Why isn’t Apache on CentOS on a Rackspace Cloudserver Working?

Damnit, this one catches me every time.  I setup new cloudserver instances so infrequently that it never hits muscle memory.  Open up that damn firewall port 80!

Edit /etc/sysconfig/iptables:

vi /etc/sysconfig/iptables

Add the following line

-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT

Save and restart iptables.

service iptables restart

I’m not sure if it is CentOS or Rackspace that is locking down the instances. I do know that I don’t have to do this for my local CentOS machines.

SMF: Solr

Setting up Solr was a bit different then the others. Solr’s distribution is multifaceted, containing multiple server examples, client code, as well as, a simple production ready server. So let me start off with a few steps I took in setting up Solr.
<Read on…>

Troubleshooting SMF Service Startup

As I was working on my SMF scripts for the migration from Linux, I found some fancy ways to trace what was happening with a service that failed to start with new configuration.

There is a command called truss which allows you to follow along as something is being executed. See: man truss.

What I found really cool is that you can modify your existing SMF script from the command line. No need to make changes to xml and then reimport.

So back to the tip, if a service isn’t starting and you have eliminated all of the other possibilities with configuration, you need to see what the service script is doing. In my case, I was having a hell of a time with Red5. So here is what you can do:
<Read on…>

SMF: Red5

Red5 is the open source answer to Adobe’s Flash Streaming Server. I use it not for streaming, but for recording audio and video from a user’s web browser. Yeah, that is a really cool feature if you have the need for it.

It turns out that the Red5 team actually created an SMF configuration. However, you have to download the source to get to it. I was half way through my own before I saw the change entry on the Red5 commit mailing list. However, it used some funky paths. I took this and fixed it for my Joyent specific installation.
<Read on…>

SMF: Tomcat

For my Tomcat SMF setup, I have two files.  One, the configuration for SMF.  The second is the script used to start and restart tomcat. (My stop is simply a kill. Unfortunately, there are a few threads that aren’t shutting down properly.)
<Read on…>

Why is SSH so Slow?

I was having a horrendous time logging into one particular Linux server.  It would take anywhere from 20 seconds to a minute to let me log in.

Turns out, there are two sshd config settings you should pay attention to:

VerifyReverseMapping and GssAuthentication

The latter only really helps if you are connecting from a Mac (like me).  VerifyReverseMapping will tell the server to look up the host name for client IPs, and if the IP you’re SSH’ing from doesn’t have a reverse DNS entry, this will result in a DNS timeout.  (The source of most of the delay in logging in.)

So open up your sshd config file: /etc/ssh/sshd_config

Remove VerifyReverseMapping, if it exists.  The default value for it is no.  If you don’t see it, this isn’t the source of your problem.

Remove GssAuthentication, if it exists.  It also, defaults to no.

Solaris Service Management Facility

Leading in with my post on switching from Linux to OpenSolaris, there are quite a few things I am in love with on OpenSolaris.

Since my first real world exposure to OpenSolaris is the process of migrating web applications away from Linux, the first thing I really had to get familiar with is the Service Management Facility framework.  SMF for short.  SMF is the Solaris equivalent of UNIX/Linux init.d, Apple’s launchd, or Windows services.

I’m coming from a decade long Linux background so let me compare and contrast init.d and SMF. <Read on…>

Linux to Solaris

It was 3 in the morning. I just got one of the pages (well, now text messages) that you dread. Site’s down. Shit. This is the 4th unexpected “Availability Event” in the past 6 months. What is it now?

I fire up the grid control panel on my laptop. Well, try to. The browser is just spinning. Grrr. Let’s see if I can SSH into the grid controller. Nope, just spinning there too. What the heck man? All the websites and applications are down. You’ve got to be kidding me!

I fire off a quick helpdesk ticket and then call the emergency line for our guys.  Leave a voicemail.  Get a callback in 5 minutes from them.  Hmm, they are awake already?

John Doe:  ”Mike, just calling you back.”
Me: “What’s the story?”
John Doe: “Yeah, well you see, the Data Center is doing network maintenance.  And we just got the email 20 minutes ago, ourselves.”
Me: “?!??!?!!”
John Doe: “Yeah, that’s what we said.  There is nothing we can do but wait it out.”

You know, this one wasn’t their fault.  But it was the last straw.  It is time to cut our losses and run.  RUN!

<Read on…>