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https://github.com/alex-oleshkevich/starsessions
Advanced sessions for Starlette and FastAPI frameworks
https://github.com/alex-oleshkevich/starsessions
asgi fastapi python session starlette
Last synced: about 2 months ago
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Advanced sessions for Starlette and FastAPI frameworks
- Host: GitHub
- URL: https://github.com/alex-oleshkevich/starsessions
- Owner: alex-oleshkevich
- License: mit
- Created: 2021-06-24T17:16:51.000Z (about 3 years ago)
- Default Branch: master
- Last Pushed: 2024-04-16T08:06:25.000Z (5 months ago)
- Last Synced: 2024-07-19T00:05:56.570Z (2 months ago)
- Topics: asgi, fastapi, python, session, starlette
- Language: Python
- Homepage:
- Size: 255 KB
- Stars: 86
- Watchers: 6
- Forks: 10
- Open Issues: 6
-
Metadata Files:
- Readme: README.md
- Contributing: .github/contributing.md
- License: LICENSE
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README
## Starsessions
Advanced sessions for Starlette and FastAPI frameworks
## Installation
Install `starsessions` using PIP or poetry:
```bash
pip install starsessions
# or
poetry add starsessions
```
Use `redis` extra for [Redis support](#redis).
## Quick start
See the example application in [`examples/`](examples) directory of this repository.
## Usage
1. Add `starsessions.SessionMiddleware` to your application to enable session support,
2. Configure the session store and pass it to the middleware,
3. Load the session in your view/middleware by calling `load_session(connection)` utility.
```python
from starlette.applications import Starlette
from starlette.middleware import Middleware
from starlette.responses import JSONResponse
from starlette.routing import Route
from starsessions import CookieStore, load_session, SessionMiddleware
async def index_view(request):
await load_session(request)
session_data = request.session
return JSONResponse(session_data)
session_store = CookieStore(secret_key='TOP SECRET')
app = Starlette(
middleware=[
Middleware(SessionMiddleware, store=session_store, lifetime=3600 * 24 * 14),
],
routes=[
Route('/', index_view),
]
)
```
### Cookie security
By default, the middleware uses strict defaults.
The cookie lifetime is limited to the browser session and sent via HTTPS protocol only.
You can change these defaults by changing `cookie_https_only` and `lifetime` arguments:
```python
from starlette.middleware import Middleware
from starsessions import CookieStore, SessionMiddleware
session_store = CookieStore(secret_key='TOP SECRET')
middleware = [
Middleware(SessionMiddleware, store=session_store, cookie_https_only=False, lifetime=3600 * 24 * 14),
]
```
The example above will let session usage over insecure HTTP transport and the session lifetime will be set to 14 days.
### Loading session
The session data is not loaded by default. Call `load_session` to load data from the store.
```python
async def index_view(request):
await load_session(request)
request.session['key'] = 'value'
```
However, if you try to access an uninitialized session, `SessionNotLoaded` exception will be raised.
```python
async def index_view(request):
request.session['key'] = 'value' # raises SessionNotLoaded
```
You can automatically load a session by using `SessionAutoloadMiddleware` middleware.
### Session autoload
For performance reasons, the session is not autoloaded by default. Sometimes it is annoying to call `load_session` too often.
We provide `SessionAutoloadMiddleware` class to reduce the boilerplate code by autoloading the session for you.
There are two options: always autoload or autoload for specific paths only.
Here are examples:
```python
from starlette.middleware import Middleware
from starsessions import CookieStore, SessionAutoloadMiddleware, SessionMiddleware
session_store = CookieStore(secret_key='TOP SECRET')
# Always autoload
middleware = [
Middleware(SessionMiddleware, store=session_store),
Middleware(SessionAutoloadMiddleware),
]
# Autoload session for selected paths
middleware = [
Middleware(SessionMiddleware, store=session_store),
Middleware(SessionAutoloadMiddleware, paths=['/admin', '/app']),
]
# regex patterns also supported
import re
admin_rx = re.compile('/admin*')
middleware = [
Middleware(SessionMiddleware, store=session_store),
Middleware(SessionAutoloadMiddleware, paths=[admin_rx]),
]
```
### Rolling sessions
The default behavior of `SessionMiddleware` is to expire the cookie after `lifetime` seconds after it was set.
For example, if you create a session with `lifetime=3600`, the session will be terminated exactly in 3600 seconds.
Sometimes this may not be what you need, so we provide an alternate expiration strategy - rolling sessions.
When rolling sessions are activated, the cookie expiration time will be extended by `lifetime` value on every response.
Let's see how it works for example. First, on the first response you create a new session with `lifetime=3600`,
then the user does another request, and the session gets extended by another 3600 seconds, and so on.
This approach is useful when you want to use short-timed sessions but don't want them to interrupt in the middle of
the user's operation. With the rolling strategy, a session cookie will expire only after some period of the user's inactivity.
To enable the rolling strategy set `rolling=True`.
```python
from starlette.middleware import Middleware
from starsessions import SessionMiddleware
middleware = [
Middleware(SessionMiddleware, lifetime=300, rolling=True),
]
```
The snippet above demonstrates an example setup where the session will be dropped after 300 seconds (5 minutes) of
inactivity, but will be automatically extended by another 5 minutes while the user is online.
### Cookie path
You can pass `cookie_path` argument to bind the session cookies to specific URLs. For example, to activate a session cookie
only for the admin area, use `cookie_path="/admin"` middleware argument.
```python
from starlette.middleware import Middleware
from starsessions import SessionMiddleware
middleware = [
Middleware(SessionMiddleware, cookie_path='/admin'),
]
```
All other URLs not matching the value of `cookie_path` will not receive cookies thus session will be unavailable.
### Cookie domain
You can also specify which hosts can receive a cookie by passing `cookie_domain` argument to the middleware.
```python
from starlette.middleware import Middleware
from starsessions import SessionMiddleware
middleware = [
Middleware(SessionMiddleware, cookie_domain='example.com'),
]
```
> Note, this makes session cookies available for subdomains too.
> For example, when you set `cookie_domain=example.com` then session cookie will be available on subdomains
> like `app.example.com`.
### Session-only cookies
If you want the session cookie to be automatically removed from the browser when the tab closes set `lifetime` to `0`.
> Note, this depends on browser implementation!
```python
from starlette.middleware import Middleware
from starsessions import SessionMiddleware
middleware = [
Middleware(SessionMiddleware, lifetime=0),
]
```
## Built-in stores
### Memory
Class: `starsessions.InMemoryStore`
Simply stores data in memory. The data is cleared after the server restart. Mostly for use with unit tests.
### CookieStore
Class: `starsessions.CookieStore`
Stores session data in a signed cookie on the client.
### Redis
Class: `starsessions.stores.redis.RedisStore`
Stores session data in a Redis server. The store accepts either a connection URL or an instance of `Redis`.
> Requires [redis-py](https://github.com/redis/redis-py),
> use `pip install starsessions[redis]` or `poetry add starsessions[redis]`
```python
from redis.asyncio.utils import from_url
from starsessions.stores.redis import RedisStore
store = RedisStore('redis://localhost')
# or
redis = from_url('redis://localhost')
store = RedisStore(connection=redis)
```
#### Redis key prefix
By default, all keys in Redis prefixed with `starsessions.`. If you want to change this use `prefix` argument.
```python
from starsessions.stores.redis import RedisStore
store = RedisStore(url='redis://localhost', prefix='my_sessions')
```
Prefix can be a callable:
```python
from starsessions.stores.redis import RedisStore
def make_prefix(key: str) -> str:
return 'my_sessions_' + key
store = RedisStore(url='redis://localhost', prefix=make_prefix)
```
#### Key expiration
The library automatically manages key expiration, usually you have nothing to do with it.
But for cases when `lifetime=0` we don't know when the session will be over, and we have to heuristically calculate TTL,
otherwise the data will remain in Redis forever. At this moment, we just set 30 days TTL. You can change it by
setting `gc_ttl` value on the store.
```python
from starsessions.stores.redis import RedisStore
store = RedisStore(url='redis://localhost', gc_ttl=3600) # max 1 hour
```
## Custom store
Creating new stores is quite simple. All you need is to extend `starsessions.SessionStore`
class and implement abstract methods.
Here is an example of how we can create a memory-based session store. Note, that it is important that `write` method
returns session ID as a string value.
```python
from typing import Dict
from starsessions import SessionStore
# instance of class that manages session persistence
class InMemoryStore(SessionStore):
def __init__(self):
self._storage = {}
async def read(self, session_id: str, lifetime: int) -> bytes:
""" Read session data from a data source using session_id. """
return self._storage.get(session_id, {})
async def write(self, session_id: str, data: bytes, lifetime: int, ttl: int) -> str:
""" Write session data into the data source and return session ID. """
self._storage[session_id] = data
return session_id
async def remove(self, session_id: str):
""" Remove session data. """
del self._storage[session_id]
async def exists(self, session_id: str) -> bool:
return session_id in self._storage
```
### lifetime and ttl
The `write` accepts two special arguments: `lifetime` and `ttl`.
The difference is that `lifetime` is the total session duration (set by the middleware)
and `ttl` is the remaining session time. After `ttl` seconds the data can be safely deleted from the storage.
> Your custom backend has to correctly handle cases when `lifetime = 0`.
In such cases, you don't have an exact expiration value, and you would have to find a way to extend session TTL on the storage
side, if any.
## Serializers
The library automatically serializes session data to string using JSON.
By default, we use `starsessions.JsonSerializer` but you can implement your own by extending `starsessions.Serializer`
class.
```python
import json
import typing
from starlette.middleware import Middleware
from starsessions import Serializer, SessionMiddleware
class MySerializer(Serializer):
def serialize(self, data: typing.Any) -> bytes:
return json.dumps(data).encode('utf-8')
def deserialize(self, data: bytes) -> typing.Dict[str, typing.Any]:
return json.loads(data)
middleware = [
Middleware(SessionMiddleware, serializer=MySerializer()),
]
```
## Session termination
The middleware will remove session data and cookies if the session has no data. Use `request.session.clear` to empty data.
## Regenerating session ID
Sometimes you need a new session ID to avoid session fixation attacks (for example, after successful signs-in).
For that, use `starsessions.session.regenerate_session_id(connection)` utility.
```python
from starsessions.session import regenerate_session_id
from starlette.responses import Response
def login(request):
regenerate_session_id(request)
return Response('successfully signed in')
```