env_vars_from_overrides to sort deterministically

Author: adwk67

rust/operator-binary/src/airflow_controller.rs

@@ -1307,12 +1307,45 @@ fn add_git_sync_resources(
 
 /// Convert user-supplied `envOverrides` into a list of [`EnvVar`]s.
 fn env_vars_from_overrides(env_overrides: &HashMap<String, String>) -> Vec<EnvVar> {
+    // Collect into a `BTreeMap` first so the env vars come out in a deterministic (sorted) order;
+    // `HashMap` iteration order is randomised per instance and would otherwise churn the containers
+    // this feeds between reconciles. Mirrors the override handling in `env_vars.rs`.
     env_overrides
         .iter()
+        .collect::<BTreeMap<_, _>>()
+        .into_iter()
         .map(|(k, v)| EnvVar {
             name: k.clone(),
             value: Some(v.clone()),
             ..EnvVar::default()
         })
         .collect()
 }
+
+#[cfg(test)]
+mod tests {
+    use std::collections::HashMap;
+
+    use super::env_vars_from_overrides;
+
+    /// The env vars must come out in a deterministic (sorted-by-name) order. `env_overrides` is a
+    /// `HashMap`, whose iteration order is randomised per instance, so iterating it directly would
+    /// vary the rendered env array between reconciles and churn the git-sync containers it feeds.
+    #[test]
+    fn env_vars_from_overrides_are_sorted_by_name() {
+        let overrides = HashMap::from([
+            ("CHARLIE".to_string(), "3".to_string()),
+            ("ALPHA".to_string(), "1".to_string()),
+            ("ECHO".to_string(), "5".to_string()),
+            ("BRAVO".to_string(), "2".to_string()),
+            ("DELTA".to_string(), "4".to_string()),
+        ]);
+
+        let names: Vec<String> = env_vars_from_overrides(&overrides)
+            .into_iter()
+            .map(|env_var| env_var.name)
+            .collect();
+
+        assert_eq!(names, ["ALPHA", "BRAVO", "CHARLIE", "DELTA", "ECHO"]);
+    }
+}