Web Site Performance Monitoring Tools: Load Testing

Determining the performance of web site and web applications is important. In order to create sites users want to visit they need compelling content but they also need to provide the performance users expect.

One of the wonderful aspects of creating web applications is the availability of software as a service solutions to meet your needs. These include monitoring tools and tools for testing the performance of your sites.

Image of LoadView testing - $9.99/mo + load test costs of each test

In this post I look at load testing using LoadView Stress Testing service. Tests are not cheap. The cost is $9.99 a month for an account plus the costs of each stress test you run. The next image shows the breakdown of a small stress test on this blog which cost $8.25 to

image of a small load test cost breakdown ($8.25 total)

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Locking and Unlocking a User in Ubuntu

To lock a user in Ubuntu sudo usermod –expiredate 1 [username] Substitute the user’s username where username is shown below.

sudo usermod --expiredate 1 username

This also can be shortened to

sudo usermod -e 1 username

To unlock a user

sudo usermod -e -1 username

This will disable the user both from accessing via password and from accessing via a private key.

You can also expire a user at a future date using

sudo usermod -e YYYY-MM-DD username

To expire a password and force a user to enter a new password

sudo passwd -e YYYY-MM-DD username

Related: Managing Users in UbuntuReset Root Password on MySQL DatabaseDon’t Copy-Paste Directly from Website to Terminal

How to Manually Run Cron Tasks

To manually run cron tasks you can use the run-parts command in Linux.

So to run your cron-weekly, for example, to test that a fix you just made runs without error (this is what I just did, in fact)

run-parts /etc/cron-weekly

run-parts will run all the executables in a directory (you must point at the directory). So if you have several files in cron-weekly to run, you can’t just point to one of the files.

You may run into environmental differences running the script as a different user than the cron test runs at, so you can run as that user if needed. You need to be aware this is a quick and simple way of testing part of the process but it doesn’t do a perfect job of testing if it works as a cron task. But it will let you catch some failures quickly and fix them in time for the actual cron task to run. So do check that the everything works after the real cron job runs.

This is just the kind of thing I said I would put in this blog. Simple stuff but things I forget – so I put it here to remember and maybe help out others, like me, that need really basic tips.

If you have a cron task item (or have setup the whole task this way) that is just a script and you just want to test that 1 item you may run the script directly. For example (for a Linux shell script):

sh /etc/cron.weekly/your_crontask_script.sh

Related: Updates Needed When Upgrading from Apache 2.2 to 2.4Rsync to copy Files Between Servers and ComputersBash Profile Adjustments for Scrolling HistoryChecklist: Setting Up a New Domain on VPS

Chrome Remote Desktop

I am more often frustrated by Google the last few years that pleased with them. But they do still provide some pretty awesome tools. For example, Chrome Remote Desktop lets you access a computer over the internet (and lets you to allow another user to access your computer securely over the internet).

Chrome Remote Desktop allows users to remotely access another computer through Chrome browser or a Chromebook. Computers can be made available on an short-term basis for scenarios such as ad hoc remote support, or on a more long-term basis for remote access to your applications and files.

screen shot of chrome remote desktop

Chrome Remote Desktop is fully cross-platform. Provide remote assistance to Windows, Mac and Linux users, or access your Windows (XP and above) and Mac (OS X 10.6 and above) desktops at any time, all from the Chrome browser on virtually any device, including Chromebooks (including Android phones and iPhones). The iPhone app is new.

Some users worry about installing such an app given all the spying and hacking scandals. That is not a completely crazy worry. Google, and others, have been taking advantage of weak user control (and even bugs and work arounds to avoid stated user preferences) to track users and use that information to make money selling ads. With many cool and useful tools there are risk of them being misused. And practices of governments and huge corporations have been so egregious to give a sensible person pause. Still in the right situations this is a pretty cool looking tool (similar things exist but the combination of price [this being free] and simplicity make this interesting).

Related: Chrome Remote Desktop support forumUsing scp (secure copy) to Copy Files Between ComputersUsing Rsync to copy Files Between Servers and ComputersLinux/Ubuntu File and Directory PermissionsGovernments Shouldn’t Prevent Citizens from Having Secure Software Solutions

Compare WordPress Files on Server to Proper WordPress Version

Sadly one of the hassles in managing your own WordPress blog is dealing with people that use your blog to serve spam content. These hacks can insert spam links into your pages and posts or create spam directories that are completely their own content on your domain.

There are many issues to deal with in re-establishing control of your server; but that isn’t the scope of this post.

This is just a tips if you are troubleshooting to try and determine what is going on. Often your server has been hacked to allow uploaded php pages to be added or for WordPress php files to be edited.

One way to track down if the files have been changed or new ones added is to compare the WordPress files on your server to the current files for a fresh WordPress install. This assumes your blog is using the current version, which hopefully it is because on the big improvement WordPress made is to make those updates automatic. That greatly reduces the chance to have WordPress be the vector to infecting your server. If you were using a older version then just compare to the field for that version from the WordPress server.

If you don’t have a current backup I would make a backup before I tried this. Obviously, don’t make any deletions or changes to your server unless you understand what you are doing. You can create big problems for yourself.

You can use the diff command to view the difference between WordPress on your sever and the fresh install from WordPress. I install the new WordPress in a new directory outside public_html. At the cli on a Ubuntu/Linux server:

sudo wget http://wordpress.org/wordpress-4.0.zip
unzip wordpress-4.0.zip
diff -rq wordpress ../public_html/

wordpress-4.0.zip – replace with whatever the version is you are using.
../public_html/blog/ – replace with the path to your blog

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Updates Needed When Upgrading from Apache 2.2 to 2.4

I updated from Ubuntu 12.04 to Ubuntu 14.04 on a virtual private server.

When you do that update, Apache is updated from 2.2 to 2.4. Certain changes mean that until you update the site-available configuration files no web sites will work.

The quick checklist of what you have to do for each configuration

  1. update the file to add or edit the directory details (where /var/www/curiouscatnetwork.com/public_html/ is the path to the website files on your server)
    <Directory /var/www/curiouscatnetwork.com/public_html/>
       Require all granted
    </Directory>

    Remember if you have details needed for WordPress those instructions need to remain. I didn’t have a Directory area listed on my non-Wordpress sites.

  2. The files now need a .conf extension so move the rename/move the files to the new name
    sudo mv curiouscatnetwork.com curiouscatnetwork.com.conf
  3. Enable the new configuration
    sudo a2ensite curiouscatnetwork.com.conf
  4. Reload apache to reload the new configuration
    sudo service apache2 reload

More details from Linode.

The upgrade to Ubuntu 14.04 LTS was interrupted (I quit a window using the wrong command – oops). Luckily it wasn’t a big deal. I was able to delete the lock file.

sudo rm /var/lib/dpkg/lock

Then trying to update again

sudo apt-get dist-upgrade

gave a message telling me what command to use to have the upgrade continue.

sudo dpkg --configure -a

which seemed to work fine.

Related: Bash Profile Adjustments, Scrolling HistoryChecklist: Setting Up a New Domain on VPSModSecurity: Adjustments for WordPress

Reset Root Password on MySQL Database

How to reset the root password on a MySQL database.

Stop mysql using this command:

sudo /etc/init.d/mysql stop

Because you are not checking user privledges at this point, it’s safest to disable networking. Then, start the mysqld demon process using the –skip-grant-tables option using

sudo /usr/sbin/mysqld --skip-grant-tables --skip-networking &

Next, start the mysql client process using this command:

mysql -u root

from the mysql prompt execute this command to be able to change any password

FLUSH PRIVILEGES;

Then reset/update your password

SET PASSWORD FOR root@'localhost' = PASSWORD('password');

Related: Turn It Off and On Again (WordPress Loses Database Connection)Some MySQL cli syntax examplesKeeping Your Hosted Ubuntu Web Server Software Up to Date

Turn It Off and On Again

I had a WordPress blog lose the database connection. As I tried to troubleshoot it I rapidly got to the point of thinking that maybe just rebooting the server would fix things – since no changes had been made that should cause the database connection to be lost. But also I figured I couldn’t be so lucky that such a simple thing would work.

I tried to log into the database using the cli and it was failing. MySQL was still running – according to top. I have automated security updates setup for the VPS server running Ubuntu. My thought now is those updates somehow messed things up to the extent the server database connections somehow wasn’t working. I sure hoped that was the case.

I rebooted and hoped.

After a bit I was able to see that it was working.

When I went to reboot I noticed I hadn’t rebooted in a long time. My guess is I might have the automated security updates setup wrong on this server (maybe it is installing more than just the security updates), I’ll check. I have not had this problem before with other servers, obviously breaking a database in this way would cause lots of problems on production machines so I tend to think it is more likely I messed something up than this is a likely outcome when using automated security updates (but such things are possible which is why I think places with full time system admins and important servers rely on manual updates with professionals watching everything to be sure nothing obvious breaks).

My feeling is the longer you go with not rebooting the server the more likely some issues are to crop up (but also every reboot is more like to result in some broken thing, right then, than doing nothing so it is a tradeoff). And I could be wrong in that feeling, it is just what I guess without much evidence to support my guess.

Anyway I was very happy turning it off and on again worked. Honestly I went ahead and updated the server before I rebooted, but my guess is just turning it off and on again would have worked.

Related: Making Sure You Don’t Run Out of Space on Your VPSBasic MySQL Performance MonitoringWordPress error: Image could not be processed. Please go back and try again.

Top with Better Display Options

Scout Realtime is a Ruby Gem that allows you to view top in the browser. One huge advantage is to view charts of activity over time.

Scout Realtime is open source and free.

Related: System Monitoring Tools for VPSBasic MySQL Performance MonitoringKeeping Your Hosted Ubuntu Web Server Software Up to Date

Making Sure You Don’t Run Out of Space on Your VPS

Over the years I have had web sites I work on go down because the server ran out of space (when I wasn’t responsible for the system administration). Well today I had it happen for some sites on one of my servers.

I have a remote monitoring service so I was notified when the sites were unavailable. Looking in the error logs I could see I ran out of space, which is a fairly lame error to make, I think. I cleared up some space quickly and things were in working order again.

A few tips from this experience. To see data on space used and available space from the command line (linux/ubuntu) use the df command.

df

You could check that occasionally to see if anything strange is going on. But it is better to use something like Nagios to monitor the server and provide notice if usage goes past certain points is wise (75%, 80%…).

I found a nice way to find large files (that may be possible to delete to free up space)

sudo find . -mount -ls | awk '{print $7, $11}' | sort -rn > large_file_list

If you get an error with the file creation, you can log in as root (su) or create the file first and then it can overwrite the existing file.

It is smart to have log rotate setup for logs. I didn’t have it setup for every log. To create a file to keep track of all your logs for domains you can do the following. Create a file in the logrotate directory so it is run per your settings.

sudo vim /etc/logrotate.d/virtualhosts

This article from Slicehost provide details on options, a simple setup is to include text such as this in the file created in the line above.

/var/www/domain1.com/logs/*log /var/www/domain2.com/logs/*log {
  rotate 14
  daily
  compress
  delaycompress
  sharedscripts
  postrotate
    /usr/sbin/apache2ctl graceful > /dev/null
  endscript
}

Related: System Monitoring Tools for Ubuntu VPSPhusion Passenger Tips and Troubleshooting IdeasChecklist: Moving WordPress site to a New Host

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