Dependencies

• Apache 2.2.x
• Imagemagick 6.6+
• libcurl 7.18.0+

Installation

Add the following to the Apache configuration:

<IfModule !mod_dims.c>
    LoadModule dims_module modules/mod_dims.so
</IfModule>

AddHandler dims-local .gif .jpg

<Location /dims/>
    SetHandler dims
</Location>

<Location /dims3/>
    SetHandler dims3
</Location>

<Location /dims-status/>
    SetHandler dims-status
</Location>

This assumes mod_dims.so has been installed in $HTTP_ROOT/modules.

Errors

There are three classes of errors in mod_dims;

• Errors caused during downloading of a source image. These come directly from libcurl and are logged as-is.

• Errors caused during an ImageMagick operation. These come directly from ImageMagik and are logged as-is.

• Errors caused during processing of a request by mod_dims. These fall into the category of bad input checking, bad config, etc.

ImageMagick Timeout Error Format:

[client Imagemagick operation, '', timed out after 4 ms

would be something like "Resize/Image" or "Save/Image".

General Error Format:

Errors will be in the following format in Apache's error log:

[client ] error, '', on request:

For example:

[client 10.181.182.244] Imagemagick error, 'no decode delegate for this image format `'', on request: /20080803WI55426251_WI.jpg/TEST/thumbnail/78x100/

Common libcurl Error Messages:

These message are usually self explanatory so no explain is provided. The URL that failed will be logged along with this message.

• Couldn't connect to server
• Couldn't resolve DNS
• Timeout was reached

Common mod_dims Error Messages:

• Requested URL has hostname that is not in the whitelist. (aaolcdn.com)
• Application ID is not valid
• Parsing thumbnail geometry failed
• Parsing crop geometry failed
• Failed to read image This occurs if ImageMagick had trouble reading the image.
• Unable to stat image file This occurs when a local request is unable to find the image to resize.

Common ImageMagick Error Messages:

• Memory allocation failed This should rarely occur, if ever, but usually when it does it's the result of an ImageMagick timeout.

• unrecognized image format

• no decode delegate for this image format

This happens when ImageMagick doesn't no how to read a source image.

• zero-length blob not permitted

This may occur if there was a failure to download the source image.

• Unsupported marker type 0x03 This may occur if the image is corrupted. The "0x03" may be different depending on the corruption.

Other more serious errors:

Any errors that have "Assertion failed" are results of bugs in the code and can be considered serious.

• Assertion failed: (wand->signature == WandSignature), function MagickGetImageFormat, file wand/magick-image.c, line 4137.