2019-12-07 08:36:43 +00:00
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# Directives are registered in the order they should be executed.
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2017-01-31 12:25:02 -05:00
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#
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2019-12-07 08:36:43 +00:00
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# Ordering is VERY important. Every plugin will feel the effects of all other
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# plugin below (after) them during a request, but they must not care what plugin
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# above them are doing.
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2017-01-31 12:25:02 -05:00
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2019-12-07 08:36:43 +00:00
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# How to rebuild with updated plugin configurations: Modify the list below and
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# run `go generate && go build`
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2017-01-31 12:25:02 -05:00
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2019-12-07 08:36:43 +00:00
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# The parser takes the input format of:
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#
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2017-10-16 10:49:18 +02:00
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# <plugin-name>:<package-name>
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2017-02-19 20:34:29 +00:00
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# Or
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# <plugin-name>:<fully-qualified-package-name>
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2017-02-19 20:34:29 +00:00
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#
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2017-09-14 09:36:06 +01:00
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# External plugin example:
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#
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# log:github.com/coredns/coredns/plugin/log
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# Local plugin example:
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2017-10-16 10:49:18 +02:00
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# log:log
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2017-01-31 12:25:02 -05:00
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2023-12-08 16:50:30 +01:00
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root:root
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2018-06-29 12:44:16 +03:00
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metadata:metadata
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2021-07-14 08:25:30 +01:00
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geoip:geoip
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2019-03-29 19:40:23 +00:00
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cancel:cancel
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2026-03-31 00:43:31 +03:00
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proxyproto:proxyproto
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2025-05-19 03:49:21 +03:00
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quic:quic
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2025-12-18 05:08:59 +02:00
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grpc_server:grpc_server
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https:https
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https3:https3
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2022-12-28 11:14:16 +00:00
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timeouts:timeouts
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2024-11-13 20:40:25 +03:00
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multisocket:multisocket
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2018-03-02 17:17:26 -08:00
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reload:reload
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2017-12-04 08:28:27 -08:00
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nsid:nsid
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2019-11-10 08:10:12 +00:00
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bufsize:bufsize
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2017-10-16 10:49:18 +02:00
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bind:bind
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debug:debug
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trace:trace
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2019-03-07 20:35:16 +00:00
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ready:ready
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2017-10-16 10:49:18 +02:00
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health:health
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pprof:pprof
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plugin/shed: add UDP overload protection plugin (#8312)
* plugin/shed: add UDP overload protection plugin
UDP responses written back through one listener socket serialize on the
Go runtime's internal fdMutex, which allows at most 2^20-1 concurrent
operations per file descriptor and panics the process when exceeded.
CoreDNS serves UDP with one goroutine per query, all writing through the
shared packet connection, so a sustained overload parks every excess
in-flight query in that wait queue until the process dies with
"too many concurrent operations on a single file or socket". Observed
in production: ~2.8M goroutines and 60GiB RSS before the panic.
The shed plugin makes the panic structurally unreachable. It installs,
via Config.UDPDecorateWriterFunc, a per-socket bounded evict-oldest
stack drained newest-first by a single writer goroutine, so the fd
never sees more than one writer and residual capacity under overload
always goes to the freshest response. While a socket's stack is full,
arriving queries are dropped before any plugin runs. Drops are silent
(the client's resolver retries elsewhere) and counted in
coredns_shed_dropped_total{server, reason}.
plugin/shed/fdmutex_test.go demonstrates the failure and the fix with
one shared flood harness. Two subprocess tests reproduce the exact
runtime panic without the plugin's write discipline - one deterministic
(a held write plus >2^20 queued writers), one with nothing held or
mocked; both exercise the Go runtime rather than the plugin, so they
are gated behind SHED_FLOOD_TEST=1. The counterfactual - the same load
through the plugin's stack, completing with every response accounted
for as written or dropped - runs in every test invocation, including
-race, at 50k responders, and at the full 1.5M with SHED_FLOOD_TEST=1:
SHED_FLOOD_TEST=1 go test ./plugin/shed/
Signed-off-by: Ryan Brewster <rpb@anthropic.com>
* test: add shed e2e test
Query a shed-enabled server over UDP (the plugin's deferred
single-writer path) and TCP (which shed passes through), and check
that coredns_shed_dropped_total is exported with its reason label.
No-Verification-Needed: test-only change
Signed-off-by: Ryan Brewster <rpb@anthropic.com>
---------
Signed-off-by: Ryan Brewster <rpb@anthropic.com>
2026-07-27 05:13:25 -04:00
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shed:shed
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2017-10-16 10:49:18 +02:00
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prometheus:metrics
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errors:errors
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log:log
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dnstap:dnstap
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2020-11-05 15:02:07 +01:00
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local:local
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2020-03-26 08:42:23 +01:00
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dns64:dns64
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2026-08-24 02:55:27 +02:00
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siit:siit
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2019-04-28 11:46:45 +01:00
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any:any
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2017-10-16 10:49:18 +02:00
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chaos:chaos
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2018-01-11 19:59:56 +01:00
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loadbalance:loadbalance
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2022-06-27 15:48:34 -04:00
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tsig:tsig
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2017-10-16 10:49:18 +02:00
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rewrite:rewrite
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2026-07-14 22:36:06 -07:00
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autopath:autopath
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2026-02-25 10:19:47 +00:00
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acl:acl
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2026-07-14 22:26:49 -07:00
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cache:cache
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2021-07-15 09:32:39 +02:00
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header:header
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2017-10-16 10:49:18 +02:00
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dnssec:dnssec
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2026-07-30 10:24:22 +08:00
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# Keep tls here so dnssec can sign ACME challenge records before authoritative backends run.
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tls:tls
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2021-03-15 20:07:55 +05:30
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minimal:minimal
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2018-01-08 11:52:25 +01:00
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template:template
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2019-11-01 12:02:43 -04:00
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transfer:transfer
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2017-10-16 10:49:18 +02:00
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hosts:hosts
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2018-01-15 09:59:29 -08:00
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route53:route53
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2019-08-09 12:40:28 +05:30
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azure:azure
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2019-08-18 02:29:09 +05:30
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clouddns:clouddns
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2018-12-14 09:41:51 +00:00
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k8s_external:k8s_external
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2017-10-16 10:49:18 +02:00
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kubernetes:kubernetes
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file:file
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auto:auto
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secondary:secondary
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etcd:etcd
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2018-07-20 19:45:17 +01:00
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loop:loop
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2018-02-05 22:00:47 +00:00
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forward:forward
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2019-03-14 08:12:28 +01:00
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grpc:grpc
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2017-10-16 10:49:18 +02:00
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erratic:erratic
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whoami:whoami
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2020-09-24 18:14:41 +02:00
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on:github.com/coredns/caddy/onevent
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2019-08-29 15:41:59 +01:00
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sign:sign
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2022-09-08 14:56:27 -04:00
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view:view
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2025-09-30 18:35:32 +02:00
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nomad:nomad
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