Archive for March, 2009
Virtual instances running in Amazon’s EC2 service have several ephemeral disk drives that can be used for temporary storage (temporary because they are not persisted as part of the AMI). Recently, I had to figure out exactly when those drives were mounted and available during boot. The specific issue I was seeing was that I had registered some services to start automatically during boot, and those services started software packages that relied upon the ephemeral drives. This is on Windows 2003 Server, by the way; this is a non-issue on Linux, where mounted drives precede the init sequence for application level processes.
Through some trial and error (and I’ll abridge the details here), I was able to determine that the ephemeral drives are ready in all respects after the following two services have started: Ec2Config and Virtual Disk Service (vds). It was a simple matter of creating service dependencies for my registered services to ensure that they started after Ec2Config and VDS were started, and that fixed the glitch. I was using cygwin so I was able to use the
cygrunsrv command to create the dependencies (via the
--dep argument). People with more Windows kung fu would probably use
regedit to do the same thing.
Hope this helps.
Last week, I needed to configure a Windows 2003 AMI in EC2 to run lighttpd with SSL. Once again, a simple job that I thought would be quick and painless turned into an extensive hacking session. Here is a quick roadmap of what I did.
My initial thought was that there must be a native port of lighttpd with SSL support for Windows…wrong again! I don’t know why I continue to think that open source projects will be ported to Windows; Linux is long since mature enough that people can use it directly, rather than porting open source Linux software to Windows.
In any event, cygwin lists lighttpd in its package list, so I was left with the option to run lighttpd via cygwin. A few quick clicks of the cygwin installer gave me lighttpd 1.4.20-1, all installed and ready to start. I dropped in a lighttpd.conf file containing ssl.engine declarations and started the server. Lighttpd promptly informed me that SSL support had not been compiled in.
I really have no idea why lighttpd on cygwin ships without SSL support compiled in, especially since the openssl libraries are available within cygwin and SSL support can be compiled in with just a simple option to ./configure. But, I should just be able to download the lighttpd source and compile it myself, on cygwin, with SSL support enabled, right?
Wrong again! After downloading lighttpd source for 1.4.20 and installing gcc on cygwin, I ran ./configure with the following options:
./configure --disable-shared --enable-static --prefix=/usr --with-openssl
I kicked off the build with make, and went to grab a beer (the build proceeds very slowly). When I returned, I found the build had failed with a symbol undeclared error for EAI_SYSTEM. This error has lots of search hits and some hacking-oriented solutions, but none of those solutions seemed to work for me, owing to conflicts between the static build of lighttpd and the main cygwin DLL. Even when I did manage to get the build to successfully complete, I found that some features (e.g. CGI execution) just didn’t work. The last thing I want is a flaky build of lighttpd running within cygwin on Windows, so I needed a plan B.
After a few more searches, I came across the WLMP project. WLMP has a standalone build of lighttpd — optionally bundled with MySQL and Php — that includes the cygwin DLLs but doesn’t otherwise require or run within cygwin. Funky, but promising. I installed the lighttpd-only version of WLMP, and I was able to bring lighttpd up with support for SSL, but only as a stand alone application, outside of cygwin. If I tried to run it from within a cygwin shell, or even with the cygwin DLL loaded, I found all sorts of silent errors without any messages. I intended to use cygwin extensively while lighttpd was running, so this was a significant problem.
On to plan C. I’m starting to think this isn’t going to happen when it occurs to me that the WLMP lighttpd build is a cygwin build with some conflicting cygwin files. If I download a version of WLMP that uses the same lighttpd 1.4.20 version as cygwin, and remove the files that conflict, then maybe I can get the WLMP build to run in cygwin. It’s worth a shot, right?
After some trial and error, I was able to make this work as follows:
0) Download WLMP lighttpd 1.4.20, matching the version of lighttpd in cygwin.
1) Delete the Cygwin1.dll file from the WLMP lighttpd directory
2) Add execute permission to all of the DLLs in the WLMP lighttpd directory, and all of the mod DLLs in the WLMP lighttpd/lib directory.
3) Cd into the WLMP lighttpd directory, and from within the WLMP lighttpd directory start lighttpd with the following command:
./lighttpd -V -m /usr/lib/lighttpd
If all went according to plan, you should see the list of features compiled into lighttpd, and there should be a “+” sign in front of “SSL Support”. My next test was to start lighttpd with the same –m argument, and using my lighttpd.conf with the SSL configuration, and it worked flawlessly without any cygwin conflicts.
I can’t tell you why the current directory (within the WLMP lighttpd directory) is important in getting this hack to work. My guess is that the WLMP version of cygwin is using a combination of DLLs from the standard cygwin lighttpd lib directory in /usr/lib/lighttpd and the WLMP lighttpd lib directory in the current directory, and somehow this combination works without cygwin DLL conflicts in this particular situation. Who knows? All I can say is that it would have been really nice if the cygwin folks had enabled SSL support in their build of lighttpd…
Anyway, that’s it. Hope that helps.
- Siri – a Shot Across Google’s Bow
- “Is colocation cheaper than using a cloud computing service to run the same workload?”
- “How Big is Amazon’s Cloud Computing Business?”
- “Android will run majority of smartphones by Spring”
- Amazon EC2 I/O Performance: Local Ephemeral Disks vs. RAID 0 Striped EBS Volumes
- “We create 5 exabytes every two days.”
- “Go Screw Yourself, Apple.”
- “You are not Google. (or: you don’t really need NoSQL…)”
- “The largest cloud providers are botnets.”
- Observed Performance of Amazon EC2 Instances
- Cloud Computing and Mobile Devices
- Time and Clock Issues in Windows-Based EC2 Instances
- My experimental local and real-time search engine is now available
- Entropy in Cloud Computing Applications
- How to Jailbreak iPhone 3.01