Reusable Command Line Options

for spf13/cobra-based CLI tools

This package provides reusable command line options and configuration patterns for Carabiner CLI tools. It defines the OptionsSet interface for composable CLI flag management and provides common option sets that can be shared across multiple commands and applications.

Available OptionsSets

log - Logging Configuration

Package: github.com/carabiner-dev/command/log

Provides structured logging configuration with --log-level flag supporting debug, info, warn, and error levels. Includes WithLogger(ctx) method to initialize and inject logger into context.

Usage:

import "github.com/carabiner-dev/command/log"

logOpts := &log.Options{}

rootCmd := &cobra.Command{
    Use: "myapp",
    PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
        ctx, err := logOpts.WithLogger(cmd.Context())
        if err != nil {
            return err
        }
        cmd.SetContext(ctx)
        return nil
    },
}

logOpts.AddFlags(rootCmd)

keys - Public Key File Management

Package: github.com/carabiner-dev/command/keys

Provides public key file path configuration with --key/-k flag. Validates key file existence and parses keys into key.PublicKeyProvider instances.

Usage:

import "github.com/carabiner-dev/command/keys"

keyOpts := &keys.Options{}

verifyCmd := &cobra.Command{
    Use: "verify",
    RunE: func(cmd *cobra.Command, args []string) error {
        providers, err := keyOpts.ParseKeys()
        if err != nil {
            return err
        }
        // Use providers for verification...
        return nil
    },
}

keyOpts.AddFlags(verifyCmd)

output - Output File Management

Package: github.com/carabiner-dev/command/output

Provides output file path configuration with --output/-o flag. Returns an io.Writer that writes to the specified file or defaults to STDOUT.

Usage:

import "github.com/carabiner-dev/command/output"

outOpts := &output.Options{}

exportCmd := &cobra.Command{
    Use: "export",
    RunE: func(cmd *cobra.Command, args []string) error {
        writer, err := outOpts.GetWriter()
        if err != nil {
            return err
        }
        // Write output to file or STDOUT...
        fmt.Fprintln(writer, "data")
        return nil
    },
}

outOpts.AddFlags(exportCmd)

subject - Attestation Subjects

Package: github.com/carabiner-dev/command/subject

Provides the --subject/-s flag to read attestation subjects from the command line. Each value is either a digest in algorithm:value form or the path to a file, which gets hashed. Every algorithm name from the in-toto DigestSet spec is accepted (sha256, sha1, sha512, sha3_256, gitCommit, gitTree, gitBlob, gitTag, dirHash, ...), matched case-insensitively and normalized to the canonical spelling. Strings shaped like a digest are never looked up as files, so a malformed digest is reported instead of being mistaken for a path.

subject.ParseDigest can also be used on its own to parse a single algorithm:value string.

Usage:

import "github.com/carabiner-dev/command/subject"

subjectOpts := &subject.Options{}

attestCmd := &cobra.Command{
    Use: "attest",
    PreRunE: func(cmd *cobra.Command, args []string) error {
        return subjectOpts.Validate()
    },
    RunE: func(cmd *cobra.Command, args []string) error {
        descriptors, err := subjectOpts.ResourceDescriptors()
        if err != nil {
            return err
        }
        // Use the in-toto resource descriptors as subjects...
        return nil
    },
}

subjectOpts.AddFlags(attestCmd)

Contributing

This goal of this package is to to keep reusable sets of flags that have a high reuse incidence. We try to keep the dependency tree as small as possible. It is expected to mature slowly.

Feel free to file issues or suggestions if you find it useful.

This software is released under the Apache-2.0 license, paches are also welcome.