aws-cli

aws-cli

An extension for urfave/cli/v3 that provides AWS-backed value sources for CLI flags, allowing you to automatically fetch configuration and secrets from AWS services.

Prerequisites

• Go 1.21+ (go)
• urfave/cli v3

Installation

go get github.com/aws-contrib/aws-cli

Packages

The project is divided into modular subpackages, allowing you to only import the AWS SDK dependencies you actually need.

Usage Overview

You can use the provided value sources inside a cli.NewValueSourceChain when defining your application's flags.

import (
    "github.com/aws-contrib/aws-cli/awssmp"
    "github.com/urfave/cli/v3"
)

func main() {
    cmd := &cli.Command{
        Flags: []cli.Flag{
            &cli.StringFlag{
                Name: "db-password",
                // Automatically fetches the parameter from AWS when parsing flags
                Sources: cli.NewValueSourceChain(
                    awssmp.Parameter("/prod/db/password"),
                ),
            },
        },
    }
}

For detailed examples, fallbacks, and configuring the AWS SDK client, please see the individual package documentation linked above.

Auto-Polling S3 Config

Value sources are fetched once, at flag-parsing time. If your S3 object holds dynamic configuration that should be reloaded without restarting the process, run a goroutine that ranges over cmd.Flags, casts each entry to *cli.StringFlag, and re-invokes its source chain via Sources.Lookup(). The polled JSON is unmarshaled into a Config value and published through atomic.Pointer[Config], so readers see a consistent snapshot without locks. Polling stops when the action's context is cancelled.

See the runnable polling example for the complete implementation.

For multiple S3-backed flags, key an atomic.Pointer per flag using sf.Name. The same pattern works with awssmp and awssm sources — each exposes a Lookup() method that is safe to call repeatedly.

Testing

The project uses Ginkgo and Gomega for testing.

To run the tests, you can use the go tool command:

go tool ginkgo ./...

License

MIT