Fixes extra newline from confs

As we are using templates to dynamicaly create confs on conditions,
Often extra newlines are getting added in confs, we should remove them.

modules/common/util/template_util.go

@@ -57,6 +57,48 @@ type Template struct {
 	ConfigOptions      map[string]interface{} // map of parameters as input data to render the templates
 	SkipSetOwner       bool                   // skip setting ownership on the associated configmap
 	Version            string                 // optional version string to separate templates inside the InstanceType/Type directory. E.g. placementapi/config/18.0
+	PostRenderCleanup  bool                   // optional boolean parameter to remove extra new lines from service confs, by default set to false
+}
+
+// This function removes extra space and new-lines from conf data
+func removeSubsequentNewLines(rawConf string) string {
+	lines := strings.Split(rawConf, "\n")
+	var result []string
+	var prevLineWasBlank bool
+
+	for _, line := range lines {
+		trimmedLine := strings.TrimSpace(line)
+
+		if trimmedLine == "" {
+			prevLineWasBlank = true
+			// if current line is blank, no need to add it in result
+		} else {
+			if strings.HasPrefix(trimmedLine, "[") && strings.HasSuffix(trimmedLine, "]") {
+				// section-header
+				if len(result) > 0 && !prevLineWasBlank {
+					result = append(result, "")
+				}
+				var sectionHeaderLine string
+				if len(result) > 0 {
+					// new section-hearder
+					sectionHeaderLine = "\n" + line
+				} else {
+					sectionHeaderLine = line
+				}
+				result = append(result, sectionHeaderLine)
+			} else {
+				// secion-body
+				result = append(result, line)
+			}
+			// reset flag
+			prevLineWasBlank = false
+		}
+	}
+
+	// add an extra line at EOF
+	result = append(result, "")
+
+	return strings.Join(result, "\n")
 }
 
 // GetTemplatesPath get path to templates, either running local or deployed as container
@@ -135,6 +177,7 @@ func ExecuteTemplate(templateFile string, data interface{}) (string, error) {
 	if err != nil {
 		return "", err
 	}
+
 	return renderedTemplate, nil
 }
 
@@ -244,5 +287,14 @@ func GetTemplateData(t Template) (map[string]string, error) {
 		data[filename] = renderedTemplate
 	}
 
+	if t.PostRenderCleanup {
+		for filename, content := range data {
+			if strings.HasSuffix(filename, ".conf") {
+				// as of now, only clean for confs
+				data[filename] = removeSubsequentNewLines(content)
+			}
+		}
+	}
+
 	return data, nil
 }

modules/common/util/template_util_test.go

@@ -136,8 +136,10 @@ func TestGetTemplateData(t *testing.T) {
 					"Upper":       "BAR",
 				},
 				AdditionalTemplate: map[string]string{},
+				PostRenderCleanup:  true,
 			},
 			want: map[string]string{
+				"bar.conf":    "[DEFAULT]\nstate_path = /var/lib/nova\ndebug=true\ncompute_driver = libvirt.LibvirtDriver\n\n[oslo_concurrency]\nlock_path = /var/lib/nova/tmp\n",
 				"config.json": "{\n    \"command\": \"/usr/sbin/httpd -DFOREGROUND\",\n}\n",
 				"foo.conf":    "username = foo\ncount = 1\nadd = 3\nlower = bar\n",
 			},
@@ -173,11 +175,13 @@ func TestGetTemplateData(t *testing.T) {
 					"Message":     "some common func",
 				},
 				AdditionalTemplate: map[string]string{"common.sh": "/common/common.sh"},
+				PostRenderCleanup:  true,
 			},
 			want: map[string]string{
 				"config.json": "{\n    \"command\": \"/usr/sbin/httpd -DFOREGROUND\",\n}\n",
 				"foo.conf":    "username = foo\ncount = 1\nadd = 3\nlower = bar\n",
 				"common.sh":   "#!/bin/bash\nset -e\n\nfunction common_func {\n  echo some common func\n}\n",
+				"bar.conf":    "[DEFAULT]\nstate_path = /var/lib/nova\ndebug=true\ncompute_driver = libvirt.LibvirtDriver\n\n[oslo_concurrency]\nlock_path = /var/lib/nova/tmp\n",
 			},
 			error: false,
 		},

modules/common/util/testdata/templates/testservice/config/bar.conf

@@ -0,0 +1,13 @@
+[DEFAULT]
+state_path = /var/lib/nova
+
+
+debug=true
+
+compute_driver = libvirt.LibvirtDriver
+
+
+[oslo_concurrency]
+lock_path = /var/lib/nova/tmp
+
+