Crate clap_verbosity_flag

Easily add --verbose and --quiet flags to CLIs using Clap.

Examples

To get --quiet and --verbose flags through your entire program, just flatten Verbosity:

use clap::Parser;
use clap_verbosity_flag::Verbosity;

#[derive(Debug, Parser)]
struct Cli {
    #[command(flatten)]
    verbosity: Verbosity,

    // ... other options
}

You can then use this to configure your logger:

let cli = Cli::parse();
env_logger::Builder::new()
    .filter_level(cli.verbosity.log_level_filter())
    .init();

Use with tracing

To use with tracing, disable the log feature flag and enable the tracing feature flag:

cargo add clap_verbosity_flag --no-default features --features tracing

Then you can use it like this:

let cli = Cli::parse();
tracing_subscriber::fmt()
    .with_max_level(cli.verbosity)
    .init();

Using --verbose and --quiet flags

The default verbosity level will cause log / tracing to only report errors. The flags can be specified multiple times to increase or decrease the verbosity level.

• silence output: -q / --quiet
• show warnings: -v / --verbose
• show info: -vv / --verbose --verbose
• show debug: -vvv / --verbose --verbose --verbose
• show trace: -vvvv / --verbose --verbose --verbose --verbose

Customizing the default log level

By default, the log level is set to Error. To customize this to a different level, pass a type implementing the LogLevel trait to Verbosity:

use clap_verbosity_flag::{Verbosity, InfoLevel};

#[derive(Debug, Parser)]
struct Cli {
    #[command(flatten)]
    verbose: Verbosity<InfoLevel>,
}

Or implement our LogLevel trait to customize the default log level and help output.

Modules

loglog

tracingtracing

Structs

DebugLevel

Default to VerbosityFilter::Debug

ErrorLevel

Default to VerbosityFilter::Error

InfoLevel

Default to VerbosityFilter::Info

OffLevel

Default to VerbosityFilter::Off (no logging)

TraceLevel

Default to VerbosityFilter::Trace

Verbosity

Logging flags to #[command(flatten)] into your CLI

WarnLevel

Default to VerbosityFilter::Warn

Enums

VerbosityFilter

A representation of the log level filter.

Traits

LogLevel

Customize the default log-level and associated help