Configuring the Caddy Web Server

The API Platform distribution is shipped with the Caddy web server. The build contains the Mercure and the Vulcain Caddy modules.

Caddy is positioned in front of the web API and of the Progressive Web App. It routes requests to either service depending on the value of the Accept HTTP header or the extension of the requested file.

Using the same domain to serve the API and the PWA improves performance by preventing unnecessary CORS preflight requests and encourages embracing the REST principles.

By default, requests having an Accept request header containing the text/html media type are routed to the Next.js application, except for some paths known to be resources served by the API (e.g. the Swagger UI documentation, static files provided by bundles…). Other requests are routed to the API.

Sometimes, you may want to let the PHP application generate HTML responses. For instance, when you create your own Symfony controllers serving HTML pages, or when using bundles such as EasyAdmin or SonataAdmin.

To do so, you have to tweak the rules used to route the requests. Open api-platform/api/docker/caddy/Caddyfile and modify the expression. You can use any CEL (Common Expression Language) expression supported by Caddy.

For instance, if you want to route all requests to a path starting with /admin to the API, modify the existing expression like this:

# Matches requests for HTML documents, for static files and for Next.js files,
# except for known API paths and paths with extensions handled by API Platform
@pwa expression `(
        {header.Accept}.matches("\\btext/html\\b")
        && !{path}.matches("(?i)(?:^/docs|^/graphql|^/bundles/|^/_profiler|^/_wdt|\\.(?:json|html$|csv$|ya?ml$|xml$))")
        && !{path}.matches("(?i)(?:^/admin|^/docs|^/graphql|^/bundles/|^/_profiler|^/_wdt|\\.(?:json|html$|csv$|ya?ml$|xml$))")
    )`