Redis

This extension provides support for connecting to Redis servers. It registers the redis.asyncio.Redis service.

Usage

First install the redis extra:

pip install selva[redis]

Define the configuration properties:

configuration/settings.yaml

extensions:
  - selva.ext.data.redis # (1)

data:
  redis:
    default: # (2)
      url: redis://localhost:6379/0
    other: # (3)
      url: redis://localhost:6379/1

1. Activate the sqlalchemy extension
2. "default" connection will be registered without a name
3. Connection registered with name "other"

Inject the Redis service:

from typing import Annotated
from redis.asyncio import Redis
from selva.di import service, Inject


@service
class MyService:
    # default service
    redis: Annotated[Redis, Inject]

    # named service
    other_redis: Annotated[Redis, Inject(name="other")]

Redis connections can also be defined with username and password separated from the url, or even with individual components:

configuration/settings.yaml

data:
  redis:
    url_username_password: # (1)
      url: redis://localhost:6379/0
      username: user
      password: pass

    individual_components: # (2)
      host: localhost
      port: 6379
      db: 0
      username: user
      password: pass

1. Username and password separated from the redis url
2. Each component defined individually

Using environment variables

configuration/settings.yaml

data:
  redis:
    default:
      url: "${REDIS_URL}" # (1)

    other: # (2)
      url: "${REDIS_URL}"
      username: "${REDIS_USERNAME}"
      password: "${REDIS_PASSWORD}"

    another: # (3)
      host: "${REDIS_HOST}"
      port: ${REDIS_PORT}
      db: "${REDIS_DB}"
      username: "${REDIS_USERNAME}"
      password: "${REDIS_PASSWORD}"

1. Can be define with just the environment variable SELVA__DATA__REDIS__DEFAULT__URL
2. Can be defined with just the environment variables:
   • SELVA__DATA__REDIS__OTHER__URL
   • SELVA__DATA__REDIS__OTHER__USERNAME
   • SELVA__DATA__REDIS__OTHER__PASSWORD
3. Can be defined with just the environment variables:
   • SELVA__DATA__REDIS__ANOTHER__HOST
   • SELVA__DATA__REDIS__ANOTHER__PORT
   • SELVA__DATA__REDIS__ANOTHER__DB
   • SELVA__DATA__REDIS__ANOTHER__USERNAME
   • SELVA__DATA__REDIS__ANOTHER__PASSWORD

Example

application/controller.pyconfiguration/settings.yaml

from typing import Annotated

from redis.asyncio import Redis

from asgikit.responses import respond_json

from selva.di import Inject
from selva.web import controller, get


@controller
class Controller:
    redis: Annotated[Redis, Inject]

    async def initialize(self):
        await self.redis.set("number", 0, nx=True, ex=60)

    @get
    async def index(self, request):
        number = await self.redis.incr("number")
        await respond_json(request.response, {"number": number})

data:
  redis:
    default:
      url: "redis://localhost:6379/0"

Configuration options

Selva offers several options to configure Redis. If you need more control over the SQLAlchemy services, you can create your own redis.asyncio.Redis outside of the DI context.

The available options are shown below:

data:
  redis:
    default:
      url: ""
      host: ""
      port: 6379
      db: 0
      username: ""
      password: ""
      options: # (1)
        socket_timeout: 1.0
        socket_connect_timeout: 1.0
        socket_keepalive: false
        socket_keepalive_options: {}
        unix_socket_path: ""
        encoding: ""
        encoding_errors: "strict" # or "ignore", "replace"
        decode_responses: false
        retry_on_timeout: false
        retry_on_error: []
        ssl: false
        ssl_keyfile: ""
        ssl_certfile: ""
        ssl_cert_reqs: ""
        ssl_ca_certs: ""
        ssl_ca_data: ""
        ssl_check_hostname: false
        max_connections: 1
        single_connection_client: false 
        health_check_interval: 1
        client_name: ""
        lib_name: ""
        lib_version: ""
        auto_close_connection_pool: false
        protocol: 3
        retry:
          retries: 1
          supported_errors: [] # (2)
          backoff: # (3)
            no_backoff:
            constant:
              backoff: 1
            exponential:
              cap: 1
              base: 1
            full_jitter:
              cap: 1
              base: 1
            equal_jitter:
              cap: 1
              base: 1
            decorrelated_jitter:
              cap: 1
              base: 1

1. options values are described in redis.asyncio.Redis.
2. Dotted path to python classes.
3. Only one option in backoff should be set.