Support HTTP2 REFUSED_STREAM to allow for retry of non-idempotent requests about envoy HOT 4 CLOSED

Right now we only have a retry policy which includes all 5xx (all resets before headers result in a 5xx). We can definitely add a retry policy just for certain reset types (including REFUSED_STREAM):
https://github.com/lyft/envoy/blob/master/source/common/router/retry_state_impl.cc#L81

from envoy.

All 5xx seems a little dangerous? Internal Server Error & Gateway Timeout leave plenty of scope for the call to have had some effect on state.

from envoy.

We don't do any retries by default (mainly because of idempotency concerns per your point). The retry policies are configurable on a per route and per request basis. See here:
https://lyft.github.io/envoy/docs/configuration/http_filters/router_filter.html#x-envoy-retry-on
https://lyft.github.io/envoy/docs/configuration/http_conn_man/route_config/route.html#config-http-conn-man-route-table-route-retry

We do have many people who want the "5xx" policy since they know that the calls they are making are idempotent. At Lyft we also use the "connect-failure" policy almost everywhere since that is guaranteed to be idempotent.

It is very easy to add a new policy and we can definitely add one for a REFUSED_STREAM reset.

from envoy.

#74

from envoy.