schildwall
v0.3.2
Published
gateway for microservice infrastructures
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Schildwall
Schildwall is a service to manage security and accessibility of API-Networks. It aims to provide a modular, simple way of building complex gateways for big APIs. It supports
- Custom Middleware
- Multiple Endpoints
installation
npm i --save @vampyreio/schildwall
How To Use
The example can be ran using 'npm run-script example' and starts a proxy server on port 8000 with an endpoint
/test/
which points to localhost:8888
// gateway.class.ts
import { ListenerErrorHandler, GatewayApp, MasterGateway } from '@vampyreio/schildwall';
import { HeaderMiddleware } from './app/middleware';
@GatewayApp({
log: true,
listenerErrorHandler: new ListenerErrorHandler,
endpoints: [
{ endpoint: 'http://localhost:58', name: 'local58' },
{ endpoint: 'http://google.com', name: 'google' },
],
middlewares: [new HeaderMiddleware()],
})
export class Gateway extends MasterGateway { }
// index.ts
import { Gateway } from './gateway.class';
const gateway = new Gateway();
async function bootstrap() {
const server = await gateway.init();
server.listen(3000);
}
If the gateway now runs on localhost:8000
, a request to Google with path /search would be made with
GET /google/search => GET http://google.com/search
GET /local58/entity/abcde => GET http://localhost:58/entity/abcde
because the first parameter of the path will be mapped onto the provided endpoint list and cut from the incoming url.
Middleware
Defining a Middleware
Middleware can be attached to the gateway easily.
A Middleware contains methods that control what it should do on startup, on shutdown and on execution.
It has access to the servers request and response via the ctx
object.
to let a header block the request and answer it itself with an error, it's not required to set the answer manually. Schildwall provides Error Objects for all 4xx and 5xx errors. when such an error is thrown, an internal error handler does this itself. It will me overwritable in upcoming versions to allow manual error handling.
Middleware will be executed in the order of binding.
In upcoming versions, middlewares will be able to pass data to following middlewares.
import {Middleware, IGatewayContext, BadGatewayException} from '../lib';
/**
* checks for a 'kill-me' header and if it is true, throw an exception
*/
class HeaderScanner extends Middleware {
/**
* executes when a request enters
*/
public async execute(ctx: IGatewayContext): Promise<any> {
if (ctx.request.headers['kill-me'] === 'true') {
throw new BadGatewayException('kill-me header was found');
}
}
/**
* executes when a middleware is bound
*/
public async start(): Promise<any> {
// Setup, initialisation, precondition checking, ...
}
/**
* executes when the server should stop
*/
public async stop(): Promise<any> {
// Cleanup, stopping processes, deletions, ...
}
}
Handle HTTP-Errors manually
If you want to futher manipulate how your gateway behaves when an error is thrown, you can insert a custom error handler. Error classes implement the MiddlewareErrorHandler which takes following parameters:
errorCodeToCatch: number
is the error code for which the error should be handled.execute: (ctx: IGatewayContext, error: HttpError) => Promise<void>
is the handler itself.
In future versions, instead of a manual error code, an error class could be passed by a decorator function
import { GatewayApp, MasterGateway, ListenerErrorHandler, Middleware, IGatewayContext, BadGatewayException, MiddlewareErrorHandler, HttpError } from '../lib';
/**
* handles 502 errors
*/
class MyFiveZeroTwo implements MiddlewareErrorHandler {
public errorCodeToCatch: number = 502;
public async execute(ctx: IGatewayContext, error: HttpError) {
ctx.response.write('There is actually text in this reply!');
ctx.response.statusCode = 502;
return ctx.response.end();
}
}
@GatewayApp({
log: true,
listenerErrorHandler: new ListenerErrorHandler,
endpoints: [
{ endpoint: 'http://localhost:3000', name: 'mock' }
],
middlewares: [new HeaderScanner()],
middlewareErrorHandlers: [new MyFiveZeroTwo()],
})
class Gateway extends MasterGateway { }
const gateway = new Gateway();
gateway.init().then((data) => {
data.server.listen(8000);
});
API
Schildwall supports accessing and manipulating the gateway via an controlling API. Following routes are currently supported:
Miidleware
- [x]
GET /middlewares
- Lists metadata about - [ ]
GET /middlewares/:middlewareId'
- list metadata of a specific middleware - [ ]
POST /middleware/:middlewareId/toggle
- starts or stops a middleware - [ ]
PATCH /middleware/:middlewareId
- changes a middlewares settings - [ ]
DELETE /middleware/:middlewareId
- removes a selected middlware
Endpoints
- [x]
GET /endpoints
- Lists endpoints - [ ]
GET /endpoints/:endpointId
- describes a single endpoint - [x]
POST /endpoints
- Creates a new Endpoint Params:
endpoint
: an url to a new endpointname
: is used as prefix in the gateway
Minimal with API
@GatewayApp({
log: true,
listenerErrorHandler: new ListenerErrorHandler,
endpoints: [
{ endpoint: 'http://localhost:3000', name: 'mock' }
],
})
class Gateway extends MasterGateway { }
const gateway = new Gateway();
gateway.init().then((data) => {
// create Server
data.server.listen(8000);
// create API
const api = new GatewayApiServer(data.manager as ListenerManager).run(8081);
});