docs: extract how-to guides from "Server" page

docs/site/Server.md

@@ -17,6 +17,11 @@ for requests on a specific port, handle them, and return appropriate responses.
 A single application can have multiple server instances listening on different
 ports and working with different protocols.
 
+## Common tasks
+
+- [Enable HTTPS](./guides/deployment/enabling-https.md)
+- [Customize how OpenAPI spec is served](./guides/rest/customize-openapi.md)
+
 ## Usage
 
 LoopBack 4 offers the
@@ -69,40 +74,6 @@ const app = new RestApplication({
 });
 ```
 
-### Customize How OpenAPI Spec is Served
-
-There are a few options under `rest.openApiSpec` to configure how OpenAPI spec
-is served by the given REST server.
-
-- servers: Configure servers for OpenAPI spec
-- setServersFromRequest: Set `servers` based on HTTP request headers, default to
-  `false`
-- disabled: Set to `true` to disable endpoints for the OpenAPI spec. It will
-  disable API Explorer too.
-- endpointMapping: Maps urls for various forms of the spec. Default to:
-
-```js
-    {
-      '/openapi.json': {version: '3.0.0', format: 'json'},
-      '/openapi.yaml': {version: '3.0.0', format: 'yaml'},
-    }
-```
-
-```ts
-const app = new RestApplication({
-  rest: {
-    openApiSpec: {
-      servers: [{url: 'http://127.0.0.1:8080'}],
-      setServersFromRequest: false,
-      endpointMapping: {
-        '/openapi.json': {version: '3.0.0', format: 'json'},
-        '/openapi.yaml': {version: '3.0.0', format: 'yaml'},
-      },
-    },
-  },
-});
-```
-
 ### Configure the API Explorer
 
 LoopBack allows externally hosted API Explorer UI to render the OpenAPI
@@ -153,37 +124,6 @@ Explorer UI. Please refer to
 [Self-hosted REST API Explorer](./Self-hosted-REST-API-Explorer.md) for more
 details.
 
-### Enable HTTPS
-
-Enabling HTTPS for the LoopBack REST server is just a matter of specifying the
-protocol as `https` and specifying the credentials.
-
-In the following app, we configure HTTPS for a bare minimum app using a key +
-certificate chain variant.
-
-```ts
-import {RestApplication, RestServer, RestBindings} from '@loopback/rest';
-import fs from 'fs';
-
-export async function main() {
-  const options = {
-    rest: {
-      protocol: 'https',
-      key: fs.readFileSync('./key.pem'),
-      cert: fs.readFileSync('./cert.pem'),
-    },
-  };
-  const app = new RestApplication(options);
-  app.handler(handler => {
-    handler.response.send('Hello');
-  });
-  await app.start();
-
-  const url = app.restServer.url;
-  console.log(`Server is running at ${url}`);
-}
-```
-
 ### Customize CORS
 
 [CORS](https://en.wikipedia.org/wiki/Cross-origin_resource_sharing) is enabled

docs/site/guides/deployment/enabling-https.md

@@ -0,0 +1,67 @@
+---
+lang: en
+title: 'Enabling HTTPS'
+keywords: LoopBack 4.0, LoopBack 4, Node.js, HTTPS, Deployment
+sidebar: lb4_sidebar
+permalink: /doc/en/lb4/Enabling-https.html
+---
+
+Enabling HTTPS for the LoopBack REST server is just a matter of updating the
+`rest` section of application configuration:
+
+1. Specify the protocol as `https`.
+2. Provide TLS server credentials.
+
+Example:
+
+```ts
+const config = {
+  rest: {
+    protocol: 'https',
+    key: fs.readFileSync('./key.pem'),
+    cert: fs.readFileSync('./cert.pem'),
+    // port, host, etc.
+  },
+};
+```
+
+See
+[Node.js documentation](https://nodejs.org/api/https.html#https_https_createserver_options_requestlistener)
+for supported forms of HTTPS/TLS credentials, in particular
+[`tls.createSecureContext()` options](https://nodejs.org/api/tls.html#tls_tls_createsecurecontext_options).
+
+In the following app, we configure HTTPS for a bare minimum app using a key +
+certificate chain variant.
+
+{% include code-caption.html content="/src/index.ts" %}
+
+```ts
+import {ApplicationConfig, TodoListApplication} from './application';
+
+export async function main(options: ApplicationConfig = {}) {
+  // left out for brevity
+}
+
+if (require.main === module) {
+  // Run the application
+  const config = {
+    rest: {
+      port: +(process.env.PORT ?? 3000),
+      host: process.env.HOST ?? 'localhost',
+      openApiSpec: {
+        // useful when used with OpenAPI-to-GraphQL to locate your application
+        setServersFromRequest: true,
+      },
+
+      // Enable HTTPS
+      protocol: 'https',
+      key: fs.readFileSync('./key.pem'),
+      cert: fs.readFileSync('./cert.pem'),
+    },
+  };
+  main(config).catch(err => {
+    console.error('Cannot start the application.', err);
+    process.exit(1);
+  });
+}
+```

docs/site/guides/rest/customize-openapi.md

@@ -0,0 +1,48 @@
+---
+lang: en
+title: 'Customizing how OpenAPI spec is served'
+keywords: LoopBack 4.0, LoopBack 4, Node.js, OpenAPI, Customization
+sidebar: lb4_sidebar
+permalink: /doc/en/lb4/Customizing-how-openapi-spec-is-served.html
+---
+
+By default, LoopBack REST API server provides endpoints exposing an OpenAPI spec
+document describing application's API. You can configure this behavior using
+`rest.openApiSpec` field in the configuration object passed to `RestApplication`
+constructor.
+
+- servers: Configure servers for OpenAPI spec
+
+- setServersFromRequest: Set `servers` based on HTTP request headers, default to
+  `false`
+
+- disabled: Set to `true` to disable endpoints for the OpenAPI spec. It will
+  disable API Explorer too.
+
+- endpointMapping: Maps urls for various forms of the spec. Default to:
+
+  ```js
+  {
+    '/openapi.json': {version: '3.0.0', format: 'json'},
+    '/openapi.yaml': {version: '3.0.0', format: 'yaml'},
+  }
+  ```
+
+Example application configuration object showing possible customizations:
+
+{% include code-caption.html content="/src/index.ts" %}
+
+```ts
+const config: ApplicationConfig = {
+    rest: {
+    openApiSpec: {
+      servers: [{url: 'http://127.0.0.1:8080'}],
+      setServersFromRequest: false,
+      endpointMapping: {
+        '/openapi.json': {version: '3.0.0', format: 'json'},
+        '/openapi.yaml': {version: '3.0.0', format: 'yaml'},
+      },
+    },
+  };
+});
+```

docs/site/sidebars/lb4_sidebar.yml

@@ -181,6 +181,13 @@ children:
   output: 'web, pdf'
   children:
 
+  - title: 'Building REST APIs'
+    output: 'web, pdf'
+    children:
+    - title: 'Customizing how OpenAPI spec is served'
+      url: Customizing-how-openapi-spec-is-served.html
+      output: 'web, pdf'
+
   - title: 'Create Other Forms of APIs'
     url: Create-other-forms-of-apis.html
     output: 'web, pdf'
@@ -305,6 +312,10 @@ children:
     url: Deployment.html
     output: 'web, pdf'
     children:
+      - title: 'Enabling HTTPS'
+        url: 'Enabling-https.html'
+        output: 'web, pdf'
+
       - title: 'Deploying to IBM Cloud'
         url: Deploying-to-IBM-Cloud.html
         output: 'web, pdf'