futureal - Developer IT

Managing Many External Hosts Using EC2 and Route 53

- by futureal

Looking for a "best practice" answer to managing externally-addressable hosts using the combination of Amazon EC2 and Amazon Route 53, without using Elastic IPs for each host. In my scenario I will have 30+ hosts that need to be accessible from outside EC2, so directly using internal DNS will not work. In the past, I have addressed hosts by assigning an elastic IP to that host (let's say, 55.55.55.55) and then creating an associated A record. For example, let's say I want to create "ec2-corp01.mydomain.com" I might do: ec2-corp01.mydomain.com. A 55.55.55.55 300 Then on that EC2 instance, I would assign the Elastic IP of 55.55.55.55, and everything works fine. Of course, to make this work, I need to have one Elastic IP per instance, which is something I'd like to avoid if possible; I'd like the infrastructure to be more dynamic. So my thought is to try something like: Create a script that queries the internal EC2 tools to determine an instance's private hostname On instance boot, call that script to determine its hostname, and then using the command-line Route 53 interface to find and update that hostname to its current internal hostname Since the host will have a relatively low TTL (let's say 300 as above, or 5 minutes) it should take effect pretty quickly Is this a good idea? Is there a better or more widely accepted way to handle it? If it IS a good idea, what type of record should I be creating? A CNAME that points to the internal host, like ec2-55-55-55-55.compute-1.amazonaws.com? Is an A record better or worse? Thanks!

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Performance Tuning a High-Load Apache Server

- by futureal

I am looking to understand some server performance problems I am seeing with a (for us) heavily loaded web server. The environment is as follows: Debian Lenny (all stable packages + patched to security updates) Apache 2.2.9 PHP 5.2.6 Amazon EC2 large instance The behavior we're seeing is that the web typically feels responsive, but with a slight delay to begin handling a request -- sometimes a fraction of a second, sometimes 2-3 seconds in our peak usage times. The actual load on the server is being reported as very high -- often 10.xx or 20.xx as reported by top. Further, running other things on the server during these times (even vi) is very slow, so the load is definitely up there. Oddly enough Apache remains very responsive, other than that initial delay. We have Apache configured as follows, using prefork: StartServers 5 MinSpareServers 5 MaxSpareServers 10 MaxClients 150 MaxRequestsPerChild 0 And KeepAlive as: KeepAlive On MaxKeepAliveRequests 100 KeepAliveTimeout 5 Looking at the server-status page, even at these times of heavy load we are rarely hitting the client cap, usually serving between 80-100 requests and many of those in the keepalive state. That tells me to rule out the initial request slowness as "waiting for a handler" but I may be wrong. Amazon's CloudWatch monitoring tells me that even when our OS is reporting a load of 15, our instance CPU utilization is between 75-80%. Example output from top: top - 15:47:06 up 31 days, 1:38, 8 users, load average: 11.46, 7.10, 6.56 Tasks: 221 total, 28 running, 193 sleeping, 0 stopped, 0 zombie Cpu(s): 66.9%us, 22.1%sy, 0.0%ni, 2.6%id, 3.1%wa, 0.0%hi, 0.7%si, 4.5%st Mem: 7871900k total, 7850624k used, 21276k free, 68728k buffers Swap: 0k total, 0k used, 0k free, 3750664k cached The majority of the processes look like: 24720 www-data 15 0 202m 26m 4412 S 9 0.3 0:02.97 apache2 24530 www-data 15 0 212m 35m 4544 S 7 0.5 0:03.05 apache2 24846 www-data 15 0 209m 33m 4420 S 7 0.4 0:01.03 apache2 24083 www-data 15 0 211m 35m 4484 S 7 0.5 0:07.14 apache2 24615 www-data 15 0 212m 35m 4404 S 7 0.5 0:02.89 apache2 Example output from vmstat at the same time as the above: procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 8 0 0 215084 68908 3774864 0 0 154 228 5 7 32 12 42 9 6 21 0 198948 68936 3775740 0 0 676 2363 4022 1047 56 16 9 15 23 0 0 169460 68936 3776356 0 0 432 1372 3762 835 76 21 0 0 23 1 0 140412 68936 3776648 0 0 280 0 3157 827 70 25 0 0 20 1 0 115892 68936 3776792 0 0 188 8 2802 532 68 24 0 0 6 1 0 133368 68936 3777780 0 0 752 71 3501 878 67 29 0 1 0 1 0 146656 68944 3778064 0 0 308 2052 3312 850 38 17 19 24 2 0 0 202104 68952 3778140 0 0 28 90 2617 700 44 13 33 5 9 0 0 188960 68956 3778200 0 0 8 0 2226 475 59 17 6 2 3 0 0 166364 68956 3778252 0 0 0 21 2288 386 65 19 1 0 And finally, output from Apache's server-status: Server uptime: 31 days 2 hours 18 minutes 31 seconds Total accesses: 60102946 - Total Traffic: 974.5 GB CPU Usage: u209.62 s75.19 cu0 cs0 - .0106% CPU load 22.4 requests/sec - 380.3 kB/second - 17.0 kB/request 107 requests currently being processed, 6 idle workers C.KKKW..KWWKKWKW.KKKCKK..KKK.KKKK.KK._WK.K.K.KKKKK.K.R.KK..C.C.K K.C.K..WK_K..KKW_CK.WK..W.KKKWKCKCKW.W_KKKKK.KKWKKKW._KKK.CKK... KK_KWKKKWKCKCWKK.KKKCK.......................................... ................................................................ From my limited experience I draw the following conclusions/questions: We may be allowing far too many KeepAlive requests I do see some time spent waiting for IO in the vmstat although not consistently and not a lot (I think?) so I am not sure this is a big concern or not, I am less experienced with vmstat Also in vmstat, I see in some iterations a number of processes waiting to be served, which is what I am attributing the initial page load delay on our web server to, possibly erroneously We serve a mixture of static content (75% or higher) and script content, and the script content is often fairly processor intensive, so finding the right balance between the two is important; long term we want to move statics elsewhere to optimize both servers but our software is not ready for that today I am happy to provide additional information if anybody has any ideas, the other note is that this is a high-availability production installation so I am wary of making tweak after tweak, and is why I haven't played with things like the KeepAlive value myself yet.

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Capture Outgoing Email to One Mailbox or Account on Linux

- by futureal

I am looking to see if anything exists that would allow us to capture all outgoing email on a machine -- for example, in a staging environment -- and drop it in a single place, which ideally would be something we could check with a mail client. Currently we're doing this on the software level (if environment is staging, rewrite address) which is a bit ugly and leads to errors. The servers are currently on Debian Linux, using exim as the mail transport. Open to any and all suggestions!

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RadioButtonGroup with each RadioButton added in components?

- by futureal

Hi, Working in Flex 3, I have a series of components being rendered on a canvas, each of which should represent a single potential selection, ideally in a RadioButtonGroup. So in my parent canvas I am defining the RadioButtonGroup, and each component provides a single RadioButton. However, this doesn't seem to work. Suppose there is a component called aComponent defined as such: <mx:Canvas ...> ... <mx:RadioButton id="someButton" groupName="myRadioButtonGroup" ... /> </mx:Canvas> The outer canvas: <mx:Canvas ...> ... <mx:Script> public function doesSomething():void { var myComponent:aComponent = new aComponent(); outerCanvas.addChild(myComponent); } </mx:Script> ... <mx:RadioButtonGroup id="myRadioButtonGroup" /> </mx:Canvas> So my guess was that at this point if, say, four of these components were added, the radio buttons would behave in mutually exclusive fashion and I'd be able to access myRadioButtonGroup.selectedValue to get the current selection. However, it doesn't seem to work that way. Is what I'm trying to do even possible, or have I maybe just missed something? Thanks!

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