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| author |  Miek Gieben <miek@miek.nl>
| 2019-11-15 14:14:29 +0000 |
|---|---|---|
| committer |  Chris O'Haver <cohaver@infoblox.com>
| 2019-11-15 09:14:29 -0500 |
| commit | 1e3330c12b285de45888942d8dd69c6e4253098e (patch) | |
| tree | 8960ba3664db82336a8c11ef99746454871215b6 | |
| parent | e1782c46e86908340179fff18def345f166c2826 (diff) | |
| download | coredns-1e3330c12b285de45888942d8dd69c6e4253098e.tar.gz coredns-1e3330c12b285de45888942d8dd69c6e4253098e.tar.zst coredns-1e3330c12b285de45888942d8dd69c6e4253098e.zip | |
pkg/fall: add (a lot of) guidance (#3450)
update the pkg doc to talk about various trade off
Fixes #2723
Signed-off-by: Miek Gieben <miek@miek.nl>
| -rw-r--r-- | plugin/pkg/fall/fall.go | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/plugin/pkg/fall/fall.go b/plugin/pkg/fall/fall.go index c8cdc6ff6..067deb9a6 100644 --- a/plugin/pkg/fall/fall.go +++ b/plugin/pkg/fall/fall.go @@ -1,4 +1,16 @@ -// Package fall handles the fallthrough logic used in plugins that support it. +// Package fall handles the fallthrough logic used in plugins that support it. Be careful when including this +// functionality in your plugin. Why? In the DNS only 1 source is authoritative for a set of names. Fallthrough +// breaks this convention by allowing a plugin to query multiple sources, depending on the replies it got sofar. +// +// This may cause issues in downstream caches, where different answers for the same query can potentially confuse clients. +// On the other hand this is a powerful feature that can aid in migration or other edge cases. +// +// The take away: be mindful of this and don't blindly assume it's a good feature to have in your plugin. +// +// See http://github.com/coredns/coredns/issues/2723 for some discussion on this, which includes this quote: +// +// TL;DR: `fallthrough` is indeed risky and hackish, but still a good feature of CoreDNS as it allows to quickly answer boring edge cases. +// package fall import ( |