Request Headers in Cloud Functions

Note: Cloud Functions (2nd gen) is now Cloud Run functions. The information on this page applies to using the Cloud Functions API, which is still supported for performing operations on functions.

An incoming HTTP request includes the HTTP headers sent by the client. Use this reference page for details about how these HTTP headers are processed in Cloud Functions requests.

Headers removed from incoming requests

For security purposes, some headers are sanitized or amended by intermediate proxies before they reach your function.

Headers with names that match the X-Google-* pattern are removed from incoming requests if a client sends them. This name pattern is reserved for use by Google.

In addition, the following headers are removed from incoming requests because they relate to the transfer of HTTP data between the client and server:

• Connection
• Keep-Alive
• Proxy-Authorization
• TE
• Trailer
• Transfer-Encoding

Note: Entity headers (headers relating to the request body) are not sanitized or checked, so functions should not rely on them. In particular, the Content-MD5 request header is sent unmodified to the function, so it might not match the MD5 hash of the content. Also, the Content-Encoding request header is not checked by the server, so if the client sends a gzipped request body, it will be sent in compressed form to the application.

Headers added for your use

Cloud Functions adds the following headers to all requests:

X-Cloud-Trace-Context

A unique identifier for the request used for Cloud Trace and Cloud Logging. For example: "65011637f09e0a5179677a7429456db7/1027871334010811884;o=1"

X-Forwarded-For

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

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 Cloud Functions over http. For example, if the request is sent to:

https://YOUR_PROJECT_ID.cloudfunctions.net/YOUR_FUNCTION_NAME

the X-Forwarded-Proto header value is https.