Add a ca-derivations required machine feature

Make ca-derivations require a `ca-derivations` machine feature, and
ca-aware builders expose it.

That way, a network of builders can mix ca-aware and non-ca-aware
machines, and the scheduler will send them in the right place.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/libstore/parsed-derivations.cc b/src/libstore/parsed-derivations.cc
index c5c3ae3dc..5e383a9a4 100644
--- a/src/libstore/parsed-derivations.cc
+++ b/src/libstore/parsed-derivations.cc
@@ -91,6 +91,8 @@ StringSet ParsedDerivation::getRequiredSystemFeatures() const
     StringSet res;
     for (auto & i : getStringsAttr("requiredSystemFeatures").value_or(Strings()))
         res.insert(i);
+    if (!derivationHasKnownOutputPaths(drv.type()))
+        res.insert("ca-derivations");
     return res;
 }