kragin

README

⚠️ This project isn't stable at the moment. Use in production at your own risk!

kragin 🚀

Version: v0.3.1
Description: The package provides a set of tools for developing KrakenD plugins.
Compatibility: package dependency compatibility version and KrackenD (v0.3.1 <-> v2.6.1)

Welcome to kragin! This repository contains various helper packages that simplify plugin creation for the KrakenD API Gateway.

Features ✨

• Log: Minimalistic logging interface + a no-op implementation.
• Populator: Struct field populator with tag-based configuration loading.
• Plugin: Easy-to-use “modifier” helpers for requests/responses.
• Registerer: Tools to register custom logic or transformations in Krakend.
• Wrapper: Utilities for request manipulation (body reading, form parsing, headers, etc.).

Installation 🔧

To use kragin in your own Go module, run:

go get github.com/dumb-tech/kragin@v0.3.1

Then import the packages you need:

package yourplugin

import (
    "github.com/dumb-tech/kragin/log"
    "github.com/dumb-tech/kragin/populator"
    "github.com/dumb-tech/kragin/plugin"
    "github.com/dumb-tech/kragin/registerer"
    "github.com/dumb-tech/kragin/wrapper"
)

Packages Overview 📑

1. log

Defines a Logger interface with typical logging methods:

type Logger interface {
    Debug(v ...any)
    Info(v ...any)
    Warning(v ...any)
    Error(v ...any)
    Critical(v ...any)
    Fatal(v ...any)
}

Includes a NoopLogger that does nothing (useful for testing or quiet modes). If you'll implement RegisterLoggermethod then no-op logger is useful for wait before this method will be called by KrakenD.

2. populator

Allows you to populate struct fields from a map[string]any using struct tags:

// Example struct
type Config struct {
    Host string `krakend:"host,required=true"`
    Port int    `krakend:"port,default=8080"`
}

// Usage
cfg := &Config{}
err := populator.PopulatePluginConfig(myConfigStore, "myconfig", cfg)
// Now cfg.Host, cfg.Port, etc. are populated!

• Supports default values (default=...)
• Supports required fields (required=true)
• Supports nested structs

3. plugin

Helps create plugin modifiers for request/response transformations:

p := plugin.NewModifier("my-awesome-plugin", "v1.0.0")

func (app *Application) requestHandlerFunc(config configuration.Configuration, deps *dependencies) func(any) (any, error) {
    return func(request any) (any, error) {
        r, ok := request.(wrapper.Request)
        if !ok {
            return request, wrapper.ErrUnknownRequestDataType(request)
        }
        req := wrapper.Modifier(r)
        
        req.SetHeader("X-Custom-Secret-Key", "my-secret-key")
        
        return req, nil
    }
}

RequestHandler and ResponseHandler let you add request/response modifiers. Under the hood, uses registerer.ModifierRegisterer.

4. registerer

Core interfaces and helper types for plugin registration in Krakend:

• Registerer interface for modifiers, handlers, clients.
• ModifierRegisterer for adding request/response modifiers or custom ones.

5. wrapper

Utilities for working with incoming requests:

• Request interface to get context, headers, params, body, etc.
• RequestWrapper for reading/changing the body, manipulating query params, and more.

Contributing 🤝

We ❤ contributions! Feel free to open issues or submit pull requests.

License 📄

This project is licensed under the GNU General Public License v3.0 (GPLv3).

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