Confu

No frills app configuration via environment or command line arguments for software written in Rust.

Why Confu? Geared towards microservices, and has minimal direct dependencies list: syn, quote, proc-macro2, proc-macro-error.

if a more user friendly command line parsing desired, there are great and proven crate alternatives. For example, Clap 👏.

Features

• at compile time (when a binary is produced for your app), captures
  • build type, i.e. debug or release
  • build version, if provided via environment variable [PREFIX]VERSION, otherwise is set to <unspecified>
• Reads configuration from either
  • environment
  • command line arguments
  • defaults
• configuration items may have an optional prefix like APP_
• each config item can be
  • required - if not provided, will panic
  • protected - will display "xxxxxxx" instead of sensitive information
  • hidden - will not be displayed at all
• Specificity: defaults -> environment -> arguments. Arguments being the most specific, will take precedence over the corresponding environment values, if such are also defined

Usage/Examples

A working example is provided in repository. And a quick usage summary here as well:

In Cargo.toml:

toml [dependencies] confu = "*"

then, a code like this:

```rust use confu::Confu; use std::env;

[derive(Confu)]

[confuprefix = "APP"]

struct Config { #[default = "postgres"] db_user: String,

#[protect]
#[default = "postgres"]
db_password: String,

#[default = "127.0.0.1"]
api_host: String,

#[require]
telemetry: String,

#[hide]
super_secret_stuff: String,

}

fn main() { let config = Config::confu(); config.show(); } ```

should produce something like this, granted that APP_VERSION="0.1.0" environment variable is also set:

```bash $ cargo run --quiet -- --app_telemetry=yes build: debug version: 0.1.0

APPDBUSER/--appdbuser=postgres (default: "postgres") APPDBPASSWORD/--appdbpassword=xxxxxxx (default: "xxxxxxx") APPAPIHOST/--appapihost=127.0.0.1 (default: "127.0.0.1") APPTELEMETRY/--apptelemetry=yes (required) ```

if a require argument was omitted, a panic will occur:

bash $ cargo run --quiet thread 'main' panicked at 'required argument APP_TELEMETRY/--app_telemetry was not provided.', examples\basic\src\config.rs:4:17 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Roadmap to v0.2.0

• [x] Write the documentation
• [x] Write the tests
• [x] Produce a better error reporting in macros
• [ ] Parse into numerical and bool types