Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

Custom domain name for REST APIs in API Gateway

Custom domain names are simpler and more intuitive URLs that you can provide to your API users.

After deploying your API, you (and your customers) can invoke the API using the default base URL of the following format:

https://api-id.execute-api.region.amazonaws.com/stage

where api-id is generated by API Gateway, region is the Amazon Region, and stage is specified by you when deploying the API.

The hostname portion of the URL, api-id.execute-api.region.amazonaws.com refers to an API endpoint. The default API endpoint name is randomly generated, difficult to recall, and not user-friendly.

With custom domain names, you can set up your API's hostname, and choose a base path (for example, myservice) to map the alternative URL to your API. For example, a more user-friendly API base URL can become:

https://api.example.com/myservice

Considerations

The following considerations might impact your use of a custom domain name.

Prerequisites

The following are prerequisites for creating a custom domain name.

Register a domain name

You must have a registered internet domain name in order to set up custom domain names for your APIs. You can register your internet domain name using Amazon Route 53 or using a third-party domain registrar of your choice. Your custom domain name can be the name of a subdomain or the root domain (also known as the "zone apex") of a registered internet domain.

Your domain name must follow the RFC 1035 specification and can have a maximum of 63 octets per label and 255 octets in total.

Specify the certificate for your custom domain name

Before setting up a custom domain name for an API, you must have an SSL/TLS certificate ready in ACM. If ACM is not available in the Amazon Region where you are creating your custom domain name, you must import a certificate to API Gateway in that Region.

To import an SSL/TLS certificate, you must provide the PEM-formatted SSL/TLS certificate body, its private key, and the certificate chain for the custom domain name.

Each certificate stored in ACM is identified by its ARN. With certificates issued by ACM, you do not have to worry about exposing any sensitive certificate details, such as the private key. To use an Amazon managed certificate for a domain name, you simply reference its ARN.

If your application uses certificate pinning, sometimes known as SSL pinning, to pin an ACM certificate, the application might not be able to connect to your domain after Amazon renews the certificate. For more information, see Certificate pinning problems in the Amazon Certificate Manager User Guide.

Wildcard custom domain names

With wildcard custom domain names, you can support an almost infinite number of domain names without exceeding the default quota. For example, you could give each of your customers their own domain name, customername.api.example.com.

To create a wildcard custom domain name, specify a wildcard (*) as the first subdomain of a custom domain that represents all possible subdomains of a root domain.

For example, the wildcard custom domain name *.example.com results in subdomains such as a.example.com, b.example.com, and c.example.com, which all route to the same domain.

Wildcard custom domain names support distinct configurations from API Gateway's standard custom domain names. For example, in a single Amazon account, you can configure *.example.com and a.example.com to behave differently.

You can use the $context.domainName and $context.domainPrefix context variables to determine the domain name that a client used to call your API. To learn more about context variables, see API Gateway mapping template and access logging variable reference.

To create a wildcard custom domain name, you must provide a certificate issued by ACM that has been validated using either the DNS or the email validation method.

Next steps for custom domain names

The following are next steps for custom domain names:

If this is your first time creating a custom domain name, we recommend that you start with Get certificates ready in Amazon Certificate Manager, to specify your certificate, and then Set up a Regional custom domain name in API Gateway to create a Regional custom domain name.