Setting up STATIC_URL dynamically for Git users

If you don't want to refresh the browser cache each time you change your CSS and JavaScript files, or while styling images, you need to set STATIC_URL dynamically with a varying path component. With the dynamically changing URL, whenever the code is updated, the visitor's browser will force loading of all-new uncached static files. In this recipe, we will set a dynamic path for STATIC_URL when you use the Git version control system.

Getting ready

Make sure that your project is under the Git version control and you have BASE_DIR defined in your settings, as shown in the Defining relative paths in the settings recipe.

If you haven't done so yet, create the utils module in your Django project. Also, create a misc.py file there.

How to do it...

The procedure to put the Git timestamp in the STATIC_URL setting consists of the following two steps:

Add the following content to the misc.py file placed in utils/:

# utils/misc.py
import subprocess
from datetime import datetime

def get_git_changeset(absolute_path):
    repo_dir = absolute_path
    git_show = subprocess.Popen(
        "git show --pretty=format:%ct --quiet HEAD",
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE,
        shell=True,
        cwd=repo_dir,
        universal_newlines=True)
    timestamp = git_show.communicate()[0].partition(‘\n’)[0]
    try:
        timestamp = datetime.utcfromtimestamp(int(timestamp))
    except ValueError:
        return ""
    changeset = timestamp.strftime(‘%Y%m%d%H%M%S’)
    return changeset

Import the newly created get_git_changeset() function in the settings and use it for the STATIC_URL path, as follows:

# settings.py
# ... somewhere after BASE_DIR definition ...
from utils.misc import get_git_changeset
STATIC_URL = f'/static/{get_git_changeset(BASE_DIR)}/'

How it works...

The get_git_changeset() function takes the absolute_path directory as a parameter and calls the git show shell command with the parameters to show the Unix timestamp of the HEAD revision in the directory. As stated in the previous recipe, we pass BASE_DIR to the function, as we are sure that it is under version control. The timestamp is parsed, converted to a string consisting of year, month, day, hour, minutes, and seconds, returned; and included in the definition of STATIC_URL.