Middleware

Table of contents

1. Default Middleware
2. Health Middleware
3. ValidateBody and ValidateQueryString Middlewares
4. Metrics Middleware
5. Add Visitor Middleware
   1. Options
6. Growthbook middleware

Default Middleware

Orka adds by default the following middleware:

• addRequestId (adds ctx.state.requestId from header config.traceHeaderName)
• addRequestContext (enabled by default see request-context )
• koa-bodyparser
• riviere
• errorHandler (Handles errors thrown in any middleware added afterwards)
• koa-compress
• koa2-cors
• parseQuerystring (Uses qs and adds an object to ctx.state.query with the parsed attributes)
• addVisitorId (adds a visitorId in ctx.state.visitor from cookie ctx.visitor.cookie)

Any middlewares you add in beforeMiddleware go before this list. Any middlewares you add in afterMiddleware go after this list. Orka also adds a last middleware (after your afterMiddleware) for routing.

Health Middleware

It supports a health middleware that currently checks the availablity of mongo configuration and responds wheather the connectivity with the underlying database is stable. This is essential for liveness probes of several cloud providers such as K8s.

Example route configuration

const { middlewares: { health } } = require('@workablehr/orka');

module.exports = {
  get: {
    '/health': health,
    '/users': async (ctx, next) => {
      ctx.body = await User.find();
    }
  }
};

ValidateBody and ValidateQueryString Middlewares

It supports validation middlewares for both body or query string parameters using the joi validation module. joi is now a dependency of orka.

Example route configuration

const {
  middlewares: { validateBody, validateQueryString }
} = require('@workablehr/orka');

module.exports = {
  get: {
    '/users': [
      validateQueryString(SOME_SCHEMA),
      async (ctx, next) => {
        // Do something
      }
    ]
  },
  post: {
    '/users': [
      validateBody(SOME_SCHEMA),
      async (ctx, next) => {
        // Do something
      }
    ]
  }
};

Metrics Middleware

It supports exporting custom application metrics that can be picked by Prometheus. In order to use this middleware you should also enable the prometheus plugin described in the following section.

Example route configuration

const {
  middlewares: { metrics }
} = require('@workablehr/orka');

module.exports = {
  get: {
    '/metrics': metrics,
    '/users': async (ctx, next) => {
      ctx.body = await User.find();
    }
  }
};

Add Visitor Middleware

This middleware checks request’s cookies and extract the cookie with name config.visitor.cookie, it parses it and add it to ctx.state.visitor.

Options

config.visitor.enabled

If this is set to false, orka will not this middleware. Defaults to true.

config.visitor.cookie

This is the cookie name that the middleware will try to get/set. Defaults to wmc.

config.visitor.setCookie

If this is set to true, the middleware will create and add a new visitor cookie with name config.visitor.cookie. Defaults to false.

config.visitor.maxAge

Requires: config.visitor.setCookie=true

This is the cookie’s max age. Defaults to 7d.

config.visitor.secure

Requires: config.visitor.setCookie=true

It forces secure cookies in context. Use this when you only want to use secure=true. Defaults to true.

config.visitor.getCookieDomain

Requires: config.visitor.setCookie=true

You can use this method to set the preferable cookie domain.

Default:

// If hostname is www.google.com the cookie domain will be .google.com
const getCookieDomain = ctx => domain((ctx.origin && new URL(ctx.origin).hostname) || ctx.hostname)

Growthbook middleware

It is responsible for acquiring the growthbook instance, loading the features and setting the instance in the ctx.state.growthbook to be used by other middlewares.

Example route configuration

const { middlewares: { growthbook } } = require('@workablehr/orka');

module.exports = {
  get: {
    '/endpoint': async (ctx, next) => {
      ctx.body = ctx.state.growthbook.isOn('featureA') ? 'ON' : 'OFF';
    }
  },
  prefix: {
    '/': growthbook
  }
};

If you need to set attributes you can do by accessing the ctx.state.growthbook to another endpoint and using the setAttributes method of growthbook instance.