Configure virtual hosts

Contents

Overview
Configure virtual hosts for HTTP services

Overview

A virtual host is a server, or pool of servers, that can host multiple domain names (for example, company1.api.example.com and company2.api.example.com). This enables you to run more than one website, or set of REST APIs, on a single host machine (for example, 192.0.2.11). Each domain name can have its own hostname, paths, APIs, and so on. For example: 

https://company1.api.example.com:8080/api/v1/test
https://company2.api.example.com:8080/api/v2/test
https://company3.api.example.com:8080/api/v2/test

The API Gateway implements name-based virtual hosting, in which the client HTTP Host header is used as the routing criteria during path resolution (for example, Host company1.api.example.com). This means that you can have multiple domains running on the same hardware (IP address), while this is not apparent to the client or end user.

For example, the following URL invokes the company2.api.example.com virtual host: 

https:/company2.api.example.com/api/v1/test

This results in the following message at runtime: 

POST /api/v1/test HTTP/1.1
Host: company2.api.example.com
Content-Type: application/x-www-form-urlencoded

client_id=SampleConfidentialApp&client_secret=......

[Important] Important

To support name-based virtual hosts, you must first ensure that your Domain Name System (DNS) server has been updated to map each hostname to the correct IP address (for example, *.example.com is mapped to 192.0.2.11). For more details, see the topic on "Configuring a DNS service with wildcards for virtual hosting" in the API Gateway Administrator Guide.

When your DNS server has been updated to map each hostname to the correct IP address, you can then configure the API Gateway for virtual hosting.

Configure virtual hosts for HTTP services

Configure child resolvers

You can configure virtual hosts at the HTTP service level. This means that these settings are applied to the HTTP service and to any child resolvers. To configure a virtual host at the HTTP service level, perform the following steps:

  1. In the Policy Studio tree, select an HTTP service (for example, Listeners > API Gateway > Default Services > Virtual Hosts).

  2. Right-click, and select Add a Virtual Host.

  3. Configure the following settings in the Virtual Host dialog:

    • Name:

      Enter a unique name of the virtual host.

    • Enabled:

      Select whether the virtual host processing is enabled. This is enabled by default.

    • Hosts:

      Specify the list of domains that you wish to host under this HTTP service. To add a host, click Add at the bottom right, and enter the domain name (for example company1.api.example.com).

      You can also specify domain names using wildcards already configured in your DNS (for example *.example.com:/8080 or company3.api.example.com.*). For details on configuring DNS wildcards, see the API Gateway Administrator Guide.

Configure child resolvers

When you have configured a virtual host at the HTTP service level, you can also configure the following child resolvers:

  • Relative path

  • Static content provider

  • Static file provider

  • Servlet application

To configure a child resolver, perform the following steps:

  1. In the Policy Studio tree, select the Paths node under the virtual host, and right-click to add a resolver (for example, Add relative path).

  2. In the Resolve path to policies dialog, click the browse button beside the Path Specific Policy field, and select a policy to run on this path.

For example, if an inbound request to /Healthcheck matches on company1.api.*, the Company1 Health Check policy is executed. Otherwise, the global Health Check policy for the HTTP service is executed (in this case, Default Services).

Configuring a Virtual Host Resolver

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