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, 7 insertions, 0 deletions

diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index 93fcb068f..6ca8e5b24 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -337,6 +337,13 @@ ValidPathInfo Store::addToStoreSlow(std::string_view name, const Path & srcPath,
     return info;
 }
 
+StringSet StoreConfig::getDefaultSystemFeatures()
+{
+    auto res = settings.systemFeatures.get();
+    if (settings.isExperimentalFeatureEnabled("ca-derivations"))
+        res.insert("ca-derivations");
+    return res;
+}
 
 Store::Store(const Params & params)
     : StoreConfig(params)