Add endpoint to get field mapping for given index.

Author: johnsusek

README.md

@@ -215,6 +215,10 @@ This server exposes the following REST API's:
 
     Returns metadata from elasticsearch related to elasalert's state. `:type` should be one of: elastalert_status, elastalert, elastalert_error, or silence. See [docs about the elastalert metadata index](https://elastalert.readthedocs.io/en/latest/elastalert_status.html).
 
+- **GET `/mapping/:index`**
+
+    Returns field mapping from elasticsearch for a given index. 
+
 - **[WIP] GET `/config`**
 
     Gets the ElastAlert configuration from `config.yaml` in `elastalertPath` (from the config).

src/handlers/mapping/get.js

@@ -0,0 +1,20 @@
+import { getClient } from '../../common/elasticsearch_client';
+
+var client = getClient();
+
+export default function metadataHandler(request, response) {
+  /**
+   * @type {ElastalertServer}
+   */
+  
+  client.indices.getMapping({
+    index: request.params.index
+  }).then(function(resp) {
+    response.send(resp);
+  }, function(err) {
+    response.send({
+      error: err
+    });
+  });
+
+}

src/handlers/metadata/get.js

@@ -3,19 +3,29 @@ import { getConfig, getClient } from '../../common/elasticsearch_client';
 var config = getConfig();
 var client = getClient();
 
+function getQueryString(request) {
+  if (request.params.type === 'elastalert_error') {
+    return '*:*';
+  }
+  else {
+    return `rule_name:${request.query.rule_name || '*'}`;
+  }
+}
+
 export default function metadataHandler(request, response) {
   /**
    * @type {ElastalertServer}
    */
-  
   client.search({
     index: config.writeback_index,
     type: request.params.type,
     body: {
       from : request.query.from || 0, 
-      size : request.query.size || 10,
+      size : request.query.size || 100,
       query: {
-        match_all: {}
+        query_string: {
+          query: getQueryString(request)
+        }
       },
       sort: [{ '@timestamp': { order: 'desc' } }]
     }

src/routes/routes.js

@@ -15,6 +15,7 @@ import testPostHandler from '../handlers/test/post';
 import configGetHandler from '../handlers/config/get';
 import configPostHandler from '../handlers/config/post';
 import metadataHandler from '../handlers/metadata/get';
+import mappingHandler from '../handlers/mapping/get';
 
 /**
  * A server route.
@@ -80,6 +81,11 @@ let routes = [
     path: 'metadata/:type',
     method: ['GET'],
     handler: [metadataHandler]
+  },
+  {
+    path: 'mapping/:index',
+    method: ['GET'],
+    handler: [mappingHandler]
   }
 ];