[8.x] [Fleet] add escapeMultilineString Handlebar helper (#195159)

x-pack/plugins/fleet/server/services/epm/agent/agent.test.ts

@@ -261,6 +261,80 @@ New lines and \\n escaped values.`,
     });
   });
 
+  describe('escape_multiline_string helper', () => {
+    it('should escape new lines', () => {
+      const streamTemplate = `
+      input: log
+      multiline_text: "{{escape_multiline_string multiline_text}}"
+            `;
+
+      const vars = {
+        multiline_text: {
+          type: 'textarea',
+          value: `This is a text with
+New lines and \n escaped values.`,
+        },
+      };
+
+      const output = compileTemplate(vars, streamTemplate);
+      expect(output).toEqual({
+        input: 'log',
+        multiline_text: `This is a text with
+New lines and 
+escaped values.`,
+      });
+    });
+
+    it('should escape single quotes', () => {
+      const streamTemplate = `
+      input: log
+      multiline_text: "{{escape_multiline_string multiline_text}}"
+            `;
+
+      const vars = {
+        multiline_text: {
+          type: 'textarea',
+          value: `This is a multiline text with
+'escaped values.'`,
+        },
+      };
+
+      const output = compileTemplate(vars, streamTemplate);
+      expect(output).toEqual({
+        input: 'log',
+        multiline_text: `This is a multiline text with
+''escaped values.''`,
+      });
+    });
+
+    it('should allow concatenation of multiline strings', () => {
+      const streamTemplate = `
+input: log
+multiline_text: "{{escape_multiline_string multiline_text}}{{escape_multiline_string "
+This is a concatenated text
+with new lines"}}"
+      `;
+
+      const vars = {
+        multiline_text: {
+          type: 'textarea',
+          value: `This is a text with
+New lines and\nescaped values.`,
+        },
+      };
+
+      const output = compileTemplate(vars, streamTemplate);
+      expect(output).toEqual({
+        input: 'log',
+        multiline_text: `This is a text with
+New lines and
+escaped values.
+This is a concatenated text
+with new lines`,
+      });
+    });
+  });
+
   describe('to_json helper', () => {
     const streamTemplate = `
 input: log

x-pack/plugins/fleet/server/services/epm/agent/agent.ts

@@ -131,6 +131,18 @@ function escapeStringHelper(str: string) {
 }
 handlebars.registerHelper('escape_string', escapeStringHelper);
 
+/**
+ * escapeMultilineStringHelper will escape a multiline string by doubling the newlines
+ * and escaping single quotes.
+ * This is useful when the string is multiline and needs to be escaped in a yaml file
+ * without wrapping it in single quotes.
+ */
+function escapeMultilineStringHelper(str: string) {
+  if (!str) return undefined;
+  return str.replace(/\'/g, "''").replace(/\n/g, '\n\n');
+}
+handlebars.registerHelper('escape_multiline_string', escapeMultilineStringHelper);
+
 // toJsonHelper will convert any object to a Json string.
 function toJsonHelper(value: any) {
   if (typeof value === 'string') {