Server-side Rendering, aka SSR, can be enabled in Astro. When you enable SSR you can:
- Implement sessions for login state in your app.
- Render data from an API called dynamically with
- Deploy your site to a host using an adapter.
Enabling SSR in Your ProjectSection titled Enabling SSR in Your Project
To get started, enable SSR features in development mode with the
output: server configuration option:
Adding an AdapterSection titled Adding an Adapter
When it’s time to deploy an SSR project, you also need to add an adapter. This is because SSR requires a server runtime: the environment that runs your server-side code. Each adapter allows Astro to output a script that runs your project on a specific runtime.
The following adapters are available today with more to come in the future:
Section titled astro add Install
astro add Install
You can add any of the official adapters with the following
astro add command. This will install the adapter and make the appropriate changes to your
astro.config.mjs file in one step. For example, to install the Netlify adapter, run:
Manual InstallSection titled Manual Install
You can also add an adapter manually by installing the package and updating
astro.config.mjs yourself. (See the links above for adapter-specific instructions to complete the following two steps to enable SSR.) Using
my-adapter as an example placeholder, the instructions will look something like:
Install the adapter to your project dependencies using your preferred package manager:
Add the adapter to your
astro.config.mjsfile’s import and default export:
FeaturesSection titled Features
Astro will remain a static-site generator by default. But once you enable a server-side rendering adapter, every route in your pages directory defaults to a server-rendered route and a few new features become available to you.
Hybrid RenderingSection titled Hybrid Rendering
To enable hybrid rendering, any page or server endpoint that supports exporting variables (
.js) can opt-in to prerendering. These files will be statically rendered at build-time, similar to the default static
export const prerender = true:
Section titled Astro.request.headers
The headers for the request are available on
Astro.request.headers. It is a Headers object, a Map-like object where you can retrieve headers such as the cookie.
Section titled Astro.cookies
This is a utility to read and modify a single cookie. It allows you to check, set, get and delete a cookie.
See more details about
Astro.cookies and the
AstroCookie type in the API reference.
The example below updates the value of a cookie for a page view counter.
Section titled Astro.redirect
Astro global, this method allows you to redirect to another page. You might do this after checking if the user is logged in by getting their session from a cookie.
Section titled Response
You can also return a Response from any page. You might do this to return a 404 on a dynamic page after looking up an id in the database.
Server EndpointsSection titled Server Endpoints
A server endpoint, also known as an API route, is a
.ts file within the
src/pages folder that takes a Request and returns a Response. A powerful feature of SSR, API routes are able to securely execute code on the server side. To learn more, see our Endpoints Guide.