Revert "Add a replacement mechanism to work around nil handling in uc…

…fg (elastic#4041)" (elastic#5044)

Since elastic/go-ucfg v0.8.4 now correctly renders empty arrays, we no longer need the nil replacement mechanism work around (elastic#4041).
Also updates the unit test TestCanonicalConfig_Render to cover that the configuration with an empty array works.

pkg/controller/common/settings/canonical_config.go

@@ -155,20 +155,15 @@ func (c *CanonicalConfig) HasKeys(keys []string) []string {
 
 // Render returns the content of the configuration file,
 // with fields sorted alphabetically
-func (c *CanonicalConfig) Render(rs ...Replacement) ([]byte, error) {
+func (c *CanonicalConfig) Render() ([]byte, error) {
 	if c == nil {
 		return []byte{}, nil
 	}
-
 	var out untypedDict
 	err := c.asUCfg().Unpack(&out)
 	if err != nil {
 		return []byte{}, err
 	}
-
-	for _, r := range rs {
-		r.apply(out)
-	}
 	return yaml.Marshal(out)
 }
 

pkg/controller/common/settings/canonical_config_test.go

@@ -12,10 +12,11 @@ import (
 )
 
 func TestCanonicalConfig_Render(t *testing.T) {
-	config := MustCanonicalConfig(map[string]string{
+	config := MustCanonicalConfig(map[string]interface{}{
 		"aaa":        "aa  a",
 		"bbb":        "b  bb",
 		"aab":        "a a a",
+		"key":        map[string]interface{}{"emptyarray": []string{}},
 		"withquotes": "aa\"bb\"aa",
 		"zz":         "zzz  z z z",
 	})
@@ -24,10 +25,12 @@ func TestCanonicalConfig_Render(t *testing.T) {
 	expected := []byte(`aaa: aa  a
 aab: a a a
 bbb: b  bb
+key:
+  emptyarray: []
 withquotes: aa"bb"aa
 zz: zzz  z z z
 `)
-	require.Equal(t, expected, output)
+	require.Equal(t, string(expected), string(output))
 }
 
 func TestCanonicalConfig_MergeWith(t *testing.T) {

pkg/controller/elasticsearch/settings/canonical_config.go

@@ -10,18 +10,6 @@ import (
 	"github.com/elastic/cloud-on-k8s/pkg/controller/common/version"
 )
 
-// replaceNilNodeRoles works around a rendering issue with 0-sized string arrays/slices
-// that have gone through ucfg and have been reduced to nil.
-// Elasticsearch's new node.roles syntax relies on empty string arrays in YAML to express
-// a coordinating only node. See https://github.com/elastic/cloud-on-k8s/issues/3718
-var replaceNilNodeRoles = common.Replacement{
-	Path: []string{
-		"node", "roles",
-	},
-	Expected:    nil,
-	Replacement: make([]string, 0),
-}
-
 // CanonicalConfig contains configuration for Elasticsearch ("elasticsearch.yml"),
 // as a hierarchical key-value configuration.
 type CanonicalConfig struct {

pkg/controller/elasticsearch/settings/config_volume.go

@@ -90,7 +90,7 @@ func ConfigSecret(es esv1.Elasticsearch, ssetName string, configData []byte) cor
 
 // ReconcileConfig ensures the ES config for the pod is set in the apiserver.
 func ReconcileConfig(client k8s.Client, es esv1.Elasticsearch, ssetName string, config CanonicalConfig) error {
-	rendered, err := config.Render(replaceNilNodeRoles)
+	rendered, err := config.Render()
 	if err != nil {
 		return err
 	}