URL-based image processing for Django
django-url-imaging provides URL-based image processing functionality for Django projects. It features a plugabble storage system with implementations for storing images locally, on Amazon S3 or using the SCP utiltiy to copy them to another server.
Once installed and configured, django-url-imaging will allow you to embed thumbnails and other image transformations using nothing more than a specially crafted URL. As an example, if you configured django-url-imaging to listen for requests on /thumbnails/ and needed to have a resized copy of the image at http://media.mydomain.com/foo.jpg, you would just create a link like:
<img src="/thumbnails/resize/50x50/media.mydomain.com/foo.jpg" />
django-url-imaging provides many different URL-based commands for image processing such as cropping, resizing, scaling, watermarking and much more. For more information on django-url-imaging, please check out the Wiki.
$ sudo python setup.py install
- Add the urlimaging app to INSTALLED_APPS
- Include urlimaging.urls as a resource in your urls.py:
- Finally, depending on if you want to use S3 or local file storage, configure the appropriate settings:
Depending on how you plan to store your images, you will need to add one of the following sets of properties to your settings.py file:
- IMAGE_STORAGE_BACKEND – This should be set to ‘S3ImageStorage’ to specify the S3 storage backend.
- S3_BUCKET_NAME – The name of the bucket (which should already be created) on S3 where images will be stored.
- AWS_ACCESS_KEY_ID – The AWS access key provided by Amazon.
- AWS_SECRET_ACCESS_KEY – The AWS secret access key provided by Amazon.
- S3_EXPIRES (optional) – The length of time which the S3-generated URL will be valid.
Local Image Storage
IMAGE_STORAGE_BACKEND – This parameter should be set to ‘LocalImageStorage’ for the local image storage backend.
IMAGE_WHITELIST_FN – A function which takes a url as an argument and uses that to decide whether or not to allow it to be processed. By default it is defined as lambda url: True which will allow for processing all images. To restrict it to only process images in your MEDIA_URL, set it to:
IMAGE_WHITELIST_FN = lambda url: settings.MEDIA_URL in url
IMAGE_STORAGE_DIR (optional) – The full path to the directory where images should be stored if this is not set, the value is inherited from MEDIA_ROOT. This directory should be publicly accessible since the application doesn’t serve images directly from it.
IMAGE_PATH_PREFIX (optional) - A path that is prepended to the path of the processed image.
If you’d like to use the scp command to copy the generated files to another UNIX-like server, configure the following options:
- PROCESSED_MEDIA_URL - A URL where the images can be accessed once they are stored
- SSH_MEDIA_USER - The username which has ssh access on the remote host
- SSH_MEDIA_PATH - The path to where the images will be stored on the remote host
- SSH_IDENTITY_FILE - If an identity file is required for access to the remote host, this is the path to that file.
Custom django-admin commands
django-url-imaging adds the following custom command to the project’s django-admin:
- removeoldimages - Will remove any processed images which haven’t been visited for a a predetermined time (defaults to a week). It is recommended that this is added to a scheduling system such as cron to be run every couple of days.
- MEDIA_URL – If you’re using the LocalImageStorage backend, setting this parameter gives the root url that serves images stored in the IMAGE_STORAGE_DIR
- FONT_PATH - The path to the font file to be used when using the watermark operation. Defaults to /usr/share/fonts/truetype/freefont/FreeSansBold.ttf
- IMAGE_EXPIRATION_DAYS - The number of days before images which haven’t been visited are deleted. Defaults to 7.