The clack-static-asset-middleware Reference Manual

This is the clack-static-asset-middleware Reference Manual, version 1.1, generated automatically by Declt version 4.0 beta 2 "William Riker" on Sun Jan 15 05:38:18 2023 GMT+0.

Table of Contents


1 Introduction


2 Systems

The main system appears first, followed by any subsystem dependency.


2.1 clack-static-asset-middleware

A cache busting static file middleware for the clack web framework.

Author

Matt Novenstern

License

MIT

Long Description

# Clack-Static-Asset-Middleware
[![Build Status](https://travis-ci.org/fisxoj/clack-static-asset-middleware.svg?branch=master)](https://travis-ci.org/fisxoj/clack-static-asset-middleware) [![Coverage Status](https://coveralls.io/repos/github/fisxoj/clack-static-asset-middleware/badge.svg?branch=master)](https://coveralls.io/github/fisxoj/clack-static-asset-middleware?branch=master)[![Quicklisp](http://quickdocs.org/badge/clack-static-asset-middleware.svg)](http://quickdocs.org/clack-static-asset-middleware/)

The static asset middleware is for handling versioned static assets. That means that, when the assets of your webapp change, it will be referred to by a different filename, allowing a browser to instantly know that it needs to download a new file. Assets are served with the maximum cache time headers set so browsers will never ask for them again.

It comes with the ‘clack-static-asset-djula-helpers‘ package which extends the djula templating language to allow inserting cache busted urls for your files easily.

## Usage

Use by wrapping your clack app in ‘clack-static-asset-middleware:*clack-static-asset-middleware*‘.

“‘lisp
(funcall clack-static-asset-middleware:*clack-static-asset-middleware*
clack-app
:root (asdf:system-relative-pathname :webapp #p"static/")
:path "static/")
“‘

It can be configured by specifying:

- ‘path‘: the path on your app that you want your assets to be served from. That is ‘https://my-webapp.com/{path}/images/some-sheep_12..532.png‘.
- ‘root‘: The root directory that your assets reside in on the filesystem.
- ‘cache-buster-function‘: A function of two arguments ‘(pathname cache-string)‘ that generates an appropriate, cache-busted name for a file. The default creates filenames like ‘images/some-sheep_12421345423fea543265cf43226512a6.png‘.
- ‘cache-unbuster-function‘: A function that takes a cache-busted url and resolves it to the un-busted filename.
- ‘filter-function‘: A function that identifies files that should not be served but are in the ‘root‘ directory anyway. It acceps a pathname and return a boolean where ‘t‘ means ’do not serve’ and ‘nil‘ means the file is good to serve. By default, it blocks files beginnig with a ‘.‘, which would be hidden on a UNIX filesystem.

Once you have done that, you can call ‘busted-uri-for-path‘ to convert a relative path on your system into an appropriate cache busted url suitable for inserting into templating and showing your friends. There is a helper package for accessing this functionality within the [Djula](https://github.com/mmontone/) templating language below.

### Real-World Usage

This middleware is not optimized to serve files. It should not be particularly slow, but it was not designed to be your CDN. In real-world situations, you should consider putting a CDN or nginx proxy in front of your app for best performance. I have not done this, yet, but it’s probably something I should work on.

Ideally, you might set this up behind an nginx reverse proxy and let it handle un-busting your URLs like so:

“‘
server {
# ...

location ~* ^/<YOUR PATH HERE>/(\w+)/([^/]+)_\d+\.(js|css|png|jpg|jpeg|gif|ico)$ {
alias <YOUR ROOT HERE>/$1/$2.$3;
add_header Vary Accept-Encoding;
expires max;
}

# ...
}
“‘
Example taken from the blog of [Ben Ripkens](http://blog.bripkens.de/2012/03/nginx-cache-busting/).

## Installation

‘clack-static-asset-middleware‘ is not yet in quicklisp, so clone it into your quicklisp ‘local-projects‘ directory. Then, run

“‘lisp
(ql:quickload :clack-static-asset-middleware)
“‘

or refer to it in your system definition

“‘lisp
(asdf:defsystem my-great-webapp
...
:depends-on (#:clack-static-asset-middleware)
..
)
“‘

## Template Helpers

Right now, there is a helper package, ‘clack-static-asset-djula-helpers‘, which provides extensions to the [Djula](https://github.com/mmontone/) templating language for inserting busted URLs into templates. Once you’ve loaded the system, there will be two new djula tags available.

- ‘asset-path‘: Inserts a busted url to the given path.
“‘
<img src="{% asset-path "images/gustywinds.jpg" %}" /> => <img src="/static/images/gustywinds_423534...a3.jpg" />
“‘
- ‘stylesheet-tag‘: Inserts a busted url conveniently inside a stylesheet tag.
“‘
{% stylesheet-tag "styles/cool.css" %} => <link rel="stylesheet" href="/static/styles/cool_a05b6...878f.css">
“‘

## Author

* Matt Novenstern (fisxoj@gmail.com)

## Copyright

Copyright (c) 2016 Matt Novenstern (fisxoj@gmail.com)

## License

Licensed under the MIT License.

Version

1.1

Dependencies
  • alexandria (system).
  • uiop (system).
  • ironclad (system).
  • cl-ppcre (system).
  • local-time (system).
  • trivial-mimes (system).
Source

clack-static-asset-middleware.asd.

Child Component

src (module).


3 Modules

Modules are listed depth-first from the system components tree.


3.1 clack-static-asset-middleware/src

Source

clack-static-asset-middleware.asd.

Parent Component

clack-static-asset-middleware (system).

Child Component

clack-static-asset-middleware.lisp (file).


4 Files

Files are sorted by type and then listed depth-first from the systems components trees.


4.1 Lisp


4.1.1 clack-static-asset-middleware/clack-static-asset-middleware.asd

Source

clack-static-asset-middleware.asd.

Parent Component

clack-static-asset-middleware (system).

ASDF Systems

clack-static-asset-middleware.

Packages

clack-static-asset-middleware-asd.


4.1.2 clack-static-asset-middleware/src/clack-static-asset-middleware.lisp

Source

clack-static-asset-middleware.asd.

Parent Component

src (module).

Packages

clack-static-asset-middleware.

Public Interface
Internals

5 Packages

Packages are listed by definition order.


5.1 clack-static-asset-middleware-asd

Source

clack-static-asset-middleware.asd.

Use List
  • asdf/interface.
  • common-lisp.

5.2 clack-static-asset-middleware

Source

clack-static-asset-middleware.lisp.

Use List

common-lisp.

Public Interface
Internals

6 Definitions

Definitions are sorted by export status, category, package, and then by lexicographic order.


6.1 Public Interface


6.1.1 Special variables

Special Variable: *asset-lookup-table*

Lookup table for files in the static asset directory. Maps relative filenames to cache-busted versions, e.g. ’style/homepage.css => style/homepage_2867f3f83a6a91ad4a19a6cd45536152.css

Package

clack-static-asset-middleware.

Source

clack-static-asset-middleware.lisp.

Special Variable: *clack-static-asset-middleware*
Package

clack-static-asset-middleware.

Source

clack-static-asset-middleware.lisp.

Special Variable: +default-cache-buster-function+

Function to make a new pathname with a cache-busting string appended. The default it to convert ‘style.css‘ to ‘style_[hex-string].css‘. You can override this by passing a different function to the middleware.

Package

clack-static-asset-middleware.

Source

clack-static-asset-middleware.lisp.

Special Variable: +default-cache-unbuster-function+

Function to undo the cache busting.

Package

clack-static-asset-middleware.

Source

clack-static-asset-middleware.lisp.

Special Variable: +default-filter-function+

Function to filter out files that would be hidden on a unix system. Namely, anything that starts with a ‘#.‘.

Package

clack-static-asset-middleware.

Source

clack-static-asset-middleware.lisp.


6.1.2 Ordinary functions

Function: busted-uri-for-path (path)

Lookup the busted resource uri for a given path. Returns the given path if none is found.

Package

clack-static-asset-middleware.

Source

clack-static-asset-middleware.lisp.


6.2 Internals


6.2.1 Special variables

Special Variable: *base-path*

Base path of the assets on the server. Maybe something like "static/".

Package

clack-static-asset-middleware.

Source

clack-static-asset-middleware.lisp.


6.2.2 Ordinary functions

Function: asset-response (relative-path root)

Generate the ‘clack‘ respone with an file or a 404. Expects ‘relative-path‘ to be a string with no leading ‘/‘.

Package

clack-static-asset-middleware.

Source

clack-static-asset-middleware.lisp.

Function: inventory-files (pathnames path root &key filter-function cache-buster-function)
Package

clack-static-asset-middleware.

Source

clack-static-asset-middleware.lisp.

Function: md5-file (pathname &key buffer digest)

Generate a string of hex digits for a given pathname.

Package

clack-static-asset-middleware.

Source

clack-static-asset-middleware.lisp.

Function: root-relative-path (pathname root)

Produces a relative pathname relative to the root of the asset directory. The string that might be specified in a template, for example.

Package

clack-static-asset-middleware.

Source

clack-static-asset-middleware.lisp.

Function: walk-directory (directory &key filter-function)

Collects all the files in ‘directory‘ except those excluded by ‘filter-function‘.

Package

clack-static-asset-middleware.

Source

clack-static-asset-middleware.lisp.


Appendix A Indexes


A.1 Concepts