Lonnon Foster

Fixing git pre-commit hook woes

Fri, 24 Apr 2009 02:52:45 GMT

I’ve had something strange occur when attempting to commit changes to a Git repository located on a flash drive. A pre-commit hook, which is a script Git runs before the git commit command does its thing, prevents me from committing files until I’ve removed whitespace characters from the ends of all the lines in the files. Cleaning out such whitespace is good practice if you’re working on a project and you submit your changes as patches; the patch mechanism has a tendency to barf on lines that contain trailing whitespace.

My problem is that not only am I not working on a project where I submit patches, some of the Rails generators create files that contain trailing whitespace (I’m looking at you, RSpec). When I found that the rake db:migrate task adds trailing whitespace to the schema.rb file, I nearly went ballistic. I’d be okay with keeping the whitespace out of my own code, because I’m just OCD enough to enjoy the exercise, but having to fix code generated by automation tools just pisses me off.

To add to the aggravation, the pre-commit hook didn’t seem to run when I was committing to Git repositories on the hard drive of my Mac. I ran afoul of the hook only when committing to a repository on the flash drive or on my Windows laptop.

I got fed up with it enough today to do a bit of digging into the guts of Git. The pre-commit script is created when git init sets up a new repository, and the script is located in a project’s working directory under .git/hooks. The pre-commit script’s comments indicate that it’s designed to prevent trailing whitespace from getting into files destined for patches. The comments also mention the following:

To enable this hook, make this file executable.

Aha! Now we’re getting somewhere. I checked the file permissions, and sure enough, the file is executable in a repository created on the flash drive. However, it isn’t executable in a repository created on the Mac’s hard drive. Digging a bit deeper, I found that the original copy of pre-commit comes from /usr/local/share/git-core/templates/hooks, where the file is also not executable.

It looks like git init loses the file permissions when it copies everything from the Git templates directory over to the flash drive, thereby resulting in files that have full permissions enabled. This makes sense, given that the flash drive is FAT32-formatted; the filesystem doesn’t support Unix-style execution permissions. My Windows laptop has the same problem.

Finally knowing what causes the problem, I defused it by renaming pre-commit in the templates directory to pre-commit.patching. Now if it’s copied with full permissions, it won’t matter, because Git’s looking for a file named pre-commit. I may at some point need to re-enable the hook if I start submitting patches to someone else’s project, but in the meantime, for the majority of work that I do in my own one-man repositories, I’m no longer bothered by an over-protective pre-commit hook.

Originally published at nyerm. You can comment here or there.

Deploying a Sinatra app on Dreamhost

Tue, 24 Mar 2009 02:05:09 GMT

I’ve been down with the flu and confined to the couch for the last couple of days, so what better way to pass the time than learning a new web framework and deploying it to Dreamhost? Only a brain cooked by fever would think something like this might qualify as fun, but my grey matter is pretty close to hard-boiled by now, and I can only play so much WoW before wanting to shoot myself. So I fired up Google and a text editor and started hacking away.

Enter Sinatra

The most pleasant part of this whole experience was picking up Sinatra, a minimal Ruby web framework that hearkens back to the simpler days of shoving a bunch of Perl into a CGI script and calling it a day. Like the CGI script of yore, you can easily stuff a small app into a single file. Unlike that CGI script, Sinatra lends itself well to MVC separation, test- or spec-driven development, and other modern programming conveniences. It’s ideal for slapping a quick user interface on some Ruby code.

Sinatra’s readme is a great drink-from-the-fire-hose introduction to what the framework can do, but the minimal “hello world” application on Sinatra’s home page is a bit too minimal to be instructive. There are some great tutorials listed on the Sinatra site, though. In particular, I found Building an iPhone web app in under 50 lines with Sinatra and iUI to be just the ticket for quickly getting up to speed on what Sinatra does. As an added bonus, it’s got iPhone stuff in it, which is worth at least two squares in Buzzword Bingo.

Dreamhost, prepare to be boarded

The first step is to make a domain in the Dreamhost panel and configure it to run Passenger. From what I’ve been reading, Passenger isn’t really set up to run apps in a subdirectory (like example.com/myapp), so a new subdomain is the way to go here (like myapp.example.com). Dreamhost lets you define as many subdomains as you want, so this isn’t a problem; just click Add New Domain / Sub-Domain in the Domains > Manage Domains screen.

On the Fully Hosted page that appears, check the Ruby on Rails Passenger box. Then set up the web directory as you would for any other site, but add current/public to the end of the path. We’re using Capistrano to deploy the app, and Capistrano wants to deploy to a directory called current. Passenger expects the web directory to point to the app’s public folder. Combining those two makes a path ending in current/public.

Let Dreamhost do its thing and create the new domain. Depending on how flaky its systems are and the current phase of the moon, you may have a working subdomain in a few minutes or several hours. I failed my saving throw versus Broken Scripts and got the several hours version when I set up the domain yesterday, resulting in the dreaded bad_httpd_conf error. You can sometimes force Dreamhost to rebuild your messed up httpd configuration by going back to the Fully Hosted page and just clicking the Fully host this domain now button. No need to change any settings on the page; apparently, performing this little ritual will kick the scripts into gear, and with luck, you’ll have a working subdomain with Passenger running on it.

When Dreamhost’s scripts get around to creating the domain, they’ll also create its web directory. You’ll need to ssh over to your account and delete the current directory that’s there. Capistrano recreates current as a symbolic link pointing to the currently deployed version of the application.

  > cd ~/sites/sinatra-test.nyerm.com
  > rm -rf current

Vendoring Sinatra and Rack

Though it’s possible to get your own local gem repository working on Dreamhost (and for some gems, like RMagick, necessary), I find it simpler to unpack gems required by the app into a vendor folder and just deploy them with the rest of the application.

As I write this, Dreamhost doesn’t have Sinatra installed at all, and its copy of Rack is version 0.4.0, which is incompatible with the latest Sinatra (0.9.1.1). So, I unpacked both of these gems into a vendor folder. Run these commands from the root of your Sinatra project:

  > mkdir vendor
  > cd vendor
  > gem unpack rack
  > gem mv rack* rack
  > gem unpack sinatra
  > gem mv sinatra* sinatra

Be sure to change the require 'sinatra' line at the start of your application so it requires the vendor copy of Sinatra:

  require 'vendor/sinatra/lib/sinatra'

Capifying and racking

With Dreamhost ready to receive your application, it’s time to get Capistrano in on the action. First you’ll need to create a Capfile so Capistrano knows where your application’s source is and where it should be deployed.

  > capify .

Open Capfile in your favorite editor and replace the sparse default contents of the file with something more like this:

  load 'deploy' if respond_to?(:namespace)

  default_run_options[:pty] = true
  
  # be sure to change these
  set :user, 'username'
  set :domain, 'domain.com'
  set :application, 'myapp'
  
  # the rest should be good
  set :repository,
      "#{user}@#{domain}:git/#{application}.git"
  set :deploy_to,
      "/home/#{user}/#{application}.#{domain}"
  set :deploy_via, :remote_cache
  set :scm, 'git'
  set :branch, 'master'
  set :git_shallow_clone, 1
  set :scm_verbose, true
  set :use_sudo, false
  
  server domain, :app, :web
  
  namespace :deploy do
    task :restart do
      run "touch #{current_path}/tmp/restart.txt" 
    end
  end

I found a number of sites with reasonable instructions for deploying Sinatra to Dreamhost, and my favorite is John Nunemaker’s guide on RailsTips. The Capfile above is from his article, which is well worth a look.

The bits that you might need to change in the Capfile here, aside from the obvious :user, :domain, and :application fill-ins, are the :repository and :deploy_to paths. For example, I keep my personal Git repository in a directory that’s served out by Apache so I can browse the contents. Also, my file structure has an extra sites directory above the web roots, because I don’t like the mess that Dreamhost’s default paths make of my home directory. The appropriate portion of my Capfile looks like this:

  set :repository,
    "#{user}@#{domain}:sites/git.nyerm.com/#{application}.git"
  set :deploy_to,
    "/home/#{user}/sites/#{application}.#{domain}"

The last ingredient needed for deployment to Dreamhost is a rackup configuration file, config.ru. Pop open the text editor again and enter the following:

  require 'vendor/rack/lib/rack'
  require 'vendor/sinatra/lib/sinatra'
  
  set :run, false
  set :environment, :production
  set :views, "views"
  
  require 'hi.rb'
  run Sinatra::Application

Deploying to Dreamhost

Check all your files in and push to the remote Git repository, and you should be ready to deploy with the following commands:

  > cap deploy:setup
  > cap deploy

Assuming you don’t have any typos and Dreamhost is choosing to be merciful, you should now have a Sinatra app running on Dreamhost. On the other hand, if like me you’re not a divine being of pure logic, you might want to enable Rack’s logging middleware so you have some clue what’s not working. Stick the following in your config.ru, and you’ll get something more useful than you’ll find in the Apache logs:

  log = File.new("log/sinatra.log", "w")
  STDOUT.reopen(log)
  STDERR.reopen(log)

Credit where credit is due

I found the following articles helpful when trying to get all this working:

Originally published at nyerm. You can comment here or there.

Helipad, now on GitHub

Tue, 10 Mar 2009 01:17:53 GMT

The Helipad Ruby interface is now available on GitHub in addition to its original home on RubyForge.

There’s no difference at all between the two, apart from the GitHub copy bearing my name, which is GitHub’s convention for preventing collision between identically-named gems. If you wish to install the gem from GitHub instead of RubyForge, you can do the following:

  > gem sources -a http://gems.github.com
  > sudo gem install lonnon-Helipad

Originally published at nyerm. You can comment here or there.

Improved dynamic human-readable RESTful routing

Fri, 20 Feb 2009 10:11:56 GMT

Earlier in the week I posted about making dynamic RESTful routes in Rails. At the end of the article, I mentioned that the method I was using might not work in a production environment, and after searching Agile Web Development with Rails for the word “restart,” I confirmed my suspicions. Generating routes on the fly from data runs afoul of caching, requiring the server to be restarted to pick up changes to the routing. That rules it out as a reliable way to generate pretty URLs.

To recap, I’ve already used map.resources to generate the usual http://example.com/sections/1 style of REST URL. I want to be able to route a URL like http://example.com/about to the show method of my Sections controller, as well, to improve human readability (and SEO) of the URL.

Fortunately, I’d already thought about how to do this. The solution is to capture the highly variable URL in a route and process it in the Sections controller to figure out where to send it. The following is now the very last route in my routes.rb file:

  map.section_dispatch ':section',
                       :controller => 'sections',
                       :action => 'show'

This route’s location at the very end of routes.rb is no accident. It’s extremely promiscuous, and it will latch onto any URL of the form http://example.com/foo. If it came earlier in the routing, it would prevent many other routes from being triggered, including the http://example.com/sections REST route that calls the index action to display a list of all the sections.

The route captures whatever comes after the domain part of the URL in the :section parameter and sends it along to the show action in the Sections controller, which is where the really interesting stuff happens:

  def show
    section = params[:section]
    if section.nil?
      section = 'home'
    end
    @section = Section.find_by_name(section)
    unless @section
      render :file => "/404.html",
             :status => :not_found
    end
  end

Remember I said the route is promiscuous? Here’s real proof: even a nil :section parameter gets picked up by the route, which means the root URL for the site (http://example.com) is sent to the show action. The check for section.nil? assigns the Home section as the desired target; Home is where I keep any bits of content that appear on the front page of the site.

The show action then looks for a Section in the database whose name matches whatever the route picked up from the URL, assigning the Section it finds to the instance variable @section for use by the Section view. However, if the name in the URL doesn’t match any Section names, a render call sends the browser a 404 Not Found error and renders an appropriate page so the site visitor knows she’s typed in a bad URL. Eventually, I’ll replace the static 404.html file with a new controller and view that can generate a more useful 404 page with a search box and helpful links, but that’s a project for another day.

Originally published at nyerm. You can comment here or there.

Crashing InDesign with bookmarks and hyperlinks

Thu, 19 Feb 2009 01:55:57 GMT

After generating a table of contents for a multi-document InDesign book, I tried to export the book to PDF. Adobe InDesign CS3 fell right over, presenting me with the friendly “please tell our developers what the hell you were doing that crashed our fine software” dialog.

When generating the table of contents (Layout > Table of Contents), I selected the Create PDF Bookmarks option. If I omitted the bookmarks, InDesign was able to export a PDF without any trouble, but of course, the PDF was missing the bookmarks. Because the book is nearing 100 pages, having functional bookmarks in the sidebar of Adobe Reader, as well as working hyperlinks in the table of contents, is a necessity for navigating this beast.

After trying every combination I could think of in the Table of Contents dialog, I turned to the Export Adobe PDF dialog (Book panel menu > Export Book to PDF) and started flipping switches there. I discovered that the Bookmarks option in the Include section of the dialog didn’t make any difference; whether on or off, InDesign still crashed when producing a PDF.

I turned off the Hyperlinks checkbox, and lo and behold, InDesign continued chugging away and gave me a PDF. None of the bookmark sidebar links worked, nor any table of contents links, nor any other hyperlinks anywhere in the book, but at least InDesign decided to stay with me this time instead of unceremoniously quitting.

On the theory that a logical approach wasn’t working, I started poking at random settings. I got lucky with the first one I tried; turning off Create Tagged PDF not only prevented InDesign from crashing, it produced a fully functional PDF with working bookmarks and hyperlinks. Mission accomplished!

I’m a bit frustrated that InDesign refuses to make a tagged PDF with working hyperlinks. The whole point to tagged PDFs is that they define document structure, which makes them accessible to assistive reading technologies and lets mobile devices reflow the content to better fit tiny screens. This book isn’t likely to reach a huge audience to begin with, but it hurts to think that InDesign might be shrinking that audience even further. Given a bit of googling, it appears I’m not the only one to find problems with tagging in InDesign CS3.

Originally published at nyerm. You can comment here or there.

TextMate as a blogging tool

Wed, 11 Feb 2009 22:49:57 GMT

There’s something extraordinarily wrong about this. I just discovered, through Barry Hess’ blog, that TextMate has a blogging bundle. It hooks up to the ubiquitous XML-RPC interfaces sported by modern blogging software (Wordpress, Movable Type, Typo, what-have-you) and lets you use your text editor to create and edit weblog posts.

This is a far more comfortable interface for composing blog articles than any I’ve encountered, including the feature-rich web interface in Wordpress itself. I don’t use the embedded WYSIWIG editor widget in Wordpress, preferring to format my posts with Textile so I can just keep typing instead of trying to figure out what all the little buttons are supposed to do. TextMate does a great job with highlighting Textile, providing just enough coloring and styling to let you know that you’re doing the markup right without getting in the way of the writing.

On top of that, I’ve got the security of knowing that my prose isn’t going to disappear if the browser crashes or my network connection flakes out. Need more time to compose a lengthy article? Just save it locally, as a simple text file, and come back to it later. This is the very definition of “no muss, no fuss.”

Now to see if this bundle works as well in TextMate’s Windows cousin, e, so I can get the same great feature on my laptop that I have on the iMac at work.

UPDATE (2009-02-11 21:03): Yes, indeed, this same power exists in e. I am one happy camper.

Originally published at nyerm. You can comment here or there.

Silly meme time

Tue, 25 Nov 2008 02:19:13 GMT

Grab the book nearest you. Right now.
Turn to page 56.
Find the fifth sentence.
Post that sentence along with these instructions on your LJ.

Don’t dig for your favorite book, the coolest, the most intellectual. Use the closest.

Armadillos: This witty description of the armadillo was produced by the descit environment.

Alas, the nearest book to me is Leslie Lamport’s L^AT_EX User’s Guide and Reference Manual.

Originally published at nyerm. You can comment here or there.

Apache hinkyness

Wed, 29 Oct 2008 00:57:00 GMT

I encountered a weird web problem today when adding images to the company website. The new images I’d added wouldn’t appear on their page, and when pointing the browser directly at them, I received a 403 Forbidden error.

After insuring that the permissions and filenames were all correct, I sat down with the sysadmin to see if a second pair of eyes and a root login could find anything amiss. After spending half an hour of finding nothing in the logfile or permissions settings, we both gave up.

I returned to my desk, and on a whim, performed the following commands:

cp image-file.gif foo.gif
rm image-file.gif
mv foo.gif image-file.gif

I can’t imagine why this would have solved the problem, but it did. The implications — that something might be messed up deep within the innards of Apache or the Fedora filesystem — make me worry what other bizarre behavior I can expect from the webserver in the future.

This isn’t the first time machines have had odd behavior in my presence, which I’ve been able to dispel by performing seemingly unrelated actions. I’m obviously in the wrong business. I should pack my bags and hit the road as a traveling computer faith healer.

Originally published at nyerm. You can comment here or there.

Only one

Wed, 03 Sep 2008 02:15:45 GMT

One of the best bits about being me: I have a unique name.

HowManyOfMe.com

There are
1
or fewer people with my name in the U.S.A.

How many have your name?

Originally published at nyerm. You can comment here or there.

iPhone clone window bookmarklet

Sat, 30 Aug 2008 10:26:46 GMT

Mobile Safari’s multiple window interface is amazing, but it lacks the ability to explicitly open a link in a new window. Being a fan of tabbed browsing in desktop browsers, I find it irritating not to be able to leave the current window in place while I follow a link or two.

I don’t have a clever hack to force Safari to open a link in a new window, but I do have the next best thing: a javascript bookmarklet that opens the current page in a new window. This makes following a link in a new window possible, if a bit inelegant.

To install the bookmarklet:

Drag the Clone Window link below to your bookmark bar in desktop Safari. Or if you sync to Internet Explorer, right-click the link and choose Add to Favorites, then save it to the Links folder.

Clone Window

Now that you have the bookmarklet on your browser’s link bar, connect your iPhone to your computer and sync bookmarks through iTunes.

To use the bookmarklet:

In Mobile Safari, tap the bookmarks button (open book icon) at the bottom of the screen.

Locate the Clone Window bookmark; it’s in the Bookmarks Bar folder if you sync with Safari, or in the Links folder if you sync with IE.</ok>
Tap the Clone Window bookmark. Mobile Safari opens a copy of the current page in a new window. You may now follow any link on the page, secure in the knowledge that the page you started from will still be there in another window.

Happy browsing!

Originally published at nyerm. You can comment here or there.

Jott is a mind boggling…

Sun, 17 Aug 2008 19:24:35 GMT

Jott is a mind boggling cool technology. I’m currently posting to my blog by calling a phone number and having it transcribe everything and stick it into a blog post. The future is here and man it’s really damn cool. listen

Originally published at nyerm. You can comment here or there.

Running zsh on the iPhone

Sun, 10 Aug 2008 19:44:03 GMT

I jailbroke my iPhone 3G as soon as the iPhone Dev Team had posted their tool to do so, and ever since, I’ve been screwing about with the command line. There’s something deeply appealing to my inner nerd about having Unix on my phone, and recreational command line hacking is more fun for me than many of the games available for iPhone.

The one thing missing on my journey to mobile nerdvana was zsh, my favorite shell. Cydia had a zsh package available as soon as Pwnage Tool 2.0 came out, and I promptly installed it. Unfortuanately, though I was able to run zsh from the command line, I couldn’t figure out how to set it as the default login shell.

Well, a bit of googling later, and I found out that on the iPhone (and possibly Mac OS X, whence iPhone derives much of its unixy goodness) editing /etc/passwd won’t do the trick. In fact, there’s a big fat comment at the head of /etc/passwd that informs you that editing it won’t be particularly useful:

# Note that this file is not consulted for login. # It only exisits for compatability with 4.3BSD utilities.

How then to set up default shells? Edit /etc/master.passwd, of course. iPhone uses this file as its authoritative user database, and changes to the login shell in this file work quite well. Change /bin/sh to /bin/zsh at the ends of the root and mobile lines, and you’re good to go. Here’s /etc/master.passwd after I’ve modified it for zsh goodness:

## # User Database # # This file is the authoritative user database. ## nobody:*:-2:-2::0:0:Unprivileged User:/var/empty:/usr/bin/false root:rootpassword:0:0::0:0:System Administrator:/var/root:/bin/zsh mobile:password:501:501::0:0:Mobile User:/var/mobile:/bin/zsh daemon:*:1:1::0:0:System Services:/var/root:/usr/bin/false _securityd:*:64:64::0:0:securityd:/var/empty:/usr/bin/false _mdnsresponder:*:65:65::0:0:mDNSResponder:/var/empty:/usr/bin/false _sshd:*:75:75::0:0:sshd Privilege separation:/var/empty:/usr/bin/false _unknown:*:99:99::0:0:Unknown User:/var/empty:/usr/bin/false

Note that you must be logged on as root to edit /etc/master.passwd.

Originally published at nyerm. You can comment here or there.

Finally moblogging

Wed, 23 Jul 2008 00:25:15 GMT

WordPress for iPhone is finally out, which gives me the opportunity to post random stuff from wherever I’m standing, assuming I’m standing within range of AT&T’s wireless system.

This is the kind of thing I’ve wanted for years, and though there have been ways to do this for some time now, they’ve all been too clunky, expensive, or both for me to stay interested in them too long.

I can even include pictures right from the phone, which might never get old:

Originally published at nyerm. You can comment here or there.

Sweet ride

Sat, 19 Jul 2008 04:44:29 GMT

It’s long been surmised by tuners and drift racing fanatics that stickers not only add to the aesthetic of your automobile, they can actually make your car go faster. If you extend this theory a bit further, you realize that lots of stickers will turn your Honda into a hypersonic missile of cool.

That’s the theory. In practice, it makes you look like a complete dufus. Case in point: Mr. G. Antonov, better known to his friends as “Jawls,” as it’s written on the driver’s side door. He’s obviously put this machine through its paces, though; this isn’t some prettied-up curb queen with a big stereo in it. Have a look at the Flickr set for all the stunning details.

I can respect that it’s a real Japanese Honda. This baby’s got right-hand drive. I only wish him the best of luck next time he visits a drive thru.

Originally published at nyerm. You can comment here or there.

Crossposting to LiveJournal

Sat, 19 Jul 2008 01:13:13 GMT

I’ve been slowly warming to LiveJournal, not because I love its interface or features, but because I have a number of friends over there I keep tabs on. I post infrequently enough to this blog, and coming up with more posts to put in a LJ seems far-fetched, at best.

To the rescue: the LiveJournal Crossposter, a WordPress plugin that automatically copies posts from my blog to my LJ as I make them. I was going to let it copy every post from here to LJ, but that went poorly; somewhere after the first hundred posts or so, the plugin tried to shove some malformed XML at LiveJournal, and its parser barfed with a delightful Perl error message.

As a result, I only managed to push posts from 2003, and not wanting a gap in there, I went through and deleted them all from LJ. By hand. This is why I’m using WordPress. I do stupid power-user stuff like this all too often.

With any luck, this should be my first post on LiveJournal. To those of you following my blank LJ already: hello, and I apologize if I just spammed your friends pages with a honking huge pile of old posts that are now deleted. With even more luck (and possibly a miracle or two), I’ll post things often enough to make it interesting for people.

Originally published at nyerm. You can comment here or there.