koin_ping_0.2.0/LLM_DEV_PROMPTS/C_GENERAL_CODE_STYLEGUIDE.md

title, last_modified

title	last_modified
Code Styleguide	2026-02-22

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1. Every repo must have a Makefile and a Dockerfile. See Repository Policies for required targets and conventions.

2. Credentials and/or secrets should never be committed to any repository, even private ones. Store secrets in environment variables, and if they are absolutely required, check on startup to make sure they are set/non-default and complain loudly if not. Exception, sometimes: public keys. (Public keys can still sometimes be secrets for operational security reasons.)

3. KISS & DRY: Keep it simple, stupid (KISS) and Don't Repeat Yourself (DRY) to minimize complexity and technical debt.

4. Composition over Inheritance: Prefer combining simple objects to build complex ones rather than creating deep class hierarchies.

5. Avoid nesting if statements. If you have more than one level of nesting, consider inverting the condition and using return to exit early.

6. Almost all services/servers should accept their configuration via environment variables. Only go full config file if absolutely necessary.

7. For services/servers, log JSON to stdout. This makes it easier to parse and aggregate logs when run under docker. Use structured logging whenever possible. You may detect if the output is a terminal and pretty-print the logs in that case.

8. Debug mode is enabled by setting the environment variable DEBUG to a non-empty string. This should enable verbose logging and such. It will never be enabled in prod.

9. For services/servers, make a healthcheck available at /.well-known/healthcheck. The response must have a Content-Type: application/json header and return a JSON object containing the service's name, uptime, and a key of "status" with a value of "ok". Return a 200 for healthy, 5xx for unhealthy.

10. If possible, for services/servers, include a /metrics endpoint that returns Prometheus-formatted metrics. This is not required for all services, but is a nice-to-have.

Bash / Shell

1. Use [[ instead of [ for conditionals.

2. Use $( ) instead of backticks.

3. Use #!/usr/bin/env bash as the shebang line. This allows the script to be run on systems where bash is not in /bin.

4. Use set -euo pipefail at the top of every script. This will cause the script to exit if any command fails, or if a variable is used before it is set.

5. Use pv for progress bars when piping data through a command.

6. Put all code in functions, even a main function. Define all functions then call main at the bottom of the file.

Docker Containers (for services)

1. Use runit with runsvinit as the entrypoint for all containers. This allows for easy service management and logging. In startup scripts (/etc/service/*/run) in the container, put a sleep 1 at the top of the script to avoid spiking the cpu in the case of a fast-exiting process (such as in an error condition). This also limits the maximum number of error messages in logs to 86400/day.

Author

@sjdev <[sj@sjdev.co(mailto:sj@sjdev.berlin)>

License

MIT. See LICENSE.