libstore: deprecate the build-hook setting

implementing a build hook is pretty much impossible without either being
a nix, or blindly forwarding the important bits of all build requests to
some kind of nix. we've found no uses of build-hook in the wild, and the
build-hook protocol (apart from being entirely undocumented) is not able
to convey any kind of versioning information between hook and daemon. if
we want to upgrade this infrastructure (which we do), this must not stay

Change-Id: I1ec4976a35adf8105b8ca9240b7984f8b91e147e

1 files changed, 8 insertions, 0 deletions

diff --git a/doc/manual/rl-next/deprecate-build-hook.md b/doc/manual/rl-next/deprecate-build-hook.md
new file mode 100644
index 000000000..30de1298d
--- /dev/null
+++ b/doc/manual/rl-next/deprecate-build-hook.md
@@ -0,0 +1,8 @@
+---
+synopsis: "The `build-hook` setting is now deprecated"
+category: Breaking Changes
+---
+
+Build hooks communicate with the daemon using a custom, internal, undocumented protocol that is entirely unversioned and cannot be changed.
+Since we intend to change it anyway we must unfortunately deprecate the current build hook infrastructure.
+We do not expect this to impact most users—we have not found any uses of `build-hook` in the wild—but if this does affect you, we'd like to hear from you!