From 55e88d6857362031b9e9336e847b38d8dbd0d8d0 Mon Sep 17 00:00:00 2001
From: Alexander Reelsen <alexander@reelsen.net>
Date: Tue, 8 Aug 2017 10:17:58 +0200
Subject: [PATCH] Watcher: Ignore if template is missing when upgrade is
 running (elastic/x-pack-elasticsearch#2199)

If one of the old watcher templates does not exist when we try
to delete it, the upgrade should just continue.

Original commit: elastic/x-pack-elasticsearch@6a52bad329a710b0cef9916154ff380447e57091
---
 .../elasticsearch/xpack/upgrade/Upgrade.java  | 24 +++++++++++++------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/plugin/src/main/java/org/elasticsearch/xpack/upgrade/Upgrade.java b/plugin/src/main/java/org/elasticsearch/xpack/upgrade/Upgrade.java
index 28ef3153cd7..4d7cb9b0743 100644
--- a/plugin/src/main/java/org/elasticsearch/xpack/upgrade/Upgrade.java
+++ b/plugin/src/main/java/org/elasticsearch/xpack/upgrade/Upgrade.java
@@ -29,6 +29,7 @@ import org.elasticsearch.common.settings.SettingsFilter;
 import org.elasticsearch.common.xcontent.NamedXContentRegistry;
 import org.elasticsearch.index.IndexNotFoundException;
 import org.elasticsearch.index.query.QueryBuilders;
+import org.elasticsearch.indices.IndexTemplateMissingException;
 import org.elasticsearch.plugins.ActionPlugin;
 import org.elasticsearch.rest.RestController;
 import org.elasticsearch.rest.RestHandler;
@@ -290,13 +291,22 @@ public class Upgrade implements ActionPlugin {
 
     private static ActionListener<DeleteIndexTemplateResponse> deleteIndexTemplateListener(String name, ActionListener<Boolean> listener,
                                                                                            Runnable runnable) {
-        return ActionListener.wrap(r -> {
-            if (r.isAcknowledged()) {
-                runnable.run();
-            } else {
-                listener.onFailure(new ElasticsearchException("Deleting [{}] template was not acknowledged", name));
-            }
-        }, listener::onFailure);
+        return ActionListener.wrap(
+                r -> {
+                    if (r.isAcknowledged()) {
+                        runnable.run();
+                    } else {
+                        listener.onFailure(new ElasticsearchException("Deleting [{}] template was not acknowledged", name));
+                    }
+                },
+                // if the index template we tried to delete is gone already, no need to worry
+                e -> {
+                    if (e instanceof IndexTemplateMissingException) {
+                        runnable.run();
+                    } else {
+                        listener.onFailure(e);
+                    }
+                });
     }
 
     private static void startWatcherIfNeeded(Boolean shouldStartWatcher, Client client, ActionListener<TransportResponse.Empty> listener) {