Friday, December 19, 2014

Wordpress and LAMP in an LXC Container


I need to test some html running in Wordpress.
But I don't use Wordpress...obviously.

In Linux, that's easy to fix. Just install Wordpress.
Oops, not so easy: Wordpress pulls in an entire LAMP stack with it.
That's a lot to pollute my laptop with just to do some testing.

Containers to the rescue!
Let's spin up a container, install LAMP and Wordpress inside it, run the tests, then destroy the container.


The Router

I'm going to open a whole new port on my router's firewall for this, so others can help me test.

On the router, I want to forward port 112233 to the similar port on the server.

On the server, I want to forward port 112233 to the container's port 80. (That part is later)

Creating the container

Thanks the the amazing Stephane Graber for his detailed instructional series on how to create and use a container This is a slightly different setup than he did. Instead of installing directly on, say, a laptop, I'm installing the container onto a server that I access via ssh.

Three moving pieces: Laptop (me), Server (headless), Container (added to server)

So, from Laptop, I ssh into Server normally.

sudo apt-get install lxc               # Install the container system
sudo lxc-create -t ubuntu-cloud -n c1  # Download and install a 195MB cloud image of Ubuntu 14.10
sudo lxc-start -n wp1 -d               # Boot the image in the background (name is 'wp1')
sudo lxc-info -n wp1                   # Discover the IP of the image
    Name:           c1
    State:          RUNNING
    IP:            # <-- Ooh, there is the IP
ping                        # Check network connectivity on the container
    PING ( 56(84) bytes of data.
    64 bytes from icmp_seq=1 ttl=64 time=0.081 ms
    64 bytes from icmp_seq=2 ttl=64 time=0.085 ms

# Forward port 112233 to the container
sudo iptables -t nat -A PREROUTING -p tcp -i eth0 --dport 112233 -j DNAT --to-destination
sudo iptables -A FORWARD -p tcp -d --dport 80 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT

Set up LAMP and Wordpress within the container

The container is installed, started, and responds to ping.

sudo lxc-console -n wp1    # Login to the console of wp1 (username: ubuntu, password: ubuntu)

A couple words about the container.
I'm going to skip the part where you would delete the 'ubuntu' user and add your own admin user and password. But you should do it.
Also, two pieces of information you should have handy before going farther.
  1. Server's IP address on the LAN (mine is
  2. The real, fully qualified domain name ( that readers on the internet will use
The FQDN will be used to generate the MySQL account for the blog, and the create the wordpress config file. The LAN address will be used to link to the same accounts.

Special thanks to the Ubuntu community for putting together this fantastic tutorial about how to install wordpress in Ubuntu.

sudo apt-get install mysql-server wordpress   # 49 packages, 28MB download

Let's jump over to Laptop for a moment and check that Server's port forwarding and Container's apache service are working: Open a browser window, and look for You should get the apache default page. Success! Okay, now back to Container:

sudo ln -s /usr/share/wordpress /var/www/html/wordpress   # Make Wordpress accessible from apache

# Create mysql account, and link it to Wordpress
sudo gzip -d /usr/share/doc/wordpress/examples/setup-mysql.gz
sudo bash /usr/share/doc/wordpress/examples/setup-mysql -n freds_blog_fred_com  

# Prevent a Wordpress error (can't locate config file) from within the LAN
# by linking the LAN addr to existing FQDN config file
sudo ln /etc/wordpress/ /etc/wordpress/config-

<ctrl+a, q> to exit the console

Use Wordpress

The setup is complete. Since I'm on my LAN, I point my Laptop browser to and I get the Wordpress setup screen.

Outside, on the big wide internet, I would point it to (er, that's an example - you already know that's not my real blog).

Wordpress is ready for my data.

          Bye, Container!

Destroying the container

This is one of the true joys of LXC

sudo lxc-stop -n wp1
sudo lxc-destroy -n wp1

And all the work is wiped out forever....

Remember to clean up:
  • Uninstall lxc from the server
  • Delete the iptables rules on the server
  • Close the port on the router firewall

Saturday, December 13, 2014

Say, what are you doing this afternoon?

Bus Stop - Under The Rain by Leonid Afremov
Here's a happy little afternoon project for new users trying to play with a new
language or script, and getting their feet in the open-source ecosystem.

Your phone's handy weather app depends upon the goodwill of a for-profit data provider, and their often-opaque API (14 degrees? Where was it observed? When?) That's a shame because most data collection is paid for by you, the taxpayer.

Let's take the profit-from-data out of that system. Several projects have tried to do this before (including libgweather), but each tried to do too much and replicate the one-data-provider-to-rule-them-all model. And most ran aground on that complexity.

Here's where you come in

One afternoon, look up your weather service's online data sources. And knock together a script to publish them in a uniform format.

Here's the one I did for the United States:
Worldwide METAR observation sites
US DOD and NOAA weather radars
US Forecast/Alert zones

  • Looking for data on non-METAR (non-airport) observation stations, weather radar sites, and whatever forecast and alert areas your country uses.

  • Use the same format I did: Lat (deg.decimal), Lon (deg.decimal), Location Code, Long Name. Use the original source's data, even if it's wrong. Area and zones should use the lat/lon of the centroid.

  • The format is simple CSV, easy to parse and publish.

  • Publish on GitHub, for easy version control, permalinking, free storage, and uptime.

  • Here's the key: Your data must be automatically-updated. Regularly, your program must check the original source and update your published version. How I did it with a cron job. Publish both the data and your method on GitHub. 

  • When you have published, drop me an e-mail so I can link to your data and source.

If you do it right, one afternoon to setup your country's self-updating database. Not a bad little project, you learn a little, and you help make the world a better place.

My country doesn't have online weather data

Sorry to hear that. You're missing some great stuff.

If you live in a country with a reasonably free press and reasonably fair elections, make a stink about it. You are probably already paying for it through taxes, why can't you have it?

If you live somewhere else, then next time you have a revolution or coup, add 'open data' to the long list of needed reforms.

What will this accomplish?

This will create a free, sustainably updated, uniform, crowdsourced set of accurate worldwide data that will be easy to compile into a single global database. If you drop out, your online code will ensure another volunteer can step in.

This is one fundamental tool that other free-weather projects have lacked. And any weather project can use this.

The global database of locations is really small by most database standards. Small enough to easily fit on a phone. Small enough to be bundled with apps that can request data directly from original sources...once they can look up the correct source to use.

How will this change the world?

It's about simple tools that make
it easy to create free, cool software.
And it's about ensuring free access to data you already paid for.

Not bad for one afternoon's contribution.

Friday, December 12, 2014

How to set up automatic Github uploads

Back to basics

For years, I have been playing with US Weather Data.

A couple years ago, I came up with a lookup server for US weather locations, and -of course- had all kinds of plans for how to expand it to more services and more countries.

So, of course, it went nowhere.

This week, I took a look at the issue again, and came up with a simple set of lookup tables (yes, a tiny database) to replace the server. It reduced the amount of code by about 70%, and it's finally in a maintainable, expandable form. It's simple, and ready for a few drive-by patches.

Which leads to the next to share it with the world?

Well, in this decade, sharing software and data means putting it on GitHub.

Creating the GitHub repositories

We have a Python 3 script that creates the database, another Python 3 example script that consumes the database, and the three CSV files that make up the database tables. Most consumers will probably just want the data for their own purposes - they really don't need the scripts (and it would be quite rude for millions of users to hit NOAA servers to produce their own databases each week)

So I created two repositories on GitHub, one for the data and another for the optional scripts.

If you haven't used GitHub, you first go online and create your account and create the repositories (with initial README file) in a web browser. Then:

cd /tmp
git clone   # Create a clone of the online repository
cd data
cp /home/somewhere/else/data/* ./               # Add existing data files into the local clone
git add ./*                                     # Tell git to track the new data files
git commit -m "Add initial data"
git push origin master                          # Push the changes back to GitHub
  Username for '':
  Password for '': 
cd /tmp 
rm -rf /tmp/data                                # Clean up

Overall, it's pretty simple. For the next iteration:
  • We must automate the upload credentials so it doesn't prompt for a username and password each time.
  • We must add a cron job that creates the data for upload.
  • Let's move this project from /tmp on my laptop to the server where it will live permanently. This also means that the server should pull the latest Python script...which is also hosted on GitHub.

Let's setup the server:

sudo apt-get install git    # On this server, about 3 MB of download
sudo apt-get install python3-httplib2  # Script dependency
mkdir uploads
cd uploads
git clone          # Setup the local 'data' repository
git clone       # Setup the local 'software' repository
weather/                        # Use the script to update CSVs in ~/uploads/data
cd data
git config --global ""  # First time setup
git config --global "My Name"                # First time setup
git config credential.helper store                     # First time using this repo setup
git add -A
git commit -m "Test update"
git push origin master
  Username for '': my-github-login-name   # First time using this repo setup
  Password for '':   # First time using this repo setup

Automating the process

So now subsequently, without all the first time setup:


now=$(/bin/date +%F)

cd $dir/weather
/usr/bin/git pull "$hub"/weather      # Update the database_creator script

cd $dir/data
/usr/bin/git pull "$hub"/data         # Need to pull to be able to push later

$dir/weather/  # Do the update
/usr/bin/git add -A                   # Record any changes
/usr/bin/git commit -m "Scheduled update $now"
/usr/bin/git push origin master
exit 0

And now we can run the shell script weekly from a user cron job:

5 6 * * 7 /home/ian/uploads/cron/weekly_weather > /home/ian/uploads/weather.log 2>&1

A couple of tests, and it works.

It's completely automatic.

Once a week, my server downloads the latest make-a-database script, builds the database, and uploads the database to GitHub for the world to use.

The data

If you want to see the final product (the lat/lon lookup tables for US weather), you can get them at:

They will, of course, be automatically updated weekly.