Improve OpenTelemetry Collector JSON Marshalling

.chloggen/3281-marshal-config.yaml

@@ -0,0 +1,38 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. collector, target allocator, auto-instrumentation, opamp, github action)
+component: operator
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Fix Configuration marshalling for v1beta1 OpenTelemetryCollector instances.
+
+# One or more tracking issues related to the change
+issues: [3281]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: |
+  Previously, the v1beta1 OpenTelemetryCollector CR's config field was incorrectly
+  marshalled, potentially causing issues when storing in etcd or retrieving via kubectl.
+  This fix ensures that the config is properly marshalled, maintaining the correct
+  structure and data types. For example, a config with nested maps and arrays will now
+  be correctly preserved when stored and retrieved, instead of being flattened or
+  losing structure.
+
+  As an example, configuration like this:
+
+  receivers:
+      otlp:
+        protocols:
+          grpc:
+          http:
+
+  Would be retrieved from the Kubernetes cluster as:
+
+  receivers:
+      otlp:
+        protocols:
+
+  The specified protocols were not there anymore before this fix.

apis/v1beta1/config.go

@@ -90,11 +90,17 @@ func (c *AnyConfig) UnmarshalJSON(b []byte) error {
 }
 
 // MarshalJSON specifies how to convert this object into JSON.
-func (c *AnyConfig) MarshalJSON() ([]byte, error) {
-	if c == nil {
+func (c AnyConfig) MarshalJSON() ([]byte, error) {
+	if c.Object == nil {
 		return []byte("{}"), nil
 	}
-	return json.Marshal(c.Object)
+
+	nonNilMap := make(map[string]interface{}, len(c.Object))
+	for k, v := range c.Object {
+		nonNilMap[k] = v
+	}
+
+	return json.Marshal(nonNilMap)
 }
 
 // Pipeline is a struct of component type to a list of component IDs.
@@ -280,6 +286,27 @@ func (c *Config) Yaml() (string, error) {
 	return buf.String(), nil
 }
 
+// MarshalJSON marshalls the Config field.
+func (c Config) MarshalJSON() ([]byte, error) {
+	// When you marshal a struct that embeds itself or a type that directly or indirectly refers back to itself,
+	// Go's JSON marshaling can lead to infinite recursion. To avoid this, we create an alias of the struct
+	// (Config), so Go no longer considers it the same type.
+	// This allows you to embed the struct safely within itself without triggering that infinite loop.
+	type Alias Config
+	// Ensure we call the custom marshaller for AnyConfig for the Receivers
+	receiversJSON, err := json.Marshal(c.Receivers)
+	if err != nil {
+		return nil, err
+	}
+	return json.Marshal(&struct {
+		*Alias
+		Receivers json.RawMessage `json:"receivers,omitempty"`
+	}{
+		Alias:     (*Alias)(&c),
+		Receivers: receiversJSON,
+	})
+}
+
 // Returns null objects in the config.
 func (c *Config) nullObjects() []string {
 	var nullKeys []string