Files in Django

Transcript

1. FILES IN DJANGO JOSH SCHNEIER @QUACKDUCKHELLO
2. ME INTRODUCTION ▸ Using Django since 1.3 — have mentored and onboarded a number of junior developers since then ▸ Maintainer of django-storages ▸ Talk will proceed in 3 parts: ▸ Overview of the API provided by Django ▸ Some options for deployment ▸ Writing a storage backend
3. API OVERVIEW STATIC & MEDIA FILES ▸ STATIC files are the other types of files that make up your application (e.g. CSS, JavaScript and images) ▸ MEDIA files are user uploaded files ▸ This distinction has ramifications but there are similarities as well: ▸ STATIC files might come from other 3rd party applications ▸ MEDIA files come from unknown (as well as admin) users — they don’t have the same trust model ▸ Both need to be stored somewhere and then subsequently served to users
4. API OVERVIEW STATIC FILES ▸ Used by django.contrib.staticfiles ▸ A number of settings: STATIC_ROOT, STATIC_URL, STATICFILES_DIRS, STATICFILES_STORAGE, STATICFILES_FINDERS ▸ In development (when using runserver) files are served automatically by django.contrib.staticfiles.views.serve ▸ Docs are very explicit — will refuse to run unless DEBUG = True (will talk production deployments soon) ▸ All comes together with collectstatic
5. API OVERVIEW MEDIA FILES ▸ A lot more settings: DEFAULT_FILE_STORAGE, FILE_CHARSET, FILE_UPLOAD_HANDLERS, FILE_UPLOAD_MAX_MEMORY_SIZE, FILE_UPLOAD_TEMP_DIR, FILE_UPLOAD_DIRECTORY_PERMISSIONS, FILE_UPLOAD_PERMISSIONS, MEDIA_ROOT, MEDIA_URL ▸ Having both MEDIA_ROOT & MEDIA_URLwas a bit confusing for me at first — they are analogous to STATIC_ROOT & STATIC_URL ▸ MEDIA files are not automatically served in development ▸ I include a snippet in all of my projects (taken from the docs) in development to handle this: if settings.DEBUG: urlpatterns += static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)
6. API OVERVIEW STORAGE ▸ The major unifier is that they are stored with the same API — subclasses of django.core.files.storage.Storage ▸ Core ships with FileSystemStorage ▸ Fairly straightforward interface defined _open _save delete exists listdir size url path get_valid_name get_available_name get_accessed_time get_created_time get_modified_time
7. API OVERVIEW FILES ▸ Generally working with a django.core.files.File ▸ Thin wrapper over a native file ▸ Mostly commonly seen when working with ImageField & FileField ▸ Can specify which storage to use instead of the DEFAULT_FILE_STORAGE with storage=…
8. DEPLOYMENT STATIC FILE SERVING ▸ We definitely shouldn’t use runserver to serve our files — so what’s next? ▸ We also want all the production must-haves e.g. caching headers and compression ▸ One option is to have whatever is doing your reverse proxying (nginx, apache, etc) handle this for you
9. DEPLOYMENT STATIC FILE SERVING CONT. ▸ Pros: ▸ Reduced load on your Django process ▸ Using a tool that is highly optimized for this exact task ▸ Cons: ▸ Need to have access to said reverse proxy — not always possible e.g. Heroku ▸ Fiddly and annoying configuration — hard to get right and easy to get wrong
10. DEPLOYMENT STATIC FILE SERVING CONT. ▸ Another possibility, that I’d recommend for most sites, is to use whitenoise ▸ Extremely easy to install and configure in pure Python ▸ Includes a ton of features such as gzip, brotli, hashed files, and caching headers ▸ Then put it behind a CDN such as Cloudfront and your hits to Python will be minimal — only when new content is uploaded ▸ Would not recommend serving static files out of S3 generally
11. DEPLOYMENT MEDIA FILE SERVING ▸ In this case you should not be serving your files off of the same domain as your application ▸ Untrusted content being downloaded and executed in the context of your user’s session is dangerous — same-origin policy to the rescue ▸ Use a dedicated host (and domain) or host in the cloud for scaling and redundancy ▸ Many options exist and more seem to be pop up all the time ▸ Use a library to deal with the tricky bits — I recommend django-storages ▸ Can still use a CDN
12. DEMO, ERR FUN! LET’S WRITE A STORAGE BACKEND ▸ Going to use IPFS ▸ Interplanetary File System ▸ Distributed (P2P) content-addressable versioned immutable storage ▸ AKA super cool
13. QUESTIONS?