My favorite configuration for gitian building is Linux Mint 19.1 (based on Ubuntu 18.04) with LXC 3.0.3.
Faced disk space issues. This gitian-builder patch works well:
diff --git a/bin/make-base-vm b/bin/make-base-vm
index 916c11f..152f8bc 100755
--- a/bin/make-base-vm
+++ b/bin/make-base-vm
@@ -264,7 +264,7 @@ if [ $LXC = "1" ]; then
fi
fi
fi
- dd if=/dev/zero of=$OUT-lxc bs=1M count=1 seek=10240
+ dd if=/dev/zero of=$OUT-lxc bs=1M count=1 seek=15360
/sbin/mkfs.ext4 -F $OUT-lxc
t=`mktemp -d gitian.XXXXXXXX`
sudo mount $OUT-lxc $t
Refs: