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Gcore CDN edge servers support HTTP/2 and enable it by default. When a client browser supports HTTP/2 and the CDN resource uses HTTPS, the CDN can deliver content over HTTP/2. Browsers use HTTP/2 only over HTTPS. Add an SSL certificate to the CDN resource to secure the client-to-CDN connection. Gcore CDN uses HTTP/1.1 for origin requests and does not connect to origins over HTTP/2 or cleartext h2c. Enabling HTTP/2 on the origin therefore does not improve the CDN-to-origin connection; it benefits clients and other services that connect directly to the origin with HTTP/2. For direct HTTP/2 over TLS, the origin needs its own HTTPS configuration, certificate, and ALPN-capable TLS stack. The CDN resource certificate covers only the client-to-CDN connection and does not configure HTTPS or ALPN on the origin.

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Nginx configuration

Nginx 1.9.5 or later with the HTTP/2 module is required.
  1. Open the HTTPS server block in the Nginx configuration (often /etc/nginx/nginx.conf or a file under /etc/nginx/sites-available/).
  2. Enable HTTP/2 with the syntax for the installed version. For Nginx 1.25.1 and later, use:
    For Nginx 1.9.5 through 1.25.0, use:
    For cleartext h2c on Nginx 1.25.1 and later, use:
    For cleartext h2c on Nginx 1.9.5 through 1.25.0, use:
    Nginx does not negotiate h2c through an HTTP/1.1 Upgrade request, so clients must start HTTP/2 with prior knowledge. In versions before 1.25.1, an h2c socket accepts only HTTP/2; assign a dedicated port if HTTP/1.x clients must remain supported. Starting with version 1.25.1, the socket detects the HTTP/2 connection preface and otherwise uses HTTP/1.x.
  3. Test and reload Nginx:

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Apache configuration

Apache 2.4.17 or later is required. HTTP/2 over TLS also requires an ALPN-capable TLS library.
  1. Enable the mod_http2 module (also known as mod_h2).
  2. Add the matching Protocols line to the virtual host configuration:
  3. Check the configuration:
  4. If the check returns Syntax OK, reload or restart Apache with the command for the operating system. On systems that use the apache2 systemd service, run:

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Origin verification

Test the origin directly after enabling HTTP/2. For HTTP/2 over TLS, run:
Confirm that the first response status line starts with HTTP/2. This test uses the origin hostname and certificate, not the CDN custom domain or CDN resource certificate. If the origin supports cleartext h2c, test it separately:
Confirm that the first response status line starts with HTTP/2.

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Benefits for direct origin connections

These benefits apply only to clients or services that connect directly to the origin over HTTP/2, not to Gcore CDN origin requests. A direct client can reuse a single TCP connection for many requests, which reduces connection overhead compared with opening parallel HTTP/1.1 connections and avoids splitting assets across hostnames to raise connection limits.