Just some follow up - in case anyone else is looking for solutions.
There are no obvious usage scenarios documented, but I found a solution
using a lb_policy of "ring_hash" where the client provides a header that is
unique the client. Just generate a unique, stable identifier throughout the
lifetime of the client (browser) and inject that as a header (here using
"x-session-hash", but it could be anything) into every request.
I'm using nanoid to generate unique strings in Javascript. I simply
generate one and store in local storage.
Here's the relevant .yaml for an example configuration that defines a
two-host upstream cluster:
admin:
access_log_path: /tmp/admin_access.log
address:
socket_address: { address: 0.0.0.0, port_value: 9901 }
static_resources:
listeners:
- name: listener_0
address:
socket_address: { address: 0.0.0.0, port_value: 8080 }
filter_chains:
- filters:
- name: envoy.filters.network.http_connection_manager
typed_config:
"@type":
type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager
codec_type: auto
stat_prefix: ingress_http
route_config:
name: local_route
virtual_hosts:
- name: local_service
domains: ["*"]
routes:
- match: { prefix: "/" }
route:
cluster: controlweb_backendservice
hash_policy:
- header:
header_name: x-session-hash
max_stream_duration:
grpc_timeout_header_max: 0s
cors:
allow_origin_string_match:
- prefix: "*"
allow_methods: GET, PUT, DELETE, POST, OPTIONS
allow_headers:
keep-alive,user-agent,cache-control,content-type,content-transfer-encoding,access-token,x-accept-content-transfer-encoding,x-accept-response-streaming,x-user-agent,x-grpc-web,grpc-timeout,x-session-hash
max_age: "1728000"
expose_headers: access-token,grpc-status,grpc-message
http_filters:
- name: envoy.filters.http.grpc_web
- name: envoy.filters.http.cors
- name: envoy.filters.http.router
clusters:
- name: controlweb_backendservice
connect_timeout: 0.25s
type: strict_dns
http2_protocol_options: {}
lb_policy: ring_hash
load_assignment:
cluster_name: cluster_0
endpoints:
- lb_endpoints:
- endpoint:
address:
socket_address:
address: 172.16.0.219
port_value: 50251
load_balancing_weight: 10
- endpoint:
address:
socket_address:
address: 172.16.0.132
port_value: 50251
load_balancing_weight: 1
On Sunday, February 14, 2021 at 12:43:42 PM UTC-5 Rob Cecil wrote:
> Looking for an example of an Envoy configuration that implements session
> affinity (stickiness) to load balance a cluster of backend servers. Thanks!
>
> I'm open to using the source IP or something in the header, but probably
> not cookie.
>
> Thanks
>
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