Remove common key in yaml and deep merge logic; recommend yaml anchors

Author: labrenbe

rust/stackable-cockpit/src/platform/release/spec.rs

@@ -19,7 +19,7 @@ use crate::{
     utils::{
         k8s::{self, Client},
         path::{IntoPathOrUrl as _, PathOrUrlParseError},
-        yaml::merged_values_for_operator,
+        yaml::values_for_operator,
     },
     xfer::{self, processor::Text},
 };
@@ -111,7 +111,7 @@ impl ReleaseSpec {
 
                 let namespace = namespace.clone();
                 let chart_source = chart_source.clone();
-                let merged_values = merged_values_for_operator(operator_values, &product_name);
+                let operator_helm_values = values_for_operator(operator_values, &product_name);
                 // Helm installs currently `block_in_place`, so we need to spawn each job onto a separate task to
                 // get useful parallelism.
                 tokio::spawn(
@@ -126,7 +126,7 @@ impl ReleaseSpec {
 
                         // Install operator
                         operator
-                            .install(&namespace, &chart_source, &merged_values)
+                            .install(&namespace, &chart_source, &operator_helm_values)
                             .context(HelmInstallSnafu)?;
 
                         info!("Installed {product_name}-operator");

rust/stackable-cockpit/src/utils/yaml.rs

@@ -1,50 +1,13 @@
 use serde_yaml::{Mapping, Value};
 
-/// Extracts the merged Helm values for a specific operator from the operator values mapping.
+/// Extracts the Helm values for a specific operator from the operator values mapping.
 ///
-/// Looks up the `common` key and the operator-specific key (e.g. `airflow-operator`),
-/// then deep-merges them with operator-specific values taking precedence.
-pub fn merged_values_for_operator(operator_values: &Mapping, operator_name: &str) -> Mapping {
-    let common = operator_values
-        .get("common")
-        .and_then(Value::as_mapping)
-        .cloned()
-        .unwrap_or_default();
-    let operator_specific = operator_values
+/// Looks up the operator-specific key (e.g. `airflow-operator`) and returns
+/// the associated mapping, or an empty mapping if not found.
+pub fn values_for_operator(operator_values: &Mapping, operator_name: &str) -> Mapping {
+    operator_values
         .get(format!("{operator_name}-operator"))
         .and_then(Value::as_mapping)
         .cloned()
-        .unwrap_or_default();
-    deep_merge(common, operator_specific)
-}
-
-/// Deep merges `overlay` into `base`. Overlay values take precedence.
-/// When both values are mappings, their contents are merged recursively.
-/// Non-mapping values (including sequences) are replaced entirely, not merged.
-fn deep_merge(mut base: Mapping, overlay: Mapping) -> Mapping {
-    for (k, v) in overlay {
-        match base.get_mut(&k) {
-            Some(base_v) => merge_value(base_v, v),
-            None => {
-                base.insert(k, v);
-            }
-        }
-    }
-    base
-}
-
-fn merge_value(base: &mut Value, overlay: Value) {
-    match (base, overlay) {
-        (Value::Mapping(base), Value::Mapping(overlay)) => {
-            for (k, v) in overlay {
-                match base.get_mut(&k) {
-                    Some(base_v) => merge_value(base_v, v),
-                    None => {
-                        base.insert(k, v);
-                    }
-                }
-            }
-        }
-        (base, overlay) => *base = overlay,
-    }
+        .unwrap_or_default()
 }

rust/stackablectl/src/args/file.rs

@@ -48,22 +48,21 @@ to provide multiple additional release files.")]
     #[arg(
         long_help = "Path to a Helm values file that will be used for the installation of operators
 
-The file is a YAML file containing Helm values used to deploy operators. It
-supports a 'common' key for values shared across all operators, as well as
-operator-specific keys (e.g. 'airflow-operator', 'zookeeper-operator') for
-values that only apply to a single operator. Operator-specific values are
-merged with common values, with operator-specific values taking precedence.
+The file is a YAML file containing Helm values used to deploy operators.
+Operator-specific keys (e.g. 'airflow-operator', 'zookeeper-operator') map
+to the Helm values for that operator. Use YAML anchors and aliases to share
+values across operators.
 
 Example values file:
 
-  common:
-    tolerations:
+  airflow-operator:
+    tolerations: &default-tolerations
       - key: \"example\"
         operator: \"Exists\"
         effect: \"NoSchedule\"
-  airflow-operator:
     replicas: 2
   zookeeper-operator:
+    tolerations: *default-tolerations
     replicas: 3
 
 Use \"stackablectl [OPTIONS] <COMMAND> -f path/to/values.yaml\" to provide a

rust/stackablectl/src/cmds/operator.rs

@@ -24,7 +24,7 @@ use stackable_cockpit::{
         chartsource::ChartSourceMetadata,
         k8s::{self, Client},
         path::PathOrUrlParseError,
-        yaml::merged_values_for_operator,
+        yaml::values_for_operator,
     },
     xfer,
 };
@@ -351,13 +351,13 @@ async fn install_cmd(
         .context(LoadOperatorValuesSnafu)?;
 
     for operator in &args.operators {
-        let merged_values = merged_values_for_operator(&operator_values, &operator.name);
+        let operator_helm_values = values_for_operator(&operator_values, &operator.name);
 
         operator
             .install(
                 &args.operator_namespace,
                 &ChartSourceType::from(cli.chart_type()),
-                &merged_values,
+                &operator_helm_values,
             )
             .context(HelmSnafu)?;
 

rust/stackablectl/src/utils.rs

@@ -56,14 +56,18 @@ pub fn use_colored_output(use_color: bool) -> bool {
 
 /// Loads operator helm values from a YAML file.
 ///
-/// The file should contain a YAML mapping of operator names to their helm values:
+/// The file should contain a YAML mapping of operator names to their helm values.
+/// Use YAML anchors and aliases to share values across operators:
 /// ```yaml
-/// common:
-///   key: value
 /// airflow-operator:
-///   key: value
+///   tolerations: &default-tolerations
+///     - key: "example"
+///       operator: "Exists"
+///       effect: "NoSchedule"
+///   replicas: 2
 /// zookeeper-operator:
-///   key: value
+///   tolerations: *default-tolerations
+///   replicas: 3
 /// ```
 pub async fn load_operator_values(
     values_file: Option<&PathOrUrl>,