since the iPhone would disconnect from the VM during the firmware upgrade process and the USB filters I had in place to pass through the iPhone to the VM would run into a race condition with the OS while it tried to mount the iPhone as a photo device.  This would end up leaving my iPhone as a brick (but upgraded) and I’d have to restore from backup and re-sync all my music, a process that would take up to 4 hours.  The last time I did an iPhone upgrade, I learned my lesson and did the upgrade from a Mac, no restores needed and I didn’t need to do any syncing after.

With my new setup I was planning on doing all of my syncing in Windows 7, without having to worry about any issues with USB pass through or performance issues of doing the sync through a VM.  Once I got my Windows 7 install up and running, I installed iTunes and added my music to the library.  I went to go ahead and perform my first sync and noticed it began syncing then about 5 seconds later it would just finish.  I tried this a couple more times and noticed it was still not behaving right.  I figured I’d try to atleast backup my iPhone incase anything went wrong.  I began the backup process and went to go play some CoD MW2.  I came back an hour later and noticed no real progress on the backup of the iPhone.  I cancelled the backup process and then tried restarting the backup.  I let it sit for a couple of hours and it never completed.  Normally a backup will take maybe 10-15 minutes so I knew something was wrong.

I began Googling and right away I came upon this thread on the Apple forums.  The thread described a varying amount of issues with Windows 7 64bit and iTunes syncing.  Issues with people having their iPhone not recognized to certain chipsets causing sync issues.  I tried jumping around the thread a bit looking for some simple answers related to my issues, but most of the solutions were geared towards BIOS updates.  After some more Googling I found a thread on one of the MS support forums (sorry I lost the link) where a representative from MS was actually contributing to the thread and seemed to be working with developers on a hot fix for the issues.  The thread talked about users with issues with USB hard drives and iPhone issues as well. Later in the thread MS eventually came up with a hot fix for the issue so I figured I’d give it a go.  The hotfix can be found here http://support.microsoft.com/kb/976972 .  I installed it and low and behold, it actually fixed my issue.  This is the first time I can remember downloading a hotfix for an issue I’ve had with Windows and it actually fixing the problem.  I’m now finishing syncing up my music to my iPhone which is syncing A LOT faster than going through a VM layer.  Hopefully someone will stumble across this blog post facing similar issues and it will solve their iTune woes.

As I’ve come to realize with Apple products, they always seem to leave out the most obvious of features to people and dictate to the user what their experience and usage of their products should be. A couple quick examples off the top of my head, you cannot turn off the monitor on the iMac, iTunes doesn’t support the ability to monitor your mp3 folder for changes in the library (iTunes 9.0 did a weak attempt of supporting this by adding a folder you can drag things into).

Apple does seem to be listening…. a bit, to their users with the iPhone as everyone is so vocal about them and it’s one of the most widely used phones out there. I remember in the past if I had any issue with my flip phones there would almost certainly never be any firmware release to fix the issue and the product would be abandoned all together by the company within a year. Calling support about the issues was pointless, they would just try sending you a replacement phone or just file a bug report that never got corrected unless there were enough people using the phone to complain about the same issue (there never was). I just accepted that as the norm if you were not using the most popular phone out on the market at the time. Then I got an iPhone and all of a sudden I started caring about my phone working perfectly. All those little nuisances suddenly needed to be fixed dammit, I paid a lot for this phone!  A few things still remain that I’d love to see get fixed/added as an option in 3.2…

1. Timestamps on all text messages sent and received.  Currently you only get a time stamp on a message if it’s the first message that’s been sent after 15(or some other time) minutes of inactivity.  The data is definitely there, but they are choosing not to display it for whatever reason.  Makes them look sleeker? F that, just give users an option to turn them on and off.  Friends text me all the time saying “I’m on my way” and I always used to use that to judge how long its been since I’ve heard from them.
2. A global option to turn off auto-rotate.  A couple of apps have this built in currently, mainly e-book readers.  I, like many other people, use their iPhone in bed, or laying on the couch and end up turning on our sides only to have the current item we are reading rotate along with us.  I then end up trying to play a game with the phone on how I can move it slow enough not to trigger a rotation and still be able to read what I wanted to while laying on my side.
3. Video and Podcast titles are cut off that are too long.  If you download any podcast or video with a title more than 11 characters long, it is truncated on the listing.  Guess what?  Every single video and podcast I’ve come across has a title longer than that.  The first few words in every video and podcast title appear to rarely have any information relevant to the episode you are wanting to watch.  I can never find particular episodes of videos or podcasts because of this, unless I happen to know the date of the item.  Please just give us some sort of way to scroll horizontal in the title box to see the rest of the title.
4. An accurate signal strength indicator.  I’m not sure if this falls in AT&T’s lap or not, but my phone seems to have either 2 states, full bars or no bars, and there are countless times when I have full bars that I can’t make a phone call, send a text or get any data service, but the indicator does not change.
5. Ok this one is a stretch but…. The weather icon always says 73 and sunny and I’m constantly fooled into thinking that’s the actual weather outside.  It seems like the iPhone supports dynamically changing the app icons as it can add a progress meter during an install and an unread message counter for apps with inboxes/notifications.  It would be nice if the weather icon could dynamically change instead of mocking me all the time.
6. Edit 12/09/2009: Would like to see the ability to snooze Calendar events that go off, and also have them accumulate with a count on the calendar icon for unread events that have gone off.
7. Ability to select “Emergency” contacts on your phone to call if phone is locked.  I lock my iPhone and in the event of an emergency or if I lose my iPhone and some good samaritan happens to stumble upon on it, I’d like the ability to choose a few emergency contacts that can be displayed without having to unlock the phone that can be contacted in an emergency or to return my phone.