Configuration

Application Kit uses Bender manifests for configuration. This guide covers how to configure your service dependencies.

Bender Manifest

Create an application.json file in your project root:

{
  "name": "my_service",
  "dependencies": {
    "services": [],
    "databases": []
  }
}

Service Dependencies

Services are external HTTP APIs your application depends on.

{
  "dependencies": {
    "services": [
      {"name": "authentication", "test_value": "http://localhost:34555"}
    ]
  }
}

Required Services

Service	Purpose
authentication	Token validation service

Accessing Services

from application_kit.settings import get_service_url

# Get base URL
auth_url = get_service_url("authentication")

# Get URL with path
validate_url = get_service_url("authentication", "/validate")

Database Dependencies

Databases include Redis and PostgreSQL connections.

Redis Databases

{
  "dependencies": {
    "databases": [
      {"name": "ratelimit", "type": "redis", "database": "0"},
      {"name": "authentication_cache", "type": "redis", "database": "1"},
      {"name": "metrics_queue", "type": "redis", "database": "2", "extras": {"queue_prefix": "counter"}}
    ]
  }
}

Field	Type	Description
name	string	Dependency name used with get_redis_instance()
type	string	Must be "redis"
database	string	Redis database number (0-15)
extras	object	Additional parameters (e.g., queue_prefix)

Reserved Database IDs

To avoid conflicts between services sharing the same Redis instance, use these standardized database IDs:

Database ID	Name	Purpose
0	ratelimit	Rate limiting counters and overrides
1	authentication_cache	Cached validated tokens
2	metrics_queue	Request counting queue
3	(app-specific)	Reserved for app-specific use (e.g., Leela)
8	import_queue / general_cache	Background job queues or general caching
10	general_cache	General-purpose caching

Always specify database

Without a database field, Redis defaults to database 0. This can cause conflicts with rate limiting data. Always explicitly set the database ID.

Accessing Redis

from application_kit.settings import (
    get_redis_instance,
    get_async_redis_instance,
    get_redis_instance_and_extras,
)

# Sync Redis client
redis = get_redis_instance("authentication_cache")

# Async Redis client
redis = get_async_redis_instance("ratelimit")

# Get extras (e.g., queue_prefix)
redis, extras = get_redis_instance_and_extras("metrics_queue")
queue_prefix = extras.get("queue_prefix")

PostgreSQL Databases

{
  "dependencies": {
    "databases": [
      {"name": "default", "type": "postgresql"},
      {"name": "geo", "type": "postgresql", "extensions": ["postgis"]}
    ]
  }
}

Django Database Configuration

# settings.py
from application_kit.settings import get_django_databases

DATABASES = get_django_databases()

This automatically configures Django databases from your manifest, including PostGIS support.

Direct Database URL Access

For non-Django applications (FastAPI with SQLAlchemy, InfluxDB clients, etc.), access database URLs directly:

from application_kit.settings import get_database_url

db_url = get_database_url("default")
if db_url:
    # Build connection string for SQLAlchemy async
    connection_string = f"postgresql+asyncpg://{db_url.user}:{db_url.password}@{db_url.host}:{db_url.port}/{db_url.name}"

The BenderDbUrl object provides:

Property	Type	Description
host	str	Database hostname
port	int	Database port
user	str \| None	Username
password	str \| None	Password
name	str	Database name
kind	str	Database type (postgresql, redis, influxdb, etc.)
get_parameters()	dict	Additional URL parameters

Configuration Values

Access arbitrary configuration values from the Bender configuration backend:

from application_kit.settings import get_configuration

debug = get_configuration("DEBUG")
custom_value = get_configuration("MY_CUSTOM_CONFIG")

Environment Helpers

from application_kit.settings import (
    get_version,
    get_environment,
    get_service_name,
    get_cors_origin_whitelist,
)

# Application version (from VERSION or DD_VERSION env var)
version = get_version()

# Environment name (from ENVIRONMENT or DATADOG_ENV)
environment = get_environment()

# Service name for Datadog
service_name = get_service_name(worker_name=None)

# CORS whitelist (includes localhost in develop environment)
whitelist = get_cors_origin_whitelist()

Complete Example

{
  "name": "my_api",
  "dependencies": {
    "services": [
      {"name": "authentication", "test_value": "http://localhost:34555"}
    ],
    "databases": [
      {"name": "default", "type": "postgresql", "is_default": true},
      {"name": "ratelimit", "type": "redis", "database": "0"},
      {"name": "authentication_cache", "type": "redis", "database": "1"},
      {"name": "metrics_queue", "type": "redis", "database": "2", "extras": {"queue_prefix": "counter"}}
    ]
  }
}

This configuration provides:

• Authentication service for token validation
• PostgreSQL database for application data (marked as default)
• Redis db 0 for rate limiting counters
• Redis db 1 for authentication token caching
• Redis db 2 for metrics queue with custom prefix