hashedassets

hashedassets is a command-line tool that copies files to filenames based on their contents. It also writes a map of what was renamed to what, so you can find your files.

Main purpose of this is that you can add a far future Expires header to your components. Using hash based filenames is a lot better than using your $VCS revision number, because users only need to download files that didn't change.

Creating some source files

First, we create a file to be hashed:

>>> system("mkdir input/")
>>> system("mkdir input/subdir/")
>>> system("mkdir maps/")
>>> with open("input/foo.txt", "w") as file:
... file.write("foo")

>>> with open("input/subdir/bar.txt", "w") as file:
... file.write("bar")

>>> system('touch -t200504072213.12 input/foo.txt')

Simple usage

>>> system("hashedassets maps/map.txt input/*.txt input/*/*.txt output/")
mkdir 'output'
cp 'input/foo.txt' 'output/C-7Hteo_D9vJXQ3UfzxbwnXaijM.txt'
cp 'input/subdir/bar.txt' 'output/Ys23Ag_5IOWqZCw9QGaVDdHwH00.txt'

>>> print open("maps/map.txt").read()
subdir/bar.txt: Ys23Ag_5IOWqZCw9QGaVDdHwH00.txt
foo.txt: C-7Hteo_D9vJXQ3UfzxbwnXaijM.txt
< BLANKLINE >

>>> system("ls output/")
C-7Hteo_D9vJXQ3UfzxbwnXaijM.txt
Ys23Ag_5IOWqZCw9QGaVDdHwH00.txt

>>> system("ls maps/")
map.txt

Logging level

If we tell the command to be quiet, it does not print what it is doing:

>>> system("hashedassets -q maps/map2.txt input/*.txt input/*/*.txt output/")

If we tell the command to be more verbose, it logs more information:

>>> system("hashedassets -vvv maps/map3.txt input/*.txt input/*/*.txt output/")
Debug level set to 10
cp 'input/foo.txt' 'output/C-7Hteo_D9vJXQ3UfzxbwnXaijM.txt'
cp 'input/subdir/bar.txt' 'output/Ys23Ag_5IOWqZCw9QGaVDdHwH00.txt'

Modification time is also preserved:

>>> old_stat = os.stat("input/foo.txt")
>>> new_stat = os.stat("output/C-7Hteo_D9vJXQ3UfzxbwnXaijM.txt")
>>> [(getattr(old_stat, prop) == getattr(new_stat, prop))
... for prop in ('st_mtime', 'st_atime', 'st_ino',)]
[True, True, False]

We can easily do this with multiple formats:

JavaScript

>>> system("hashedassets -n my_callback maps/map.js input/*.txt input/*/*.txt output/")
cp 'input/foo.txt' 'output/C-7Hteo_D9vJXQ3UfzxbwnXaijM.txt'
cp 'input/subdir/bar.txt' 'output/Ys23Ag_5IOWqZCw9QGaVDdHwH00.txt'

>>> print open("maps/map.js").read()
var my_callback = {
 "foo.txt": "C-7Hteo_D9vJXQ3UfzxbwnXaijM.txt",
 "subdir/bar.txt": "Ys23Ag_5IOWqZCw9QGaVDdHwH00.txt"
};

JSON

>>> system("hashedassets -n my_callback maps/map.json input/*.txt input/*/*.txt output/")
cp 'input/foo.txt' 'output/C-7Hteo_D9vJXQ3UfzxbwnXaijM.txt'
cp 'input/subdir/bar.txt' 'output/Ys23Ag_5IOWqZCw9QGaVDdHwH00.txt'

>>> print open("maps/map.json").read()
{
 "foo.txt": "C-7Hteo_D9vJXQ3UfzxbwnXaijM.txt",
 "subdir/bar.txt": "Ys23Ag_5IOWqZCw9QGaVDdHwH00.txt"
}

JSONP

>>> system("hashedassets -n my_callback maps/map.jsonp input/*.txt input/*/*.txt output/")
cp 'input/foo.txt' 'output/C-7Hteo_D9vJXQ3UfzxbwnXaijM.txt'
cp 'input/subdir/bar.txt' 'output/Ys23Ag_5IOWqZCw9QGaVDdHwH00.txt'

>>> print open("maps/map.jsonp").read()
my_callback({
 "foo.txt": "C-7Hteo_D9vJXQ3UfzxbwnXaijM.txt",
 "subdir/bar.txt": "Ys23Ag_5IOWqZCw9QGaVDdHwH00.txt"
});

Sass

Sass is a meta language on top of CSS.

>>> system("hashedassets -n my_callback maps/map.scss input/*.txt input/*/*.txt output/")
cp 'input/foo.txt' 'output/C-7Hteo_D9vJXQ3UfzxbwnXaijM.txt'
cp 'input/subdir/bar.txt' 'output/Ys23Ag_5IOWqZCw9QGaVDdHwH00.txt'

>>> print open("maps/map.scss").read()
@mixin my_callback($directive, $path) {
 @if $path == "subdir/bar.txt" { #{$directive}: url("Ys23Ag_5IOWqZCw9QGaVDdHwH00.txt"); }
 @else if $path == "foo.txt" { #{$directive}: url("C-7Hteo_D9vJXQ3UfzxbwnXaijM.txt"); }
 @else {
 @warn "Did not find "#{$path}" in list of assets";
 #{$directive}: url($path);
 }
}

PHP

>>> system("hashedassets -n my_callback maps/map.php input/*.txt input/*/*.txt output/")
cp 'input/foo.txt' 'output/C-7Hteo_D9vJXQ3UfzxbwnXaijM.txt'
cp 'input/subdir/bar.txt' 'output/Ys23Ag_5IOWqZCw9QGaVDdHwH00.txt'

>>> print open("maps/map.php").read()
$my_callback = array(
 "subdir/bar.txt" = > "Ys23Ag_5IOWqZCw9QGaVDdHwH00.txt",
 "foo.txt" => "C-7Hteo_D9vJXQ3UfzxbwnXaijM.txt",
)

Sed

We can also generate a sed script that does the replacements for us:

>>> system("hashedassets -n my_callback maps/map.sed input/*.txt input/*/*.txt output/")
cp 'input/foo.txt' 'output/C-7Hteo_D9vJXQ3UfzxbwnXaijM.txt'
cp 'input/subdir/bar.txt' 'output/Ys23Ag_5IOWqZCw9QGaVDdHwH00.txt'

>>> print open("maps/map.sed").read()
s/subdir\/bar\.txt/Ys23Ag_5IOWqZCw9QGaVDdHwH00\.txt/g
s/foo\.txt/C-7Hteo_D9vJXQ3UfzxbwnXaijM\.txt/g
< BLANKLINE >

We should also be able to use this directly with sed

>>> with open("replaceme.html", "w") as file:
... file.write('< a href=foo.txt >bar< /a >')

The script is then applied like this:

>>> system("sed -f maps/map.sed replaceme.html")
< a href=C-7Hteo_D9vJXQ3UfzxbwnXaijM.txt >bar< /a >

However, '.' is not treated as wildcard, so the following does not work

>>> with open("replaceme2.html", "w") as file:
... file.write('< a href=fooAtxt >bar< /a >')

>>> system("sed -f maps/map.sed replaceme2.html")
< a href=fooAtxt >bar< /a >

Specifying the type with -t

The type of the map is guessed from the filename, but you can specify it as well:

>>> system("hashedassets -t js cantguessmaptype input/*.txt input/*/*.txt output/")
cp 'input/foo.txt' 'output/C-7Hteo_D9vJXQ3UfzxbwnXaijM.txt'
cp 'input/subdir/bar.txt' 'output/Ys23Ag_5IOWqZCw9QGaVDdHwH00.txt'

Specifying the length of the filename with -l

>>> system("hashedassets -l 10 maps/shortmap.json input/*.txt input/*/*.txt output/")
cp 'input/foo.txt' 'output/C-7Hteo_D9.txt'
cp 'input/subdir/bar.txt' 'output/Ys23Ag_5IO.txt'

>>> system("rm output/C-7Hteo_D9.txt output/Ys23Ag_5IO.txt")

Specifying the digest with -d

>>> system("hashedassets -d md5 maps/shortmap.json input/*.txt input/*/*.txt output/")
cp 'input/foo.txt' 'output/rL0Y20zC-Fzt72VPzMSk2A.txt'
cp 'input/subdir/bar.txt' 'output/N7UdGUp1E-RbVvZSTy1R8g.txt'

>>> system("rm output/rL0Y20zC-Fzt72VPzMSk2A.txt output/N7UdGUp1E-RbVvZSTy1R8g.txt")

Re-using a map

The program reads in maps it created in a prior run to only copy files that haven't changed since. So, the following commands do not copy any files:

>>> system("hashedassets maps/map.scss input/*.txt input/*/*.txt output/")
>>> system("hashedassets maps/map.php input/*.txt input/*/*.txt output/")
>>> system("hashedassets maps/map.js input/*.txt input/*/*.txt output/")
>>> system("hashedassets maps/map.json input/*.txt input/*/*.txt output/")
>>> system("hashedassets maps/map.sed input/*.txt input/*/*.txt output/")
>>> system("hashedassets maps/map.jsonp input/*.txt input/*/*.txt output/")
>>> system("hashedassets maps/map.txt input/*.txt input/*/*.txt output/")

If we touch one of the input files in between, the file will be read but not copied because the hashsum is the same:

>>> system('touch -t200504072214.12 input/foo.txt')
>>> system("hashedassets maps/map.json input/*.txt input/*/*.txt output/")

If we change the file's content, it will get a new name:

>>> with open("input/foo.txt", "w") as file:
... file.write("foofoo")

>>> system("hashedassets maps/map.json input/*.txt input/*/*.txt output/")
rm 'output/C-7Hteo_D9vJXQ3UfzxbwnXaijM.txt'
cp 'input/foo.txt' 'output/QIDaFD7KLKQh0l5O6b8exdew3b0.txt'

If you then list the files in the directory, note that the old file ''output/C-7Hteo_D9vJXQ3UfzxbwnXaijM.txt'' is gone:

>>> system("ls output/")
QIDaFD7KLKQh0l5O6b8exdew3b0.txt
Ys23Ag_5IOWqZCw9QGaVDdHwH00.txt

If we remove one of the created files, it gets recreated:

>>> system("rm output/Ys23Ag_5IOWqZCw9QGaVDdHwH00.txt")
>>> system("hashedassets maps/map.json input/*.txt input/*/*.txt output/")
cp 'input/subdir/bar.txt' 'output/Ys23Ag_5IOWqZCw9QGaVDdHwH00.txt'

>>> system("ls output/")
QIDaFD7KLKQh0l5O6b8exdew3b0.txt
Ys23Ag_5IOWqZCw9QGaVDdHwH00.txt

If a file that is about to be removed because the original content changed, it isn't recreated:

>>> system("rm output/QIDaFD7KLKQh0l5O6b8exdew3b0.txt")
>>> with open("input/foo.txt", "w") as file:
... file.write("foofoofoo")
>>> system("hashedassets maps/map.json input/*.txt input/*/*.txt output/")
cp 'input/foo.txt' 'output/NdbmnXyjdY2paFzlDw9aJzCKH9w.txt'

Error handling

However, if we run this with no arguments, it fails:

>>> system("hashedassets", external=True)
Usage: hashedassets [ options ] MAPFILE SOURCE [...] DEST
< BLANKLINE >
hashedassets: error: You need to specify at least MAPFILE SOURCE and DEST

Requirements:

• Python