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router: retry overloaded requests #10847

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merged 10 commits into from
Apr 22, 2020
Merged

router: retry overloaded requests #10847

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3801e21
retry overload requests
ramaraochavali Apr 19, 2020
a1bf01b
Merge remote-tracking branch 'upstream/master' into fix/retry_overload
ramaraochavali Apr 19, 2020
d22b56e
retry overload requests
ramaraochavali Apr 20, 2020
acf6885
format
ramaraochavali Apr 20, 2020
6bb3c6a
fix version history and correct docs
ramaraochavali Apr 21, 2020
e648a0d
Merge remote-tracking branch 'upstream/master' into fix/retry_overload
ramaraochavali Apr 21, 2020
69fc2da
resolve conflicts
ramaraochavali Apr 21, 2020
899d4a6
fix docs
ramaraochavali Apr 21, 2020
556ae19
kick ci
ramaraochavali Apr 21, 2020
998f8ed
review comments
ramaraochavali Apr 22, 2020
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8 changes: 0 additions & 8 deletions docs/root/configuration/http/http_filters/router_filter.rst
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Expand Up @@ -274,14 +274,6 @@ for the next health check interval. The host can become healthy again via standa
checks. See the :ref:`health checking overview <arch_overview_health_checking>` for more
information.

.. _config_http_filters_router_x-envoy-overloaded_consumed:

x-envoy-overloaded
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Is this header documented anywhere else? I think we still should document it. I think it does still make sense to send it as downstream may want to track it, but we should document somewhere?

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I checked earlier- it's explained further down in the same file.

^^^^^^^^^^^^^^^^^^

If this header is set by upstream, Envoy will not retry. Currently the value of the header is not
looked at, only its presence.

.. _config_http_filters_router_x-envoy-ratelimited:

x-envoy-ratelimited
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6 changes: 4 additions & 2 deletions docs/root/intro/arch_overview/http/http_routing.rst
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Expand Up @@ -122,8 +122,10 @@ headers <config_http_filters_router_headers_consumed>`. The following configurat
:ref:`retry priority <envoy_api_field_route.RetryPolicy.retry_priority>` can be
configured to adjust the priority load used when selecting a priority for retries.

Note that retries may be disabled depending on the contents of the :ref:`x-envoy-overloaded
<config_http_filters_router_x-envoy-overloaded_consumed>`.
Note that Envoy retries requests when :ref:`x-envoy-overloaded
<config_http_filters_router_x-envoy-overloaded_set>` is present. It is recommended to either configure
:ref:`retry budgets (preferred) <envoy_api_field_cluster.CircuitBreakers.Thresholds.retry_budget>` or set
:ref:`maximum active retries circuit breaker <arch_overview_circuit_break>` to an appropriate value avoid retry storms.
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Suggested change
:ref:`maximum active retries circuit breaker <arch_overview_circuit_break>` to an appropriate value avoid retry storms.
:ref:`maximum active retries circuit breaker <arch_overview_circuit_break>` to an appropriate value to avoid retry storms.


.. _arch_overview_http_routing_hedging:

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1 change: 1 addition & 0 deletions docs/root/version_history/current.rst
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Expand Up @@ -17,6 +17,7 @@ Changes
Can be reverted temporarily by setting runtime feature `envoy.reloadable_features.fix_upgrade_response` to false.
* network filters: added a :ref:`postgres proxy filter <config_network_filters_postgres_proxy>`.
* router: allow retries of streaming or incomplete requests. This removes stat `rq_retry_skipped_request_not_complete`.
* router: allow retries by default when upstream responds with :ref:`x-envoy-overloaded <config_http_filters_router_x-envoy-overloaded_set>`.
* tracing: tracing configuration has been made fully dynamic and every HTTP connection manager
can now have a separate :ref:`tracing provider <envoy_v3_api_field_extensions.filters.network.http_connection_manager.v3.HttpConnectionManager.Tracing.provider>`.

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4 changes: 0 additions & 4 deletions source/common/router/retry_state_impl.cc
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Expand Up @@ -281,10 +281,6 @@ RetryStatus RetryStateImpl::shouldHedgeRetryPerTryTimeout(DoRetryCallback callba
}

bool RetryStateImpl::wouldRetryFromHeaders(const Http::ResponseHeaderMap& response_headers) {
if (response_headers.EnvoyOverloaded() != nullptr) {
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Can you remove this from the O(1) header map? I think we don't need this anymore as the header can be added by string reference where it is added currently?

return false;
}

// We never retry if the request is rate limited.
if (response_headers.EnvoyRateLimited() != nullptr) {
return false;
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3 changes: 2 additions & 1 deletion test/common/router/retry_state_impl_test.cc
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Expand Up @@ -203,7 +203,8 @@ TEST_F(RouterRetryStateImplTest, Policy5xxRemote503Overloaded) {

Http::TestResponseHeaderMapImpl response_headers{{":status", "503"},
{"x-envoy-overloaded", "true"}};
EXPECT_EQ(RetryStatus::No, state_->shouldRetryHeaders(response_headers, callback_));
expectTimerCreateAndEnable();
EXPECT_EQ(RetryStatus::Yes, state_->shouldRetryHeaders(response_headers, callback_));
}

TEST_F(RouterRetryStateImplTest, PolicyResourceExhaustedRemoteRateLimited) {
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