Add profile and explain parameters to template API

We can now run templates using `explain` and/or `profile` parameters.
Which is interesting when you have defined a complicated profile but want to debug it in an easier way than running the full query again.

You can use `explain` parameter when running a template:

```js
GET /_search/template
{
  "file": "my_template",
  "params": {
    "status": [ "pending", "published" ]
  },
  "explain": true
}
```

You can use `profile` parameter when running a template:

```js
GET /_search/template
{
  "file": "my_template",
  "params": {
    "status": [ "pending", "published" ]
  },
  "profile": true
}
```

4 files changed, 42 insertions, 0 deletions

diff --git a/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/RestSearchTemplateAction.java b/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/RestSearchTemplateAction.java
index 18637b15e8..6d830a21f5 100644
--- a/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/RestSearchTemplateAction.java
+++ b/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/RestSearchTemplateAction.java
@@ -68,6 +68,8 @@ public class RestSearchTemplateAction extends BaseRestHandler {
             request.setScriptType(ScriptService.ScriptType.STORED);
             request.setScript(s);
         }, new ParseField("id"));
+        PARSER.declareBoolean(SearchTemplateRequest::setExplain, new ParseField("explain"));
+        PARSER.declareBoolean(SearchTemplateRequest::setProfile, new ParseField("profile"));
         PARSER.declareField((parser, request, value) -> {
             request.setScriptType(ScriptService.ScriptType.INLINE);
             if (parser.currentToken() == XContentParser.Token.START_OBJECT) {
diff --git a/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/SearchTemplateRequest.java b/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/SearchTemplateRequest.java
index a4a6533604..1fa7f24de8 100644
--- a/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/SearchTemplateRequest.java
+++ b/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/SearchTemplateRequest.java
@@ -41,6 +41,8 @@ public class SearchTemplateRequest extends ActionRequest<SearchTemplateRequest>
 
     private SearchRequest request;
     private boolean simulate = false;
+    private boolean explain = false;
+    private boolean profile = false;
     private ScriptService.ScriptType scriptType;
     private String script;
     private Map<String, Object> scriptParams;
@@ -69,6 +71,22 @@ public class SearchTemplateRequest extends ActionRequest<SearchTemplateRequest>
         this.simulate = simulate;
     }
 
+    public boolean isExplain() {
+        return explain;
+    }
+
+    public void setExplain(boolean explain) {
+        this.explain = explain;
+    }
+
+    public boolean isProfile() {
+        return profile;
+    }
+
+    public void setProfile(boolean profile) {
+        this.profile = profile;
+    }
+
     public ScriptService.ScriptType getScriptType() {
         return scriptType;
     }
@@ -123,6 +141,8 @@ public class SearchTemplateRequest extends ActionRequest<SearchTemplateRequest>
         super.readFrom(in);
         request = in.readOptionalStreamable(SearchRequest::new);
         simulate = in.readBoolean();
+        explain = in.readBoolean();
+        profile = in.readBoolean();
         scriptType = ScriptService.ScriptType.readFrom(in);
         script = in.readOptionalString();
         if (in.readBoolean()) {
@@ -135,6 +155,8 @@ public class SearchTemplateRequest extends ActionRequest<SearchTemplateRequest>
         super.writeTo(out);
         out.writeOptionalStreamable(request);
         out.writeBoolean(simulate);
+        out.writeBoolean(explain);
+        out.writeBoolean(profile);
         ScriptService.ScriptType.writeTo(scriptType, out);
         out.writeOptionalString(script);
         boolean hasParams = scriptParams != null;
diff --git a/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/SearchTemplateRequestBuilder.java b/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/SearchTemplateRequestBuilder.java
index 811c2523e0..52f51b7254 100644
--- a/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/SearchTemplateRequestBuilder.java
+++ b/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/SearchTemplateRequestBuilder.java
@@ -47,6 +47,22 @@ public class SearchTemplateRequestBuilder
         return this;
     }
 
+    /**
+     * Enables explanation for each hit on how its score was computed. Disabled by default
+     */
+    public SearchTemplateRequestBuilder setExplain(boolean explain) {
+        request.setExplain(explain);
+        return this;
+    }
+
+    /**
+     * Enables profiling of the query. Disabled by default
+     */
+    public SearchTemplateRequestBuilder setProfile(boolean profile) {
+        request.setProfile(profile);
+        return this;
+    }
+
     public SearchTemplateRequestBuilder setScriptType(ScriptService.ScriptType scriptType) {
         request.setScriptType(scriptType);
         return this;
diff --git a/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/TransportSearchTemplateAction.java b/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/TransportSearchTemplateAction.java
index 9df5a29b9c..f323fcf450 100644
--- a/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/TransportSearchTemplateAction.java
+++ b/modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/TransportSearchTemplateAction.java
@@ -84,6 +84,8 @@ public class TransportSearchTemplateAction extends HandledTransportAction<Search
                 SearchSourceBuilder builder = SearchSourceBuilder.searchSource();
                 builder.parseXContent(new QueryParseContext(searchRequestParsers.queryParsers, parser, parseFieldMatcher),
                     searchRequestParsers.aggParsers, searchRequestParsers.suggesters, searchRequestParsers.searchExtParsers);
+                builder.explain(request.isExplain());
+                builder.profile(request.isProfile());
                 searchRequest.source(builder);
 
                 searchAction.execute(searchRequest, new ActionListener<SearchResponse>() {