From ff93613a3519f1abb9810aaef406fdc99d43033a Mon Sep 17 00:00:00 2001
From: David Lutterkort <lutter@watzmann.net>
Date: Wed, 25 Aug 2021 15:26:10 -0700
Subject: [PATCH] node: check that at least one replica for each shard has a
 non-zero weight

---
 node/src/config.rs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/node/src/config.rs b/node/src/config.rs
index 757b3d41b46..02ecdd9e5b5 100644
--- a/node/src/config.rs
+++ b/node/src/config.rs
@@ -231,6 +231,16 @@ impl Shard {
             validate_name(name).context("illegal replica name")?;
             replica.validate(&self.pool_size)?;
         }
+
+        let no_weight =
+            self.weight == 0 && self.replicas.values().all(|replica| replica.weight == 0);
+        if no_weight {
+            return Err(anyhow!(
+                "all weights for shard `{}` are 0; \
+                remove explicit weights or set at least one of them to a value bigger than 0",
+                name
+            ));
+        }
         Ok(())
     }