Allow to control the order of shared_preload_libraries (citus)

internal/patroni/config.go

@@ -20,6 +20,8 @@ import (
 	"path"
 	"strings"
 
+	"golang.org/x/exp/slices"
+
 	corev1 "k8s.io/api/core/v1"
 	"sigs.k8s.io/yaml"
 
@@ -231,10 +233,34 @@ func DynamicConfiguration(
 			// shared_preload_libraries is a comma separated list that can have
 			// other values appended in addition to the mandatory values. Below,
 			// any values provided in the CRD are appended after the mandatory
-			// values.
+			// values unless unless a mandatory value appear in the other list.
+			// The order defined by the shared_preload_libraries list is preserved
+			// (and leading when there is intersection with the mandatory values.)
+			// for example:
+			// 		v = "lib1, lib2, lib3"
+			//      s = "lib4, lib5, lib6"
+			//           => "lib1, lib2, lib3, lib4, lib5, lib6"
+			// 		v = "lib1, lib2, lib3"
+			//      s = "lib4, lib1, lib6"
+			//           => "lib2, lib3, lib1, lib5, lib6"
+			// 		v = "lib1, lib2, lib3"
+			//      s = "lib3, lib1, lib2"
+			//           => "lib3, lib1, lib2"
+
 			s, ok := parameters[k].(string)
 			if k == "shared_preload_libraries" && ok {
-				parameters[k] = v + "," + s
+				mandatoryLibraries := strings.Split(strings.ReplaceAll(v, " ", ""), ",")
+				definedlibraries := strings.Split(strings.ReplaceAll(s, " ", ""), ",")
+
+				nonDefinedMandatoryLibraries := make([]string, 0)
+
+				for _, value := range mandatoryLibraries {
+					if !slices.Contains(definedlibraries, value) {
+						nonDefinedMandatoryLibraries = append(nonDefinedMandatoryLibraries, value)
+					}
+				}
+
+				parameters[k] = strings.Join(append(nonDefinedMandatoryLibraries, definedlibraries...), ", ")
 			} else {
 				parameters[k] = v
 			}

internal/patroni/config_test.go

@@ -420,6 +420,60 @@ func TestDynamicConfiguration(t *testing.T) {
 					"use_slots":     false,
 				},
 			},
+			{
+				name: "postgresql.parameters: mandatory shared_preload_libraries containing a mandatory",
+				input: map[string]interface{}{
+					"postgresql": map[string]interface{}{
+						"parameters": map[string]interface{}{
+							"shared_preload_libraries": "given1, mandatory1, given2",
+						},
+					},
+				},
+				params: postgres.Parameters{
+					Mandatory: parameters(map[string]string{
+						"shared_preload_libraries": "mandatory1, mandatory2, mandatory3",
+					}),
+				},
+				expected: map[string]interface{}{
+					"loop_wait": int32(10),
+					"ttl":       int32(30),
+					"postgresql": map[string]interface{}{
+						"parameters": map[string]interface{}{
+							"shared_preload_libraries": "mandatory2, mandatory3, given1, mandatory1, given2",
+						},
+						"pg_hba":        []string{},
+						"use_pg_rewind": true,
+						"use_slots":     false,
+					},
+				},
+			},
+			{
+				name: "postgresql.parameters: mandatory shared_preload_libraries order from shared_preload_libraries, no duplicates",
+				input: map[string]interface{}{
+					"postgresql": map[string]interface{}{
+						"parameters": map[string]interface{}{
+							"shared_preload_libraries": "mandatory2, mandatory3, mandatory1",
+						},
+					},
+				},
+				params: postgres.Parameters{
+					Mandatory: parameters(map[string]string{
+						"shared_preload_libraries": "mandatory1, mandatory2, mandatory3",
+					}),
+				},
+				expected: map[string]interface{}{
+					"loop_wait": int32(10),
+					"ttl":       int32(30),
+					"postgresql": map[string]interface{}{
+						"parameters": map[string]interface{}{
+							"shared_preload_libraries": "mandatory2, mandatory3, mandatory1",
+						},
+						"pg_hba":        []string{},
+						"use_pg_rewind": true,
+						"use_slots":     false,
+					},
+				},
+			},		
 		},
 		{
 			name: "postgresql.pg_hba: wrong-type is ignored",