REGION_ID is an abbreviated code that Google assigns
based on the region you select when you create your app. The code does not
correspond to a country or province, even though some region IDs may appear
similar to commonly used country and province codes. Including
REGION_ID.r in App Engine URLs is optional for
existing apps and will soon be required for all new apps.
To ensure a smooth transition, we are slowly updating App Engine to use region IDs. If we haven't updated your Google Cloud project yet, you won't see a region ID for your app. Since the ID is optional for existing apps, you don't need to update URLs or make other changes once the region ID is available for your existing apps.
Learn more about region IDs.
Use this reference page for details about what HTTP headers are supported . To understand how App Engine receives requests and sends responses, see How Requests Are Handled.
An incoming HTTP request includes the HTTP headers sent by the client. For security purposes, some headers are sanitized, amended, or removed by intermediate proxies before they reach the application.
Headers removed from incoming requests
The following headers are removed from incoming requests if a client sends them:
Headers with names that match the
X-Google-*pattern. This name pattern is reserved for Google.
Headers with names that match App Engine-specific headers. Only exact, case-insensitive matches are removed. For example, headers named
X-AppEngine-Countrywill be removed but
App Engine-specific headers
As a service to the app, App Engine adds the following headers to all requests:
- Country from which the request originated, as an ISO 3166-1
alpha-2 country code.
App Engine determines this code from the client's IP address. Note that
the country information is not derived from the WHOIS database; it's possible
that an IP address with country information in the WHOIS database will not have
country information in the
X-Appengine-Countryheader. Your application should handle the special country code
- Name of region from which the request originated. This value only makes
sense in the context of the country in
X -Appengine-Country. For example, if the country is "US" and the region is "ca", that "ca" means "California", not Canada. The complete list of valid region values is found in the ISO-3166-2 standard.
- Name of the city from which the request originated. For example, a request
from the city of Mountain View might have the header value
mountain view. There is no canonical list of valid values for this header.
- Latitude and longitude of the city from which the request originated. This string might look like "37.386051,-122.083851" for a request from Mountain View.
- A unique identifier for the request used for Cloud Trace and Cloud Logging.
X-Forwarded-For: [CLIENT_IP(s)], [global forwarding rule IP]
A comma-delimited list of IP addresses through which the client request has been routed. The first IP in this list is generally the IP of the client that created the request. The subsequent IPs provide information about proxy servers that also handled the request before it reached the application server. For example:
X-Forwarded-For: clientIp, proxy1Ip, proxy2Ip
X-Forwarded-Proto [http | https]
httpsbased on the protocol the client used to connect to your application.
The Google Cloud Load Balancer terminates all
httpsconnections, and then forwards traffic to App Engine instances over
http. For example, if a user requests access to your site via
https://PROJECT_ID.REGION_ID.r.appspot.com, the X- Forwarded-Proto header value is
In addition, App Engine may set the following headers which are for internal use by App Engine: