Type of session affinity to use. The default is NONE. Only NONE and
HEADER_FIELD are supported when the backend service is referenced by
a URL map that is bound to target gRPC proxy that has
validateForProxyless field set to true. For more details, see:
Session
Affinity <https://cloud.google.com/load-balancing/docs/backend-service#session_affinity>__.
sessionAffinity cannot be specified with haPolicy.
Enums
Name
Description
UNDEFINED_SESSION_AFFINITY
A value indicating that the enum field is not set.
CLIENT_IP
2-tuple hash on packet's source and destination IP addresses. Connections from the same source IP address to the same destination IP address will be served by the same backend VM while that VM remains healthy.
CLIENT_IP_NO_DESTINATION
1-tuple hash only on packet's source IP address. Connections from the same source IP address will be served by the same backend VM while that VM remains healthy. This option can only be used for Internal TCP/UDP Load Balancing.
CLIENT_IP_PORT_PROTO
5-tuple hash on packet's source and destination IP addresses, IP protocol, and source and destination ports. Connections for the same IP protocol from the same source IP address and port to the same destination IP address and port will be served by the same backend VM while that VM remains healthy. This option cannot be used for HTTP(S) load balancing.
CLIENT_IP_PROTO
3-tuple hash on packet's source and destination IP addresses, and IP protocol. Connections for the same IP protocol from the same source IP address to the same destination IP address will be served by the same backend VM while that VM remains healthy. This option cannot be used for HTTP(S) load balancing.
GENERATED_COOKIE
Hash based on a cookie generated by the L7 loadbalancer. Only valid for HTTP(S) load balancing.
HEADER_FIELD
The hash is based on a user specified header field.
HTTP_COOKIE
The hash is based on a user provided cookie.
NONE
No session affinity. Connections from the same client IP may go to any instance in the pool.
STRONG_COOKIE_AFFINITY
Strong cookie-based affinity. Connections bearing the same cookie will be served by the same backend VM while that VM remains healthy, as long as the cookie has not expired.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-11 UTC."],[],[],null,["# Class SessionAffinity (1.35.0)\n\nVersion latestkeyboard_arrow_down\n\n- [1.35.0 (latest)](/python/docs/reference/compute/latest/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.34.0](/python/docs/reference/compute/1.34.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.33.0](/python/docs/reference/compute/1.33.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.32.0](/python/docs/reference/compute/1.32.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.31.0](/python/docs/reference/compute/1.31.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.30.0](/python/docs/reference/compute/1.30.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.29.0](/python/docs/reference/compute/1.29.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.28.0](/python/docs/reference/compute/1.28.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.27.0](/python/docs/reference/compute/1.27.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.26.0](/python/docs/reference/compute/1.26.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.25.0](/python/docs/reference/compute/1.25.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.24.0](/python/docs/reference/compute/1.24.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.23.0](/python/docs/reference/compute/1.23.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.22.0](/python/docs/reference/compute/1.22.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.21.0](/python/docs/reference/compute/1.21.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.20.1](/python/docs/reference/compute/1.20.1/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.19.2](/python/docs/reference/compute/1.19.2/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.18.0](/python/docs/reference/compute/1.18.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.17.0](/python/docs/reference/compute/1.17.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.16.1](/python/docs/reference/compute/1.16.1/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.15.0](/python/docs/reference/compute/1.15.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.14.1](/python/docs/reference/compute/1.14.1/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.13.0](/python/docs/reference/compute/1.13.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.12.1](/python/docs/reference/compute/1.12.1/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.11.0](/python/docs/reference/compute/1.11.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.10.1](/python/docs/reference/compute/1.10.1/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.9.0](/python/docs/reference/compute/1.9.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.8.0](/python/docs/reference/compute/1.8.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.7.0](/python/docs/reference/compute/1.7.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.6.1](/python/docs/reference/compute/1.6.1/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.5.2](/python/docs/reference/compute/1.5.2/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.4.0](/python/docs/reference/compute/1.4.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.3.2](/python/docs/reference/compute/1.3.2/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.2.0](/python/docs/reference/compute/1.2.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.1.0](/python/docs/reference/compute/1.1.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [1.0.0](/python/docs/reference/compute/1.0.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [0.9.0](/python/docs/reference/compute/0.9.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [0.8.0](/python/docs/reference/compute/0.8.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [0.7.0](/python/docs/reference/compute/0.7.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [0.6.0](/python/docs/reference/compute/0.6.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [0.5.0](/python/docs/reference/compute/0.5.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [0.4.2](/python/docs/reference/compute/0.4.2/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [0.3.0](/python/docs/reference/compute/0.3.0/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [0.2.1](/python/docs/reference/compute/0.2.1/google.cloud.compute_v1.types.BackendService.SessionAffinity)\n- [0.1.0](/python/docs/reference/compute/0.1.0/google.cloud.compute_v1.types.BackendService.SessionAffinity) \n\n SessionAffinity(value)\n\nType of session affinity to use. The default is NONE. Only NONE and\nHEADER_FIELD are supported when the backend service is referenced by\na URL map that is bound to target gRPC proxy that has\nvalidateForProxyless field set to true. For more details, see:\n`Session\nAffinity \u003chttps://cloud.google.com/load-balancing/docs/backend-service#session_affinity\u003e`__.\nsessionAffinity cannot be specified with haPolicy."]]