entrypoint

eliminate main function boilerplate with this opinionated application framework/wrapper

About

entrypoint has the following design goals:

• eliminate application startup/configuration boilerplate
• help enforce application best practices

What does this crate actually do?

entrypoint wraps a user defined function with automatic configuration/setup/processing of:

• logging (via tracing)
• command-line argument parsing (via clap)
• .dotenv file processing and environment variable population/overrides (via dotenvy)
• easy application error handling (via anyhow)

The user defined function is intended to be/replace main().

Meaning, this main/entrypoint function can be written as if all the configuration/processing/boilerplate is ready-to-use. More explicitly:

• clap::Parser struct has been parsed and populated
• .dotenv files have been parsed; environment variables are ready to go
• tracing has been configured and the global subscriber has been registered

Usage

Default Config

1. Include the entrypoint prelude:

   use entrypoint::prelude::*;
   

2. Define a clap struct and derive default entrypoint trait impls:

   #[derive(clap::Parser, DotEnvDefault, LoggerDefault, Debug)]
   #[log_level(entrypoint::tracing::Level::DEBUG)]
   #[command(version, about, long_about = None)]
   struct Args {
       #[arg(short, long)]
       verbose: bool,
   }
   

3. Define an entrypoint/main function:

   #[entrypoint::entrypoint]
   fn entrypoint(args: Args) -> entrypoint::anyhow::Result<()> {
       // env::vars() already loaded-from/merged-with .dotenv file(s)
       let _my_var = env::vars("SOMETHING_FROM_DOTENV_FILE");
   
       // logging is ready to use
       info!("entrypoint::entrypoint");
   
       // args is already parsed and ready to use
       info!("verbose set to: {:?}", args.verbose);
   
       Ok(())
   }
   

Custom Config

Using the default behavior is totally reasonable, but overwriting some trait default impl(s) can provide customization.

Usage Notes

1. The entrypoint function must:
   1. Accept a clap::Parser as an input.
   2. Return entrypoint::anyhow::Result<()>.
2. #[entrypoint::entrypoint] ordering may matter when used with other attribute macros.

Documentation

For more information, refer to:

• docs.rs
• examples
• tests

Crates

entrypoint is divided into the following crates:

• entrypoint: core traits and functionality
• entrypoint_macros: convienence macros to further reduce boilerplate

Contributing

Before doing anything else: open an issue.