[Ingest Manager] Add contains handlebar helper for conditional blocks…

… in yaml (#72698) (#73131)

* Add contains handlebar helper for conditionally adding blocks in ingest manager yaml

* Split into two tests and sandbox handlebars runtime

* Make helper a little bit more robust and the any explicit

* Add this to function signature with explicit any type

* Update x-pack/plugins/ingest_manager/server/services/epm/agent/agent.ts

Co-authored-by: Nicolas Chaulet <n.chaulet@gmail.com>

Co-authored-by: Nicolas Chaulet <n.chaulet@gmail.com>
Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>

Co-authored-by: Nicolas Chaulet <n.chaulet@gmail.com>
Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>

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

@@ -84,6 +84,67 @@ foo: bar
     });
   });
 
+  describe('contains blocks', () => {
+    const streamTemplate = `
+input: log
+paths:
+{{#each paths}}
+  - {{this}}
+{{/each}}
+exclude_files: [".gz$"]
+tags:
+{{#each tags}}
+  - {{this}}
+{{/each}}
+{{#contains "forwarded" tags}}
+publisher_pipeline.disable_host: true
+{{/contains}}
+processors:
+  - add_locale: ~
+password: {{password}}
+{{#if password}}
+hidden_password: {{password}}
+{{/if}}
+      `;
+
+    it('should support when a value is not contained in the array', () => {
+      const vars = {
+        paths: { value: ['/usr/local/var/log/nginx/access.log'] },
+        password: { type: 'password', value: '' },
+        tags: { value: ['foo', 'bar', 'forwarded'] },
+      };
+
+      const output = createStream(vars, streamTemplate);
+      expect(output).toEqual({
+        input: 'log',
+        paths: ['/usr/local/var/log/nginx/access.log'],
+        exclude_files: ['.gz$'],
+        processors: [{ add_locale: null }],
+        password: '',
+        'publisher_pipeline.disable_host': true,
+        tags: ['foo', 'bar', 'forwarded'],
+      });
+    });
+
+    it('should support when a value is contained in the array', () => {
+      const vars = {
+        paths: { value: ['/usr/local/var/log/nginx/access.log'] },
+        password: { type: 'password', value: '' },
+        tags: { value: ['foo', 'bar'] },
+      };
+
+      const output = createStream(vars, streamTemplate);
+      expect(output).toEqual({
+        input: 'log',
+        paths: ['/usr/local/var/log/nginx/access.log'],
+        exclude_files: ['.gz$'],
+        processors: [{ add_locale: null }],
+        password: '',
+        tags: ['foo', 'bar'],
+      });
+    });
+  });
+
   it('should support optional yaml values at root level', () => {
     const streamTemplate = `
 input: logs

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

@@ -8,10 +8,12 @@ import Handlebars from 'handlebars';
 import { safeLoad, safeDump } from 'js-yaml';
 import { PackageConfigConfigRecord } from '../../../../common';
 
+const handlebars = Handlebars.create();
+
 export function createStream(variables: PackageConfigConfigRecord, streamTemplate: string) {
   const { vars, yamlValues } = buildTemplateVariables(variables, streamTemplate);
 
-  const template = Handlebars.compile(streamTemplate, { noEscape: true });
+  const template = handlebars.compile(streamTemplate, { noEscape: true });
   let stream = template(vars);
   stream = replaceRootLevelYamlVariables(yamlValues, stream);
 
@@ -87,6 +89,16 @@ function buildTemplateVariables(variables: PackageConfigConfigRecord, streamTemp
   return { vars, yamlValues };
 }
 
+function containsHelper(this: any, item: string, list: string[], options: any) {
+  if (Array.isArray(list) && list.includes(item)) {
+    if (options && options.fn) {
+      return options.fn(this);
+    }
+  }
+  return '';
+}
+handlebars.registerHelper('contains', containsHelper);
+
 function replaceRootLevelYamlVariables(yamlVariables: { [k: string]: any }, yamlTemplate: string) {
   if (Object.keys(yamlVariables).length === 0 || !yamlTemplate) {
     return yamlTemplate;