Matthew Bass

  • CORS woes on Heroku

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    After spending the past 4 hours attempting to solve what boiled down to a rather simple problem, I figure I’d better blog about it to save someone else the time and effort.

    If you’ve been leveraging Passenger’s new –nginx-config-template command line option to add CORS headers to static assets served from a Rails app hosted on Heroku, and the CORS headers recently disappeared under mysterious circumstances… read on.

    I’ve been using the method described here to add CORS headers to custom fonts served from a Heroku-hosted Rails app that’s proxied by Nginx which handles serving static files. I recently updated to Rails 4.2.2 and suddenly, my custom fonts (.woff and .woff2 files) no longer had CORS headers on them.

    After the aforementioned hours spent scratching my head, I discovered that the latest version of the sprockets gem is generating asset digests that are 64 chars in length, where previously they had been 32. Nginx’s default regexp for identifying requests for static assets assumes the digest will be 32 chars long, like so:

    # Rails asset pipeline support.
location ~ "^/assets/.+-[0-9a-f]{32}\..+" {
  error_page 490 = @static_asset;
  error_page 491 = @dynamic_request;
  recursive_error_pages on;</code>

  if (-f $request_filename) {
    return 490;
  }
  if (!-f $request_filename) {
    return 491;
  }
}

    Changing the regexp to recognize digests that are 64 chars in length immediately solved the problem:

    location ~ "^/assets/.+-[0-9a-f]{64}\..+" {
   ...
}

    I had to laugh after something so stupid and silly cost me a good chunk of my Saturday to debug. But at least it’s working now. My statically served custom fonts have the correct CORS headers and Chrome and Firefox are happy again.

Need help?

I’m an independent software developer available for consulting, contract work, or training. Contact me if you’re interested.

  • Quote of the Week: John Adams

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    “We have no government armed with power capable of contending with human passions unbridled by morality and religion. Avarice, ambition, revenge, or gallantry, would break the strongest cords of our Constitution as a whale goes through a net. Our Constitution was made only for a moral and religious people. It is wholly inadequate to the government of any other.” — John Adams

  • Textile toolbar plugin for Rails

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    Have you ever wanted a WYSIWYG-style toolbar that generates Textile markup? textile_toolbar is a Rails plugin that does just that. Extracted from a recent Terralien project, it’s a great way get your users used to the power and simplicity of Textile without frightening them away with long markup guides. Check out the announcement on the Terralien blog for more information.

    To install from the command line:

    script/plugin install git://github.com/pelargir/textile_toolbar.git

    Update: A live example of a Textile-enabled text area can now be found here.

  • Surrounding text with a tag using Ruby’s gsub

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    Here’s how to identify a keyword in a block of text using a case-insensitive regular expression, and surround that keyword with an HTML tag:

    text = "hello world, this is a test"
text.gsub!(/(WORLD)/i, "\1")

    The following string is produced:

    hello world, this is a test

    Note that \1 references the group in the regex (surrounded by parens). This results in the original value being placed within the HTML tags, instead of the uppercased WORLD in the regex.

  • Joint Economic Hearing from this morning

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