This article is for developers who want to host server-side tagging in the same first-party context as their website. Same-origin serving is a best practice that lets you leverage the security and durability benefits of server-set cookies. The below instructions apply for setting up same-origin serving regardless of the Google tag deployed on your site (gtag.js or gtm.js).
When you first set up a tagging server, it is hosted on a domain provided by the cloud provider. When you use the default endpoint, it delivers data to the server container, but runs in a third-party context. To unlock the benefits of a first-party context, such as more durable cookies, your tagging server and your website have to run on the same domain.
The table below illustrates how you can host a tagging server when the parent
website is hosted on www.example.com:
| Same origin (best practice) | Subdomain | Default domain | |
|---|---|---|---|
| Example URL | https://www.example.com/metrics |
https://metrics.example.com |
https://metrics.run.app |
| Server-set cookie access | Full access to security and durability benefits. | Full access to security and durability benefits. | None. Can only set Javascript cookies. |
| Setup complexity | Configure a CDN or load balancer to forward requests. May need to update DNS entries. | Update DNS entries. | Comes pre-configured. |
Pick your implementation option to get started.
Prerequisites
This guide assumes that you have:
- Set up a server container in Tag Manager
- Set up a tagging server