diff --git a/server/src/main/java/org/elasticsearch/cluster/metadata/IndexTemplateMetaData.java b/server/src/main/java/org/elasticsearch/cluster/metadata/IndexTemplateMetaData.java
index 88bf3a629afd1..36a1ae1aad0fa 100644
--- a/server/src/main/java/org/elasticsearch/cluster/metadata/IndexTemplateMetaData.java
+++ b/server/src/main/java/org/elasticsearch/cluster/metadata/IndexTemplateMetaData.java
@@ -20,6 +20,7 @@
 
 import com.carrotsearch.hppc.cursors.ObjectCursor;
 import com.carrotsearch.hppc.cursors.ObjectObjectCursor;
+import org.apache.logging.log4j.LogManager;
 import org.elasticsearch.ElasticsearchParseException;
 import org.elasticsearch.Version;
 import org.elasticsearch.cluster.AbstractDiffable;
@@ -32,6 +33,7 @@
 import org.elasticsearch.common.compress.CompressedXContent;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
+import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.util.set.Sets;
 import org.elasticsearch.common.xcontent.ToXContent;
@@ -51,6 +53,8 @@
 
 public class IndexTemplateMetaData extends AbstractDiffable<IndexTemplateMetaData> {
 
+    private static final DeprecationLogger deprecationLogger = new DeprecationLogger(LogManager.getLogger(IndexTemplateMetaData.class));
+
     private final String name;
 
     private final int order;
@@ -97,6 +101,11 @@ public IndexTemplateMetaData(String name, int order, Integer version,
         this.patterns = patterns;
         this.settings = settings;
         this.mappings = mappings;
+        if (this.mappings.size() > 1) {
+            deprecationLogger.deprecatedAndMaybeLog("index-templates",
+                "Index template {} contains multiple typed mappings; templates in 8x will only support a single mapping",
+                name);
+        }
         this.aliases = aliases;
     }
 
diff --git a/server/src/test/java/org/elasticsearch/cluster/metadata/IndexTemplateMetaDataTests.java b/server/src/test/java/org/elasticsearch/cluster/metadata/IndexTemplateMetaDataTests.java
index 03d10aca7e812..e535e471d88e9 100644
--- a/server/src/test/java/org/elasticsearch/cluster/metadata/IndexTemplateMetaDataTests.java
+++ b/server/src/test/java/org/elasticsearch/cluster/metadata/IndexTemplateMetaDataTests.java
@@ -32,6 +32,7 @@
 import org.elasticsearch.common.xcontent.json.JsonXContent;
 import org.elasticsearch.test.ESTestCase;
 
+import java.io.IOException;
 import java.util.Arrays;
 import java.util.Collections;
 
@@ -168,4 +169,15 @@ public void testFromToXContent() throws Exception {
             assertThat(parsed, equalTo(template));
         }
     }
+
+    public void testDeprecationWarningsOnMultipleMappings() throws IOException {
+        IndexTemplateMetaData.Builder builder = IndexTemplateMetaData.builder("my-template");
+        builder.patterns(Arrays.asList("a", "b"));
+        builder.putMapping("type1", "{\"type1\":{}}");
+        builder.putMapping("type2", "{\"type2\":{}}");
+        builder.build();
+
+        assertWarnings("Index template my-template contains multiple typed mappings; " +
+            "templates in 8x will only support a single mapping");
+    }
 }