Isolated Python script that filters and persists a predefined set of environment variables (TRANSMISSION_*, TR_*, WEBPROXY_*, and a few others) into a shell script file for later sourcing. Uses argparse for the output path and set operations for efficient filtering. This pattern is reusable in any multi-process Docker container where environment variables need to be preserved across exec boundaries (e.g., from init to child processes). The script is self-contained, has no internal module dependencies, and can be extracted with minimal modification.

Python script that reads a default JSON settings file, overrides values from environment variables (with type coercion to match the setting's expected type, including booleans and numerics), and writes the result to an output file. It gracefully falls back to the default file if the output file is missing or corrupt. This is a clean, reusable pattern for runtime configuration injection in any application that uses JSON configuration files. The script is self-contained with no internal dependencies other than standard library modules.

Bash script that modifies an OpenVPN configuration file to match container-specific requirements (e.g., auth-user-pass path, CA certificate paths, ping/exit options, resolv-retry, TLS crypt paths, verbosity, signal remapping, and failure detection). Each modification is controlled by a separate CONFIG_MOD_* environment variable, making the script highly configurable and reusable. The use of sed for path manipulation and conditional appending demonstrates a systematic approach to config file patching. Could be adapted for other config file types that require similar runtime adjustments.