Allow warnings about 'global' template in upgrade tests (#59242)

These tests sometimes install a template so they can be compatible with older versions, but they run
amok of the occasionally installed "global" template which changes the default number of shards.

This commit adds `allowedWarnings` and allows these warnings to be present, but doesn't fail if they
are not (since the global template is only randomly installed).

Resolves #58807
Resolves #58258

qa/rolling-upgrade/src/test/java/org/elasticsearch/upgrades/IndexingIT.java

@@ -96,6 +96,8 @@ public class IndexingIT extends AbstractRollingTestCase {
             Request createTestIndex = new Request("PUT", "/test_index");
             createTestIndex.setJsonEntity("{\"settings\": {\"index.number_of_replicas\": 0}}");
             client().performRequest(createTestIndex);
+            allowedWarnings("index [test_index] matches multiple legacy templates [global, prevent-bwc-deprecation-template], " +
+                "composable templates will only match a single template");
 
             String recoverQuickly = "{\"settings\": {\"index.unassigned.node_left.delayed_timeout\": \"100ms\"}}";
             Request createIndexWithReplicas = new Request("PUT", "/index_with_replicas");

test/framework/src/main/java/org/elasticsearch/test/ESTestCase.java

@@ -75,6 +75,7 @@ import org.elasticsearch.common.transport.TransportAddress;
 import org.elasticsearch.common.util.MockBigArrays;
 import org.elasticsearch.common.util.MockPageCacheRecycler;
 import org.elasticsearch.common.util.concurrent.ThreadContext;
+import org.elasticsearch.common.util.set.Sets;
 import org.elasticsearch.common.xcontent.LoggingDeprecationHandler;
 import org.elasticsearch.common.xcontent.NamedXContentRegistry;
 import org.elasticsearch.common.xcontent.ToXContent;
@@ -430,6 +431,33 @@ public abstract class ESTestCase extends LuceneTestCase {
         assertWarnings(true, expectedWarnings);
     }
 
+    /**
+     * Allow the given warnings, but don't require their presence.
+     */
+    protected final void allowedWarnings(String... allowedWarnings) {
+        if (enableWarningsCheck() == false) {
+            throw new IllegalStateException("unable to check warning headers if the test is not set to do so");
+        }
+        try {
+            final List<String> actualWarnings = threadContext.getResponseHeaders().get("Warning");
+            if (actualWarnings == null) {
+                return;
+            }
+            final Set<String> actualWarningValues =
+                actualWarnings.stream()
+                    .map(s -> DeprecationLogger.extractWarningValueFromWarningHeader(s, true))
+                    .map(DeprecationLogger::escapeAndEncode)
+                    .collect(Collectors.toSet());
+            Set<String> expectedWarnings = new HashSet<>(Arrays.asList(allowedWarnings));
+            final Set<String> warningsNotExpected = Sets.difference(actualWarningValues, expectedWarnings);
+            assertThat("Found " + warningsNotExpected.size() + " unexpected warnings\nExpected: "
+                    + expectedWarnings + "\nActual: " + actualWarningValues,
+                warningsNotExpected.size(), equalTo(0));
+        } finally {
+            resetDeprecationLogger();
+        }
+    }
+
     protected final void assertWarnings(boolean stripXContentPosition, String... expectedWarnings) {
         if (enableWarningsCheck() == false) {
             throw new IllegalStateException("unable to check warning headers if the test is not set to do so");

x-pack/qa/rolling-upgrade/src/test/java/org/elasticsearch/upgrades/IndexingIT.java

@@ -75,6 +75,8 @@ public class IndexingIT extends AbstractUpgradeTestCase {
             Request createTestIndex = new Request("PUT", "/test_index");
             createTestIndex.setJsonEntity("{\"settings\": {\"index.number_of_replicas\": 0}}");
             client().performRequest(createTestIndex);
+            allowedWarnings("index [test_index] matches multiple legacy templates [global, xpack-prevent-bwc-deprecation-template], " +
+                "composable templates will only match a single template");
 
             String recoverQuickly = "{\"settings\": {\"index.unassigned.node_left.delayed_timeout\": \"100ms\"}}";
             Request createIndexWithReplicas = new Request("PUT", "/index_with_replicas");

x-pack/qa/rolling-upgrade/src/test/java/org/elasticsearch/upgrades/TokenBackwardsCompatibilityIT.java

@@ -89,6 +89,8 @@ public class TokenBackwardsCompatibilityIT extends AbstractUpgradeTestCase {
         assertNotNull(refreshToken);
 
         storeTokens(client(), 1, accessToken, refreshToken);
+        allowedWarnings("index [token_backwards_compatibility_it] matches multiple legacy templates " +
+            "[gen-tokens-old-cluster-template, global], composable templates will only match a single template");
 
         responseMap = createTokens(client(), "test_user", "x-pack-test-password");
         accessToken = (String) responseMap.get("access_token");
@@ -175,6 +177,8 @@ public class TokenBackwardsCompatibilityIT extends AbstractUpgradeTestCase {
         assertNotNull(refreshToken);
 
         storeTokens(client(), 5, accessToken, refreshToken);
+        allowedWarnings("index [token_backwards_compatibility_it] matches multiple legacy templates " +
+            "[global, invalid-tokens-old-cluster-template], composable templates will only match a single template");
 
         // invalidate access token
         invalidateAccessToken(client(), accessToken);