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commit 4f9720e84b02ba47d0a1a131c13e45719e7ef151 Author: Masaori Koshiba <[email protected]> AuthorDate: Tue Jun 9 08:15:51 2026 +0900 Cleanup serving stale while origin server down (#13083) * Cleanup serving stale while origin server down * Address comments from Copilot * Clarify connection close (cherry picked from commit 494ff824dcce3bcbfae1239f70e9bf8b26aa4459) --- doc/admin-guide/files/records.yaml.en.rst | 3 + src/proxy/http/HttpTransact.cc | 19 +-- tests/gold_tests/cache/proxy_serve_stale.test.py | 3 + .../proxy_serve_stale_origin_down.replay.yaml | 161 +++++++++++++++++++++ 4 files changed, 170 insertions(+), 16 deletions(-) diff --git a/doc/admin-guide/files/records.yaml.en.rst b/doc/admin-guide/files/records.yaml.en.rst index cfb11e82cb..be630e72bb 100644 --- a/doc/admin-guide/files/records.yaml.en.rst +++ b/doc/admin-guide/files/records.yaml.en.rst @@ -1959,6 +1959,9 @@ Origin Server Connect Attempts :overridable: Specifies how long (in seconds) |TS| remembers that an origin server was unreachable. + During this window, if a stale cached response exists and its age is within the cached response's ``max-age`` plus + :ts:cv:`proxy.config.http.cache.max_stale_age`, |TS| serves the stale content directly + without attempting to contact the origin server. .. ts:cv:: CONFIG proxy.config.http.uncacheable_requests_bypass_parent INT 1 :reloadable: diff --git a/src/proxy/http/HttpTransact.cc b/src/proxy/http/HttpTransact.cc index fa2a9a7145..107a8dc823 100644 --- a/src/proxy/http/HttpTransact.cc +++ b/src/proxy/http/HttpTransact.cc @@ -2902,23 +2902,10 @@ HttpTransact::HandleCacheOpenReadHit(State *s) find_server_and_update_current_info(s); - // We do not want to try to revalidate documents if we think - // the server is down due to the something report problem - // - // Note: we only want to skip origin servers because 1) - // parent proxies have their own negative caching - // scheme & 2) If we skip down parents, every page - // we serve is potentially stale - // - if (s->current.request_to == ResolveInfo::ORIGIN_SERVER && is_server_negative_cached(s) && response_returnable == true && - is_stale_cache_response_returnable(s) == true) { - server_up = false; - update_current_info(&s->current, nullptr, ResolveInfo::UNDEFINED_LOOKUP, true); - TxnDbg(dbg_ctl_http_trans, "CacheOpenReadHit - server_down, returning stale document"); - } - // a parent lookup could come back as ParentResultType::FAIL if in parent.config, go_direct == false and + // For origin servers (ResolveInfo::ORIGIN_SERVER): OSDNSLookup handles serving stale when all origin servers are down. + // For parent proxies: a parent lookup could come back as ParentResultType::FAIL if in parent.config, go_direct == false and // there are no available parents (all down). - else if (s->current.request_to == ResolveInfo::HOST_NONE && s->parent_result.result == ParentResultType::FAIL) { + if (s->current.request_to == ResolveInfo::HOST_NONE && s->parent_result.result == ParentResultType::FAIL) { if (response_returnable == true && is_stale_cache_response_returnable(s) == true) { server_up = false; update_current_info(&s->current, nullptr, ResolveInfo::UNDEFINED_LOOKUP, true); diff --git a/tests/gold_tests/cache/proxy_serve_stale.test.py b/tests/gold_tests/cache/proxy_serve_stale.test.py index 43c0bebd54..95e620a204 100644 --- a/tests/gold_tests/cache/proxy_serve_stale.test.py +++ b/tests/gold_tests/cache/proxy_serve_stale.test.py @@ -22,3 +22,6 @@ Test.ContinueOnFail = True # Verify that stale content is served when the parent is down. Test.ATSReplayTest(replay_file="replay/proxy_serve_stale.replay.yaml") + +# Verify that stale content is served when the origin server is down. +Test.ATSReplayTest(replay_file="replay/proxy_serve_stale_origin_down.replay.yaml") diff --git a/tests/gold_tests/cache/replay/proxy_serve_stale_origin_down.replay.yaml b/tests/gold_tests/cache/replay/proxy_serve_stale_origin_down.replay.yaml new file mode 100644 index 0000000000..c1ca7e90ea --- /dev/null +++ b/tests/gold_tests/cache/replay/proxy_serve_stale_origin_down.replay.yaml @@ -0,0 +1,161 @@ +# Licensed to the Apache Software Foundation (ASF) under one +# or more contributor license agreements. See the NOTICE file +# distributed with this work for additional information +# regarding copyright ownership. The ASF licenses this file +# to you under the Apache License, Version 2.0 (the +# "License"); you may not use this file except in compliance +# with the License. You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. + +meta: + version: "1.0" + +autest: + description: 'Verify that stale content is served when the origin server is down' + + dns: + name: 'dns-serve-stale-origin-down' + records: + backend.example.com: ["127.0.0.1"] + + + server: + name: 'server-serve-stale-origin-down' + + client: + name: 'client-serve-stale-origin-down' + + ats: + name: 'ts-serve-stale-origin-down' + process_config: + enable_cache: true + + records_config: + proxy.config.diags.debug.enabled: 1 + proxy.config.diags.debug.tags: 'cache|http|dns|hostdb' + proxy.config.http.cache.max_stale_age: 10 + proxy.config.http.connect.down.policy: 4 + proxy.config.http.connect_attempts_timeout: 1 + proxy.config.http.connect_attempts_rr_retries: 0 + proxy.config.http.connect_attempts_max_retries: 1 + proxy.config.http.connect_attempts_max_retries_down_server: 0 + proxy.config.http.down_server.cache_time: 5 + + remap_config: + - from: "http://example.com/"; + to: "http://backend.example.com:{SERVER_HTTP_PORT}/"; + + plugin_config: + - 'xdebug.so --enable=x-cache,x-cache-key,via' + +sessions: +- transactions: + # 1. Cache object + # cache-key: /path/a/ + # cache: miss + # origin server: up + - client-request: + method: "GET" + version: "1.1" + url: /path/a/ + headers: + fields: + - [ Host, example.com ] + - [ x-debug, "x-cache,x-cache-key,via" ] + - [ uuid, a-1 ] + + server-response: + status: 200 + headers: + fields: + - [ Content-Length, 16 ] + - [ Cache-Control, "public, max-age=1" ] + - [ Connection, close ] + + proxy-response: + status: 200 + headers: + fields: + - [ X-Cache, { value: miss, as: equal } ] + + # 2. Make the origin server down + # cache-key: /path/b/ + # cache: miss + # origin server: down + - client-request: + method: "GET" + version: "1.1" + url: /path/b/ + headers: + fields: + - [ Host, example.com ] + - [ x-debug, "x-cache,x-cache-key,via" ] + - [ uuid, b-1 ] + + server-response: + on_connect: reset + + proxy-response: + status: 502 + headers: + fields: + - [ X-Cache, { value: miss, as: equal } ] + + # 3. Serve stale while proxy.config.http.down_server.cache_time + # cache-key: /path/a/ + # cache: stale + # origin server: down (cached) + - client-request: + delay: 2s + method: "GET" + version: "1.1" + url: /path/a/ + headers: + fields: + - [ Host, example.com ] + - [ x-debug, "x-cache,x-cache-key,via" ] + - [ uuid, a-2 ] + + proxy-request: + expect: absent + + server-response: + on_connect: reset + + proxy-response: + status: 200 + headers: + fields: + - [ X-Cache, { value: hit-stale, as: equal } ] + + # 4. Revalidate stale contents + # cache-key: /path/a/ + # cache: stale + # origin server: up + - client-request: + delay: 5s + method: "GET" + version: "1.1" + url: /path/a/ + headers: + fields: + - [ Host, example.com ] + - [ x-debug, "x-cache,x-cache-key,via" ] + - [ uuid, a-99 ] + + server-response: + status: 304 + + proxy-response: + status: 200 + headers: + fields: + - [ X-Cache, { value: hit-stale, as: equal } ] +
