UI5 middleware for CF destinations

> 👋 This is a community project and there is no official support for this package! Feel free to use it, open issues, contribute, and help answering questions.

Middleware for ui5-server, making destinations configured in SAP CF available for local development using the http-proxy-middleware.

Prerequisites

• Requires at least @ui5/cli@3.0.0 (to support specVersion: "3.0")

> ⚠️ UI5 Tooling Compatibility > All releases of this tooling extension using the major version 3 require UI5 Tooling V3. Any previous releases below major version 3 (if available) also support older versions of the UI5 Tooling. But the usage of the latest UI5 Tooling is strongly recommended!

Install

npm install ui5-middleware-cfdestination --save-dev

Configuration options (in $yourapp/ui5.yaml)

• debug: ``, default: false
  verbose logging

• port: ``, default: 5000
  port to run the underlying approuter on

• xsappJson: ``, default: "./xs-app.json"
  path to the cf-style approuter configuration file xs-app.json ℹ️ the regex for the destination routes must match the pattern : /[^/]*\/(.*\/)?[^/]*/, e.g. "^/backend/(.*)$" or "^/index.html"

• destinations: ``, default: []

  • name: destination name, matching the one used in routes in xs-app.json
  • url: URI to the host to "proxy" to

  alternatively the destinations can also be defined in a .env file. They need to be in encoded in a single JSON string
  e.g.

  xsapp_dest = [{"name": "destination-name", "url": ""}]
  

  To use these destinations they need to passed to the destinations option as a string "$env:" (e.g. destinations: "$env:xsapp_dest")

• allowServices: ``, default: false
  allow BTP services to be used at runtime that are configured in xs-app.json
  (requires an authenticated BTP session!)

• authenticationMethod: "none" || "route", default: "none"
  whether to equip routes with authentication

• allowLocalDir: ``, default: false
  allow static assets to be picked up by the included approuter; defaults to false as usually all local files/assets are supposedly served by ui5-server

• rewriteContent: ``, default: true
  enables/disables rewriting of the content by replacing the proxied url in the response body with the server url

• rewriteContentTypes: ``, default: ["text/html", "application/json", "application/atom+xml", "application/xml"]
  defines the content types which are included for rewriting the content by enabling the rewriteContent option

• extensions: ``, default: [] - a list of extensions to be required and injected into the local approuter instance

  • module: - local module path (must start with ./): "./my-local-extension.js" or a module from an npm package: "@my-scope/my-package/my-extension.js"
  • parameters: >, optional - a map of parameters given as key value pairs which will be injected into the handler function of the extension as the last (4th) argument (function(req, res, next, params), remark: handler functions with more than 3 arguments will not be called for regular extensions only for these extensions!)

• disableWelcomeFile: ``, default: false experimental disables the welcome file handling of the approuter based on the welcomeFile property in the xsappJson file

• appendAuthRoute: ``, default: false experimental if true the middleware adds a custom route for all HTML pages to trigger authentication:

  {
    "source": "^/([^.]+\\.html?(?:\\?.*)?)$",
    "localDir": relativeSourcePath,
    "target": "$1",
    "cacheControl": "no-store",
    "authenticationType": "xsuaa"
  }
  

• enableWebSocket: ``, default: false experimental enables support for proxying web sockets, will be also automatically detected from xs-app.json

Usage

1. Define the dependency in $yourapp/package.json:

"devDependencies": {
    // ...
    "ui5-middleware-cfdestination": "*"
    // ...
}

2. configure it in $yourapp/ui5.yaml:

server:
  customMiddleware:
    - name: ui5-middleware-cfdestination
      afterMiddleware: compression
      configuration:
        authenticationMethod: "none" # "none" || "route", default: "none"
        allowServices: true # allows BTP services like SAP IoT to be used 
        debug: true
        port: 1091
        xsappJson: "xs-app.json"
        destinations:
          # check that the destination name (here: "backend") matches your router in xs-app.json
          - name: "backend"
            url: "https://services.odata.org/V4/(S(fdng4tbvlxgzpdtpfap2rqss))/TripPinServiceRW/"

3. put the cf routing config file xs-app.json in the location of $yourapp you specified above (xsappJson) -
   recommendation is to put it at the root / of your UI5 app!

How it works

The middleware wraps the @sap/approuter npm module that is used in the SAP BTP CloudFoundry environment for serving UI5 applications, including proxying the configured destinations.

During development, the approuter is started on a configurable port, running alongside the regular local ui5-server. When a call to a URL destination is detected at $webserver/destination, it is proxied to $approuter:$port via request.

Using approuter extensions

The ui5-middleware-cfdestination allows using approuter extensions. It is possible to pass parameters to handler functions of the extensions as a 4th argument of the handler function.

The configuration of the extensions in the ui5.yaml looks like that:

    - name: ui5-middleware-cfdestination
      afterMiddleware: compression
      configuration:
        extensions:
          - module: ./approuter-local-ext.js
            parameters:
              userId: mustermann@ui5.com

And in the approuter-local-ext.js you can consume the parameters like that:

module.exports = {
    insertMiddleware: {
        beforeRequestHandler: [
            {
                path: '/',
                handler: function forwardUserInfo(req, res, next, params) {
                    res.setHeader('x-user-id', params?.userId || "unknown@ui5.com")
                    next()
                }
            }
        ]
    }
}

Keep in mind that the 4th parameter doesn't work for the regular approuter extensions and the handler function will not be called when having more than 3 arguments.

Misc/FAQ

q: does authentication on destinations
a: yes, works 🥳

• prerequisite: a default-env.json file at the root / of your UI5 app Bespoken default-env.json file can be obtained via the Default Env CLI Plugin
• ui5.yaml > server > customMiddlware > ui5-middleware-cfdestination: set authenticationMethod to route (see config example above)
• xs-app.json (also at the root / of your UI5 app):
  • set authenticationMethod to route
  • in the route with the desired protected authentication, set authenticationType to xsuaa

see ./test/auth/**/* for example files for the above!

q: what's allowLocalDir for?
a: allows to protect local static assets (e.g. html files) -in addition to destinations- with approuter as well.
see test/auth/xs-app-with-localDir.json for an example!

License

This work is dual-licensed under Apache 2.0 and the Derived Beer-ware License. The official license will be Apache 2.0 but finally you can choose between one of them if you use this work.

When you like this stuff, buy @vobu a beer or buy @pmuessig a coke when you see them.