Request Headers

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.

Request headers

An incoming HTTP request includes the HTTP headers sent by the client. For security purposes, some headers are sanitized or amended by intermediate proxies before they reach the application.

Removed headers

Headers that match the following pattern are removed from the request:

  • X-Google-*

In addition, some selected headers that match the following pattern are removed from the request:

  • X-Appengine-*

App Engine-specific headers

As a service to the app, App Engine adds the following headers to all requests:

Via: "1.1 google"

X-AppEngine-Country

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-Country header. Your application should handle the special country code ZZ (unknown country).

X-AppEngine-Region

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.

X-AppEngine-City

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.

X-AppEngine-CityLatLong

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.

X-Cloud-Trace-Context

A unique identifier for the request used for Stackdriver Trace and Stackdriver 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]

Shows http or https based on the protocol the client used to connect to your application.

The Google Cloud Load Balancer terminates all https connections, and then forwards traffic to App Engine instances over http. For example, if a user requests access to your site via https://[MY-PROJECT-ID].appspot.com, the X- Forwarded-Proto header value is https.

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