[Fixed]-Store static files on S3 but staticfiles.json manifest locally

Some time ago I read this article which I believe fits your case well.
In there at the last paragraph exists the following:

Where is staticfiles.json located?

By default staticfiles.json will reside in STATIC_ROOT which is the
directory where all static files are collected in.
We host all our static assets on an S3 bucket which means staticfiles.json by default would end up being synced to S3. However, we wanted it to live in the code directory so we could package it and ship it to each app server.

As a result of this, ManifestStaticFilesStorage will look for
staticfiles.json in STATIC_ROOT in order to read the mappings. We had
to overwrite this behaviour, so we subclassed ManifestStaticFilesStorage:

from django.contrib.staticfiles.storage import
ManifestStaticFilesStorage from django.conf import settings

class KoganManifestStaticFilesStorage(ManifestStaticFilesStorage):

    def read_manifest(self):
        """
        Looks up staticfiles.json in Project directory
        """
        manifest_location = os.path.abspath(
            os.path.join(settings.PROJECT_ROOT, self.manifest_name)
        )
        try:
            with open(manifest_location) as manifest:
                return manifest.read().decode('utf-8')
        except IOError:
            return None

With the above change, Django static template tag will now read the
mappings from staticfiles.json that resides in project root directory.

Haven’t used it myself, so let me know if it helps!

The answer of @John and Kogan is great but doesn’t give the full code needed to make this work: As @Danra mentioned you need to also save the staticfiles.json in the source folder to make this work. Here’s the code I’ve created based on the above answer:

import json
import os
from django.conf import settings
from django.core.files.base import ContentFile
from django.core.files.storage import FileSystemStorage

from whitenoise.storage import CompressedManifestStaticFilesStorage
# or if you don't use WhiteNoiseMiddlware:
# from django.contrib.staticfiles.storage import ManifestStaticFilesStorage


class LocalManifestStaticFilesStorage(CompressedManifestStaticFilesStorage):
    """
    Saves and looks up staticfiles.json in Project directory
    """
    manifest_location = os.path.abspath(settings.BASE_DIR)  # or settings.PROJECT_ROOT depending on how you've set it up in your settings file.
    manifest_storage = FileSystemStorage(location=manifest_location)

    def read_manifest(self):

        try:
            with self.manifest_storage.open(self.manifest_name) as manifest:
                return manifest.read().decode('utf-8')
        except IOError:
            return None

    def save_manifest(self):
        payload = {'paths': self.hashed_files, 'version': self.manifest_version}
        if self.manifest_storage.exists(self.manifest_name):
            self.manifest_storage.delete(self.manifest_name)
        contents = json.dumps(payload).encode('utf-8')
        self.manifest_storage._save(self.manifest_name, ContentFile(contents))

Now you can use LocalManifestStaticFilesStorage for your STATICFILES_STORAGE. When running manage.py collectstatic, your manifest will be saved to your root project folder and Django will look for it there when serving the content.

If you have a deployment with multiple virtual machines, make sure to run collectstatic only once and copy the staticfiles.json file to all the machines in your deployment as part of your code deployment. The nice thing about this is that even if some machines don’t have the latest update yet, they will still be serving the correct content (corresponding to the current version of the code), so you can perform a gradual deploy where there is a mixed state.

There is Django ticket #27590 that addresses this question. The ticket has a pull request that implements a solution, but it has not been reviewed yet.