aicra: all-in-config REST API

Aicra is a self-working framework coded in Go that allows anyone to create a fully featured REST API. It features type checking, authentication management through middlewares, file upload, rich argument parsing (i.e. url slash-separated, urlencoded, form-data, json), nested routes, project builder (i.e. aicra), etc.

This framework is based over some of the following concepts.

concept	explanation
meaningful defaults	Defaults and default values work without further understanding
config driven	Avoid information duplication. Automate anything that can be without losing control. Have one configuration that summarizes the whole project, its behavior and its automation flow.

A working example is available here

1. Installation

You need a recent machine with go installed.

This package has not been tested under the version 1.10.

(1) Download and install the package

$ go get -u git.xdrm.io/go/aicra

It should now be available locally and available for your imports.

(2) Compile the command-line builder

You should then compile the project builder to help you manage your projects.

$ go install git.xdrm.io/go/aicra/cmd/aicra

The executable aicra will be placed into your $GOPATH/bin folder, if added to your environment PATH it should be available as a standalone command in your terminal. If not, you can simply run $GOPATH/bin/aicra to use the command or create a symlink into /usr/local/bin or the PATH folder of your choice for less characters to type.

2. Setup a project

The default project structure for aicra is as follows :

├── main.go          - the entry point
├── manifest.json    - the configuration file
├── middleware       - middleware implementations
├── controller       - controller implementations
└── types            - custom type for the type checker

In order for your project to be run, each controller, middleware and type have to be compiled as plugins (i.e. shared objects). They can then be loaded by the server.

(1) Configuration

The whole project behavior is described inside the manifest.json file. For a better understanding of the format, take a look at this working template. This file contains information about :

• resources routes and their methods
• every input for each method (called argument)
• every output for each method
• scope permissions
• input policy : type, required/optional, default value, variable renaming, etc.

(2) Controllers

For each route, you'll have to place your implementation into the controller folder following the naming convention : add /i.go at the end of the route.

Example - /path/to/some/uri will be inside controller/path/to/some/uri/i.go.

A fully working example is available here.

(3) Middlewares

In order for your project to manage authentication, the best solution is to create middlewares, there are programs that updates a Scope according to internal or persistent (i.e. database) information and the actual http request. They are all run before each request it routed by aicra. The scope are used to match the scope field in the configuration file and automatically block non-authed requests. Scopes can also be used for implementation-specific behavior.

Each middleware must be directly inside the middleware folder.

Example - the 1-authentication middleware will be inside middleware/1-authentication/main.go.

Note - middleware execution will be ordered by name. Prefixing your middlewares with their order is a good practice.

(4) Custom types

In your configuration you will have to use built-in types (e.g. int, any, varchar), but if you want project-specific ones, you can add your own types inside the type folder. You can check what structure to follow by looking at the built-in types.

Each type must be inside a unique package directly inside the type folder. The package name is arbitrary and does not have to match the name (but it is better if it is explicit), because the Match() method already matches the name.

3. Build your project

After each controller, middleware or type edition, you'll have to rebuild the project. This can be achieved through the command-line builder.

Usage is aicra [options] /path/to/your/project.

Options:

• -c - overrides the default controllers path ; default is ./controller
• -m - overrides the default middlewares path ; default is ./middleware
• -t - overrides the default custom types path ; default is ./custom-types

For a project that does not need a different structure, you just have to run this command under your project root

$ aicra .

The output should look like

.

4. Main

The main program is pretty small, it is as followed :

package main

import (
    "log"
    "git.xdrm.io/go/aicra"
)

func main() {

	// 1. init with manifest file
	server, err := aicra.New("manifest.json")
	if err != nil {
		log.Fatalf("cannot load config : %s\n", err)
	}
	
	fmt.Printf("[Server up] 0.0.0.0:4242\n")
	// 2. Launch server
	err = server.Listen(4242)
	if err != nil {
		log.Fatalf("[FAILURE] server failed : %s\n", err)
	}
}

changelog

• human-readable json configuration
• nested routes (i.e. /user/:id: and /user/post/:id:)
• nested URL arguments (i.e. /user/:id: and /user/:id:/post/​:id:​)
• useful http methods: GET, POST, PUT, DELETE
• manage URL, query and body arguments:
  • multipart/form-data (variables and file uploads)
  • application/x-www-form-urlencoded
  • application/json
• required vs. optional parameters with a default value
• parameter renaming
• generic authentication system (i.e. you can override the built-in one)
• generic type check (i.e. implement custom types alongside built-in ones)
• built-in types
  • any - wildcard matching all values
  • int - any number (e.g. float, int, uint)
  • string - any text
  • varchar(min, max) - any string with a length between min and max
  • <a> - array containing only elements matching a type
  • <a:b> - map containing only keys of type a and values of type b (a or b can be ommited)
• generic controllers implementation (shared objects)
• response interface