Replace servers URL in different environments

Redocly allows you to use custom decorators to modify content in the API description during the bundling process.

You can use this method to create multiple instances of an API description file from a single source, each with a different server. For example, you can have separate API descriptions configured with your mock server and your production server, or separate API files for each of your customers.

This page describes how to replace the server URL with a decorator for a given environment.

Prerequisites

• Install @redocly/cli. We use version 1.12.0 in this tutorial.

• Install @redocly/cli with version 1.0.0-beta.111 or later (we use 1.0.0-beta.111 in this tutorial).

• Save the following OpenAPI file as original.yaml into a new directory named replace-servers-demo.

  openapi: 3.1.0
  info:
    version: 1.0.0
    title: Custom decorators demo
    description: The servers URL is replaced by the decorator during the `bundle` process.
  servers:
    - url: 'https://example.com/api/v1'
  paths:
    /status:
      get:
        summary: Get status
        operationId: getStatus
        security: []
        responses:
          '204':
            description: Status OK
          '400':
            description: Status not OK
  

• Use your favorite IDE for editing files (we use VS Code and have the Redocly extension installed).

Create a demo folder and description file

Before you start, create a demo folder and a sample OpenAPI description file to later test your plugin and decorators.

1. Create a new folder and name it replace-servers-demo.

2. In the replace-servers-demo folder, create an original.yaml file with the following content:

openapi: 3.1.0
    info:
      version: 1.0.0
      title: Custom decorators demo
      description: The servers URL is replaced by the decorator during the `bundle` process.
servers:
  - url: 'https://example.com/api/v1'
paths:
  /status:
    get:
      summary: Get status
      operationId: getStatus
      security: []
      responses:
        '204':
          description: Status OK
        '400':
          description: Status not OK

3. Save the file.

Create a custom plugin

In this step, create a custom plugin and define the decorator dependency.

1. In the replace-servers-demo folder, create a folder called plugins.

2. In the plugins folder, create a plugin.js file with this code:

const ReplaceServersURL = require('./decorators/replace-servers-url');
const id = 'plugin';

/** @type {import('@redocly/cli').DecoratorsConfig} */
const decorators = {
  oas3: {
    'replace-servers-url': ReplaceServersURL,
  },
};

module.exports = function replaceServersUrlPlugin() {
  return {
    id,
    decorators,
  };
};

3. Save the file.

Add a decorator and associate it with an environment variable

In this step, add a decorator and define the environment variable associated with it.

1. Inside the plugins folder, create a decorators folder.

2. In the decorators folder, create a replace-servers-url.js file with this code:

module.exports = ReplaceServersURL;

/** @type {import('@redocly/cli').OasDecorator} */

function ReplaceServersURL({serverUrl}) {
  return {
    Server: {
      leave(Server) {

        if (serverUrl) {
          Server.url = serverUrl;
        }

      }
    }
  }
};

3. Save the file.

Configure the plugin for use

To use the decorators, register your plugins and decorators in the Redocly configuration file.

• In your Redocly configuration file, register your plugins and decorators:

apis:
  sample@v1-backend:
    root: original.yaml
    decorators:
      plugin/replace-servers-url:
        serverUrl: 'https://backend.example.com/v1'
  sample@v1-proxy:
    root: original.yaml
    decorators:
      plugin/replace-servers-url:
        serverUrl: 'https://proxy.example.com/v1'
plugins:
  - './plugins/plugin.js'
extends:
  - recommended

Verify the output

Check the configuration for the "backend" server

1. Run the following command to bundle the original.yaml API with the "backend" server URL.

npx @redocly/cli bundle sample@v1-backend

2. Verify that the output shows the correct server URL.

openapi: 3.1.0
info:
  version: 1.0.0
  title: Custom decorators demo
  description: The servers URL is replaced by the decorator during the `bundle` process.
servers:
  - url: https://backend.example.com/v1
# ...

Check the configuration for the "proxy" server

1. Run the following command bundles the original.yaml API with the "proxy" server URL.

npx @redocly/cli bundle sample@v1-proxy

2. Verify that the output shows the correct server URL.

openapi: 3.1.0
info:
  version: 1.0.0
  title: Custom decorators demo
  description: The servers URL is replaced by the decorator during the `bundle` process.
servers:
  - url: https://proxy.example.com/v1
# ...

Summary

In this tutorial you have created a plugin and a decorator that replace the server URL with one of the URLs defined in the Redocly configuration file.

You now have two API description files, each configured to send requests to different servers.

What's next?

You can reuse the code from your demo files and modify it to fit your API documentation.

For more custom plugins, configuration, and other resources, see the Redocly CLI Cookbook.

For the latest Redocly news and articles, visit our blog.