[Canvas] - Allow timelion data source to use configured certificateAuthorities (#26809)

* allow timelion data source to use configured certificateAuthorities

* make it obvious that this is a temporary measure

* fix lint error

* Update src/legacy/core_plugins/interpreter/server/lib/create_handlers.js

Co-Authored-By: legrego <lgregorydev@gmail.com>

* fix lint error from comment updated via GH

src/legacy/core_plugins/interpreter/server/lib/create_handlers.js

@@ -27,6 +27,9 @@ export const createHandlers = (request, server) => {
 
   return {
     environment: 'server',
+    // TODO: https://github.com/elastic/kibana/issues/27437 - A temporary measure to allow the timelion data source to negotiate secure connections to the Kibana server, to be removed by 6.7
+    // See https://github.com/elastic/kibana/pull/26809 and https://github.com/elastic/kibana/issues/26812
+    __dangerouslyUnsupportedSslConfig: server.config().get('server.ssl'),
     serverUri:
       config.has('server.rewriteBasePath') && config.get('server.rewriteBasePath')
         ? `${server.info.uri}${config.get('server.basePath')}`

x-pack/plugins/canvas/canvas_plugin_src/functions/server/src/timelion.js

@@ -4,10 +4,28 @@
  * you may not use this file except in compliance with the Elastic License.
  */
 
-import { flatten } from 'lodash';
+import https from 'https';
+import { readFileSync } from 'fs';
+import _, { flatten } from 'lodash';
 import { fetch } from '../../../../common/lib/fetch';
 import { buildBoolArray } from '../../../../server/lib/build_bool_array';
 
+const readFile = file => readFileSync(file, 'utf8');
+
+function parseConfig(sslConfig = {}) {
+  const config = {
+    ssl: {
+      rejectUnauthorized: true,
+    },
+  };
+
+  if (_.size(_.get(sslConfig, 'certificateAuthorities'))) {
+    config.ssl.ca = sslConfig.certificateAuthorities.map(readFile);
+  }
+
+  return config;
+}
+
 export const timelion = () => ({
   name: 'timelion',
   context: {
@@ -77,6 +95,7 @@ export const timelion = () => ({
         ...handlers.httpHeaders,
       },
       data: body,
+      httpsAgent: new https.Agent(parseConfig(handlers.__dangerouslyUnsupportedSslConfig).ssl),
     }).then(resp => {
       const seriesList = resp.data.sheet[0].list;