Environment Configuration Module

Overview

The multicast.env module provides environment-based configuration for the multicast package, allowing runtime customization of network settings through environment variables.

Environment Variables

Variable	Default	Description
`MULTICAST_PORT`	59259	Port number for multicast communication (49152-65535)
`MULTICAST_GROUP`	“224.0.0.1”	Primary multicast group address (224.0.0.0/4)
`MULTICAST_GROUPS`	-	Space-separated list of additional multicast addresses
`MULTICAST_TTL`	1	Time-to-live value (1-126)
`MULTICAST_BIND_ADDR`	“0.0.0.0”	Address to bind to
`MULTICAST_BUFFER_SIZE`	1316	Receive buffer size in bytes

Usage

Basic Configuration

import os  # used to set environment

# Set custom configuration
os.environ['MULTICAST_PORT'] = '50000'
os.environ['MULTICAST_GROUP'] = '224.0.0.2'

# see os.environ['MULTICAST_GROUPS'] for multi-group config

# Uncommonly there is need to increase TTL and BUFFER size,
# however users probably want raw sockets in those cases.
# os.environ['MULTICAST_TTL'] = '2'  # May harm your own bandwidth when increasing
# os.environ['MULTICAST_BUFFER_SIZE'] = '2048'  # Expect increased data loss when increasing

# Configuration loads on import
import multicast

Multiple Group Configuration

# Join multiple multicast groups
os.environ['MULTICAST_GROUPS'] = '224.0.0.1 224.0.0.2 224.0.0.3'
# Configuration loads on import
import multicast

# load config
from multicast.env import load_config
config = load_config()

# you can now access the configuration
# e.g.
print(config['groups'])  # ['224.0.0.1', '224.0.0.2', '224.0.0.3']

(changing the resulting config values only causes the setting to lose its special value, and does not actually update Multicast after import)

Configuration Details

Port Configuration

Valid range: 49152-65535 (dynamic/private ports)
Invalid values trigger a warning and fall back to default
Example:
```
os.environ['MULTICAST_PORT'] = '50000'
```

Group Configuration

Must be valid multicast addresses (224.0.0.0/4)
Invalid addresses trigger a warning and fall back to default

Example:

os.environ['MULTICAST_GROUP'] = '224.0.0.2'

TTL Configuration

Valid range: 1-126 (as per RFC-1112)
Also sets socket default timeout
Example:
```
os.environ['MULTICAST_TTL'] = '2'
```

Buffer Size Configuration

Must be positive integer
Invalid values trigger a warning and fall back to default