Domain Configuration
Authorize and map domains in mod_pagespeed 1.1. Domain authorization, MapOriginDomain, MapRewriteDomain, ShardDomain for nginx, Apache, IIS, and Envoy.
mod_pagespeed rewrites and optimizes resources referenced by HTML pages. To do this safely, it must know which domains it is allowed to fetch from and how domain names map between the public-facing URL and the actual origin.
Domain authorization
mod_pagespeed only fetches and optimizes resources from authorized domains. By default, the domain that serves the HTML page is authorized automatically. Resources hosted on any other domain are left untouched unless that domain is explicitly authorized.
pagespeed Domain cdn.example.com;
pagespeed Domain *.example.com;ModPagespeedDomain cdn.example.com
ModPagespeedDomain *.example.compagespeed Domain cdn.example.com
pagespeed Domain *.example.comWildcards are supported. A wildcard entry like *.example.com authorizes all subdomains under example.com. Without authorization, mod_pagespeed ignores resources from unlisted domains entirely — it does not fetch, rewrite, or cache them.
MapOriginDomain
Maps a public-facing domain to a different origin server for fetching. Use this when mod_pagespeed sits behind a load balancer, CDN, or reverse proxy and the public hostname does not resolve to the machine running mod_pagespeed.
pagespeed MapOriginDomain localhost www.example.com;ModPagespeedMapOriginDomain localhost www.example.compagespeed MapOriginDomain localhost www.example.comThis directive tells mod_pagespeed to fetch resources for www.example.com from localhost instead. The rewritten URLs in the HTML still reference www.example.com — only the fetch target changes. This implicitly authorizes the origin domain.
MapRewriteDomain
Rewrites resource URLs in the HTML output to use a different domain. Use this to serve optimized resources from a CDN or a cookie-free domain.
pagespeed MapRewriteDomain cdn.example.com www.example.com;ModPagespeedMapRewriteDomain cdn.example.com www.example.compagespeed MapRewriteDomain cdn.example.com www.example.comResources originally referenced on www.example.com will have their URLs rewritten to cdn.example.com in the HTML output. The target domain (cdn.example.com) must serve the same optimized resources — typically by proxying back to the mod_pagespeed server or by using MapOriginDomain on the CDN’s origin.
ShardDomain
Distributes optimized resource URLs across multiple domains. Browsers enforce a per-domain connection limit under HTTP/1.1, so spreading resources across shards increases parallel downloads. This technique is less relevant with HTTP/2, which multiplexes requests over a single connection.
pagespeed ShardDomain www.example.com shard1.example.com,shard2.example.com;ModPagespeedShardDomain www.example.com shard1.example.com,shard2.example.compagespeed ShardDomain www.example.com shard1.example.com,shard2.example.comAll shard domains must be authorized (explicitly or via MapOriginDomain) and must serve the same content as the primary domain. mod_pagespeed assigns resources to shards deterministically based on the resource URL, so a given resource always maps to the same shard.
MapProxyDomain
Proxies and optimizes content from an entirely separate origin through the mod_pagespeed server. This effectively creates a reverse proxy for the mapped domain.
pagespeed MapProxyDomain www.example.com/external https://other-site.example.com;ModPagespeedMapProxyDomain www.example.com/external https://other-site.example.compagespeed MapProxyDomain www.example.com/external https://other-site.example.comRequests to www.example.com/external/ are fetched from https://other-site.example.com/, optimized, and served through the local server. Use this directive with caution — it exposes the mod_pagespeed server as a proxy for external content.
LoadFromFile
Loads resources directly from the local filesystem instead of fetching them over HTTP. This eliminates fetch latency and HTTP overhead for resources that are stored on the same machine.
pagespeed LoadFromFile "http://www.example.com/static/" "/var/www/static/";ModPagespeedLoadFromFile "http://www.example.com/static/" "/var/www/static/"pagespeed LoadFromFile "http://www.example.com/static/" "C:\inetpub\wwwroot\static\"Windows-style backslash paths are converted to forward slashes internally.
The first argument is the URL prefix. The second is the filesystem path that corresponds to it. Resources loaded from files bypass the HTTP cache entirely. mod_pagespeed watches the filesystem for changes and re-optimizes when files are modified.
See also
- Configuration — general configuration reference
- Caching — how domain configuration affects caching behavior