Google Cloud Storage

This backend provides Django File API for Google Cloud Storage using the Python library provided by Google.

Installation

Use pip to install from PyPI:

pip install django-storages[google]

Authentication

By default this library will try to use the credentials associated with the current Google Compute Engine (GCE) or Google Kubernetes Engine (GKE) instance for authentication. In most cases, the default service accounts are not sufficient to read/write and sign files in GCS.

1. Create a service account. (Google Getting Started Guide)

  1. Create the key and download your-project-XXXXX.json file.

3. Make sure your service account has access to the bucket and appropriate permissions. (Using IAM Permissions)

4. The key must be mounted/available to your running Django app. Note: a json keyfile will work for developer machines (or other instances outside Google infrastructure).

  1. Set an environment variable of GOOGLE_APPLICATION_CREDENTIALS to path of the json file.

Alternatively, you can use the setting GS_CREDENTIALS as described below.

Getting Started

Set the default storage and bucket name in your settings.py file:

DEFAULT_FILE_STORAGE = 'storages.backends.gcloud.GoogleCloudStorage'
GS_BUCKET_NAME = 'YOUR_BUCKET_NAME_GOES_HERE'

Once you’re done, default_storage will be Google Cloud Storage:

>>> from django.core.files.storage import default_storage
>>> print default_storage.__class__
<class 'storages.backends.gcloud.GoogleCloudStorage'>

This way, if you define a new FileField, it will use the Google Cloud Storage:

>>> from django.db import models
>>> class Resume(models.Model):
...     pdf = models.FileField(upload_to='pdfs')
...     photos = models.ImageField(upload_to='photos')
...
>>> resume = Resume()
>>> print resume.pdf.storage
<storages.backends.gcloud.GoogleCloudStorage object at ...>

Settings

To use gcloud set:

DEFAULT_FILE_STORAGE = 'storages.backends.gcloud.GoogleCloudStorage'

GS_BUCKET_NAME

Your Google Storage bucket name, as a string. Required.

GS_PROJECT_ID (optional)

Your Google Cloud project ID. If unset, falls back to the default inferred from the environment.

GS_CREDENTIALS (optional)

The OAuth 2 credentials to use for the connection. If unset, falls back to the default inferred from the environment (i.e. GOOGLE_APPLICATION_CREDENTIALS)

from google.oauth2 import service_account

GS_CREDENTIALS = service_account.Credentials.from_service_account_file(
    "path/to/credentials.json"
)

GS_AUTO_CREATE_BUCKET (optional, default is False)

If True, attempt to create the bucket if it does not exist.

GS_AUTO_CREATE_ACL (optional, default is projectPrivate)

ACL used when creating a new bucket, from the list of predefined ACLs. (A “JSON API” ACL is preferred but an “XML API/gsutil” ACL will be translated.)

Note that the ACL you select must still give the service account running the GCE backend to have OWNER permission on the bucket. If you’re using the default service account, this means you’re restricted to the projectPrivate ACL.

GS_DEFAULT_ACL (optional, default is None)

ACL used when creating a new blob, from the list of predefined ACLs. (A “JSON API” ACL is preferred but an “XML API/gsutil” ACL will be translated.)

For most cases, the blob will need to be set to the publicRead ACL in order for the file to viewed. If GS_DEFAULT_ACL is not set, the blob will have the default permissions set by the bucket.

publicRead files will return a public - non-expiring url. All other files return a signed (expiring) url.

GS_DEFAULT_ACL must be set to ``publicRead`` to return a public url. Even if you set the bucket to public or set the file permissions directly in GCS to public.

GS_FILE_CHARSET (optional)

Allows overriding the character set used in filenames.

GS_FILE_OVERWRITE (optional: default is True)

By default files with the same name will overwrite each other. Set this to False to have extra characters appended.

GS_MAX_MEMORY_SIZE (optional)

The maximum amount of memory a returned file can take up (in bytes) before being rolled over into a temporary file on disk. Default is 0: Do not roll over.

GS_CACHE_CONTROL (optional: default is None)

Sets Cache-Control HTTP header for the file, more about HTTP caching can be found here

GS_LOCATION (optional: default is '')

Subdirectory in which the files will be stored. Defaults to the root of the bucket.

GS_EXPIRATION (optional: default is timedelta(seconds=86400))

The time that a generated URL is valid before expiration. The default is 1 day. Public files will return a url that does not expire. Files will be signed by the credentials provided to django-storages (See GS_CREDENTIALS).

Note: Default Google Compute Engine (GCE) Service accounts are unable to sign urls.

The GS_EXPIRATION value is handled by the underlying Google library. It supports timedelta, datetime, or integer seconds since epoch time.

Usage

Fields

Once you’re done, default_storage will be Google Cloud Storage:

>>> from django.core.files.storage import default_storage
>>> print default_storage.__class__
<class 'storages.backends.gcloud.GoogleCloudStorage'>

This way, if you define a new FileField, it will use the Google Cloud Storage:

>>> from django.db import models
>>> class Resume(models.Model):
...     pdf = models.FileField(upload_to='pdfs')
...     photos = models.ImageField(upload_to='photos')
...
>>> resume = Resume()
>>> print resume.pdf.storage
<storages.backends.gcloud.GoogleCloudStorage object at ...>

Storage

Standard file access options are available, and work as expected:

>>> default_storage.exists('storage_test')
False
>>> file = default_storage.open('storage_test', 'w')
>>> file.write('storage contents')
>>> file.close()

>>> default_storage.exists('storage_test')
True
>>> file = default_storage.open('storage_test', 'r')
>>> file.read()
'storage contents'
>>> file.close()

>>> default_storage.delete('storage_test')
>>> default_storage.exists('storage_test')
False

Model

An object without a file has limited functionality:

>>> obj1 = Resume()
>>> obj1.pdf
<FieldFile: None>
>>> obj1.pdf.size
Traceback (most recent call last):
...
ValueError: The 'pdf' attribute has no file associated with it.

Saving a file enables full functionality:

>>> obj1.pdf.save('django_test.txt', ContentFile('content'))
>>> obj1.pdf
<FieldFile: tests/django_test.txt>
>>> obj1.pdf.size
7
>>> obj1.pdf.read()
'content'

Files can be read in a little at a time, if necessary:

>>> obj1.pdf.open()
>>> obj1.pdf.read(3)
'con'
>>> obj1.pdf.read()
'tent'
>>> '-'.join(obj1.pdf.chunks(chunk_size=2))
'co-nt-en-t'

Save another file with the same name:

>>> obj2 = Resume()
>>> obj2.pdf.save('django_test.txt', ContentFile('more content'))
>>> obj2.pdf
<FieldFile: tests/django_test_.txt>
>>> obj2.pdf.size
12

Push the objects into the cache to make sure they pickle properly:

>>> cache.set('obj1', obj1)
>>> cache.set('obj2', obj2)
>>> cache.get('obj2').pdf
<FieldFile: tests/django_test_.txt>

Deleting an object deletes the file it uses, if there are no other objects still using that file:

>>> obj2.delete()
>>> obj2.pdf.save('django_test.txt', ContentFile('more content'))
>>> obj2.pdf
<FieldFile: tests/django_test_.txt>