Disable Watcher script optimization for stored scripts

x-pack/plugin/watcher/src/main/java/org/elasticsearch/xpack/watcher/common/text/TextTemplate.java

@@ -29,12 +29,12 @@ public class TextTemplate implements ToXContent {
 
     private final Script script;
     private final String inlineTemplate;
-    private final boolean isUsingMustache;
+    private final boolean mayRequireCompilation;
 
     public TextTemplate(String template) {
         this.script = null;
         this.inlineTemplate = template;
-        this.isUsingMustache = template.contains("{{");
+        this.mayRequireCompilation = template.contains("{{");
     }
 
     public TextTemplate(String template, @Nullable XContentType contentType, ScriptType type,
@@ -50,14 +50,14 @@ public TextTemplate(String template, @Nullable XContentType contentType, ScriptT
             params = new HashMap<>();
         }
         this.script = new Script(type, type == ScriptType.STORED ? null : Script.DEFAULT_TEMPLATE_LANG, template, options, params);
-        this.isUsingMustache = template.contains("{{");
         this.inlineTemplate = null;
+        this.mayRequireCompilation = script.getType() == ScriptType.STORED || script.getIdOrCode().contains("{{");
     }
 
     public TextTemplate(Script script) {
         this.script = script;
         this.inlineTemplate = null;
-        this.isUsingMustache = script.getIdOrCode().contains("{{");
+        this.mayRequireCompilation = script.getType() == ScriptType.STORED || script.getIdOrCode().contains("{{");
     }
 
     public Script getScript() {
@@ -68,8 +68,14 @@ public String getTemplate() {
         return script != null ? script.getIdOrCode() : inlineTemplate;
     }
 
-    public boolean isUsingMustache() {
-        return isUsingMustache;
+    /**
+     * Check if compilation may be required.
+     * If a stored script is used, we cannot tell at this stage, so we always assume
+     * that stored scripts require compilation.
+     * If an inline script is used, we checked for the mustache opening brackets
+     */
+    public boolean mayRequireCompilation() {
+        return mayRequireCompilation;
     }
 
     public XContentType getContentType() {

x-pack/plugin/watcher/src/main/java/org/elasticsearch/xpack/watcher/common/text/TextTemplateEngine.java

@@ -32,7 +32,7 @@ public String render(TextTemplate textTemplate, Map<String, Object> model) {
         String mediaType = compileParams(detectContentType(template));
         template = trimContentType(textTemplate);
 
-        if (textTemplate.isUsingMustache() == false) {
+        if (textTemplate.mayRequireCompilation() == false) {
             return template;
         }
 

x-pack/plugin/watcher/src/main/java/org/elasticsearch/xpack/watcher/notification/email/EmailTemplate.java

@@ -455,7 +455,7 @@ public boolean handle(String fieldName, XContentParser parser) throws IOExceptio
         static void validateEmailAddresses(TextTemplate ... emails) {
             for (TextTemplate emailTemplate : emails) {
                 // no mustache, do validation
-                if (emailTemplate.isUsingMustache() == false) {
+                if (emailTemplate.mayRequireCompilation() == false) {
                     String email = emailTemplate.getTemplate();
                     try {
                         for (Email.Address address : Email.AddressList.parse(email)) {

x-pack/plugin/watcher/src/test/java/org/elasticsearch/xpack/watcher/common/text/TextTemplateTests.java

@@ -225,6 +225,32 @@ public void testParserInvalidMissingText() throws Exception {
         assertEquals("[1:2] [script] unknown field [type]", ex.getMessage());
     }
 
+    public void testMustacheTemplateRequiresCompilation() {
+        final TextTemplate inlineTemplateRequiresCompilation = createTextTemplate(ScriptType.INLINE, "{{foo.bar}}");
+        assertThat(inlineTemplateRequiresCompilation.mayRequireCompilation(), is(true));
+
+        final TextTemplate inlineTemplateNoRequiresCompilation = createTextTemplate(ScriptType.INLINE, "script without mustache");
+        assertThat(inlineTemplateNoRequiresCompilation.mayRequireCompilation(), is(false));
+
+        final TextTemplate storedScriptTemplate = createTextTemplate(ScriptType.STORED, "stored_script_id");
+        assertThat(storedScriptTemplate.mayRequireCompilation(), is(true));
+    }
+
+    private TextTemplate createTextTemplate(ScriptType type, String idOrCode) {
+        final TextTemplate template;
+        if (randomBoolean()) {
+            if (type == ScriptType.STORED) {
+                template = new TextTemplate(new Script(type, null, idOrCode, null, Collections.emptyMap()));
+            } else {
+                template = new TextTemplate(new Script(type, lang, idOrCode, Collections.emptyMap(), Collections.emptyMap()));
+            }
+        } else {
+            template = new TextTemplate(idOrCode, null, type,  null);
+        }
+
+        return template;
+    }
+
     public void testNullObject() throws Exception {
         assertThat(engine.render(null ,new HashMap<>()), is(nullValue()));
     }