61 lines
1.9 KiB
Markdown
61 lines
1.9 KiB
Markdown
# kaya-session-redis
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Redis-backed session storage for the Kaya web framework.
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Provides `RedisSessionStore`, a `SessionStore` implementation (from
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`kaya-session`) that persists session data in Redis, so sessions are shared
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across processes and hosts.
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## Usage
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```python
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from redis.asyncio import Redis
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from kaya.core import KayaApp, HttpContext
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from kaya.session import SessionMixin
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from kaya.session.redis import RedisSessionStore
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client = Redis(host='localhost', port=6379)
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session = SessionMixin(RedisSessionStore(client))
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app = KayaApp(mixins=[session])
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@app.GET('/')
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async def home(ctx: HttpContext):
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n = ctx.session.get('visits', 0) + 1
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ctx.session['visits'] = n
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await ctx.send_str(200, f'visits: {n}')
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```
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Sessions are stored under keys with the prefix `kaya:session:` (configurable
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via the `prefix` argument). Server-side expiry uses Redis key TTLs and slides
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on each access when the session mixin passes a `max_age`.
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## Session indexes
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`RedisSessionStore` supports `Session.add_index()`,
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`SessionStore.find_sessions()`, and `delete_by_index()`. Reverse memberships
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are Redis sets updated in the same transactional pipeline as session saves.
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They are removed on deletion, and stale members are pruned during lookups.
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Bucket keys use a SHA-256 digest of the index name and value.
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## Serialization
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Session data is serialized with `pickle` by default, so arbitrary Python
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objects can be stored. The serialized value is an envelope containing the
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session dictionary and index metadata; legacy plain-dict values are still
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accepted. A different serializer can be plugged in via the `dumps`/`loads`
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arguments:
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```python
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import json
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store = RedisSessionStore(
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client,
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dumps=lambda d: json.dumps(d).encode('utf-8'),
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loads=lambda b: json.loads(b.decode('utf-8')),
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)
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```
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**Warning:** pickle deserialization of untrusted data is unsafe. Only use the
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default serializer with a trusted Redis server.
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